Research progress on monitoring vegetation water content by using hyperspectral remote sensing
ZHANG Feng1,2, ZHOU Guang-Sheng,1,2,*1 Chinese Academy of Meteorological Sciences, Beijing 100081, China 2 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
Abstract Aims Vegetation water content is an important biophysical property of terrestrial vegetation, and its remote estimation can be utilized for real-time monitoring of vegetation drought stress. This paper reviewed and summarized the conception and research progress of four commonly used vegetation water indicators: canopy water content, leaf equivalent water thickness, live fuel moisture content, and relative water content. The advantage and disadvantage of various research methods were evaluated by estimating vegetation water content and identifying the limitation in monitoring vegetation water content using optical hyperspectral remote sensing techniques. Finally, the future research tasks were discussed to address issues on accurate monitoring, early warning and evaluation of vegetation drought stress. Keywords：canopy water content;hyperspectral remote sensing;leaf equivalent water thickness;live fuel moisture content;vegetation water status
Fig. 1A diagram showing the relationship of vegetation water content indicators, canopy water content (CWC, g·m-2), leaf equivalent water thickness (EWT, g·cm-2) and live fuel moisture content (LFMC, g·cm-2). DMC, dry matter content (g·cm-2); LAI, leaf area index; mdry, dry mass (g·m-2); mfresh, fresh mass (g·m-2).
AtzbergerC, GuérifM, BaretF, WernerW ( 2010). Comparative analysis of three chemometric techniques for the spectroradiometric assessment of canopy chlorophyll content in winter wheat Computers and Electronics in Agriculture, 73, 165-173. DOIURL [本文引用: 2] Hyperspectral data sets contain useful information for characterizing vegetation canopies not previously available from multi-spectral data sources. However, to make full use of the information content one has to find ways for coping with the strong multi-collinearity in the data. The redundancy directly results from the fact that only a few variables effectively control the vegetation signature. This low dimensionality strongly contrasts with the often more than 100 spectral channels provided by modern spectroradiometers and through imaging spectroscopy. With this study we evaluated three different chemometric techniques specifically designed to deal with redundant (and small) data sets. In addition, a widely used 2-band vegetation index was chosen (NDVI) as a baseline approach. A multi-site and multi-date field campaign was conducted to acquire the necessary reference observations. On small subplots the total canopy chlorophyll content was measured and the corresponding canopy signature (450–2500 nm) was recorded ( n obs = 42). Using this data set we investigated the predictive power and noise sensitivity of stepwise multiple linear regression (SMLR) and two ‘full spectrum’ methods: principal component regression (PCR) and partial least squares regression (PLSR). The NDVI was fitted to the canopy chlorophyll content using an exponential relation. For all techniques, a jackknife approach was used to obtain cross-validated statistics. The PLSR clearly outperformed all other techniques. PLSR gave a cross-validated RMSE of 51 mg m 612 ( R cv 2 = 0.82 ) for canopy chlorophyll contents ranging between 38 and 475 mg m 612 (0.99 ≤ LAI ≤ 8.74 m 2 m 612). The lowest accuracy was achieved using PCR (RMSE cv = 82 mg m 612 and R cv 2 = 0.57). The NDVI, even using chlorophyll optimized band settings, could not reach the accuracy of PLSR. Regarding the sensitivity to artificially created (white) noise, PCR showed some advantages, whereas SMLR was the most sensitive chemometric technique. For relatively small, highly multi-collinear data sets the use of partial least square regression is recommended. PLSR makes full use of the rich spectral information while being relatively insensitive to sensor noise. PLSR provides a regression model where the entire spectral information is taken – in a weighted form – into account. This method seems therefore much better adapted to deal with potentially confounding factors compared to any 2-band vegetation index which can only avoid the most harmful factor of variation.
AtzbergerC, DarvishzadehR, ImmitzerM, SchlerfM, SkidmoreA, Le MaireG ( 2015). Comparative analysis of different retrieval methods for mapping grassland leaf area index using airborne imaging spectroscopy International Journal of Applied Earth Observation and Geoinformation, 43, 19-31. DOIURL [本文引用: 2] Fine scale maps of vegetation biophysical variables are useful status indicators for monitoring and managing national parks and endangered habitats. Here, we assess in a comparative way four different retrieval methods for estimating leaf area index (LAI) in grassland: two radiative transfer model (RTM) inversion methods (one based on look-up-tables (LUT) and one based on predictive equations) and two statistical modelling methods (one partly, the other entirely based on in situ data). For prediction, spectral data were used that had been acquired over Majella National Park in Italy by the airborne hyperspectral HyMap instrument. To assess the performance of the four investigated models, the normalized root mean squared error (nRMSE) and coefficient of determination ( R 2 ) between estimates and in situ LAI measurements are reported ( n 02=0241). Using a jackknife approach, we also quantified the accuracy and robustness of empirical models as a function of the size of the available calibration data set. The results of the study demonstrate that the LUT-based RTM inversion yields higher accuracies for LAI estimation ( R 2 02=020.91, nRMSE02=020.18) as compared to RTM inversions based on predictive equations ( R 2 02=020.79, nRMSE02=020.38). The two statistical methods yield accuracies similar to the LUT method. However, as expected, the accuracy and robustness of the statistical models decrease when the size of the calibration database is reduced to fewer samples. The results of this study are of interest for the remote sensing community developing improved inversion schemes for spaceborne hyperspectral sensors applicable to different vegetation types. The examples provided in this paper may also serve as illustrations for the drawbacks and advantages of physical and empirical models.
BarrsHD, WeatherleyPE ( 1962). A re-examination of the relative turgidity technique for estimating water deficits in leaves Australian Journal of Biological Sciences, 15, 413-428. DOIURL [本文引用: 1] The relative turgidity technique consists in comparing the initial and turgid water contents, on a percentage basis, of disks punched from leaves, the turgid water content being obtained by floating the disks on water.
BowyerP, DansonFM ( 2004). Sensitivity of spectral reflectance to variation in live fuel moisture content at leaf and canopy level Remote Sensing of Environment, 92, 297-308. DOIURL [本文引用: 2] This paper uses a modelling approach to investigate the sensitivity of reflectance data at leaf and canopy level to variation in the biophysical variables that are used to compute FMC. At the leaf level, the results show that the sensitivity of reflectance to variation in leaf water and dry matter content, used to compute FMC, is greatest in the SWIR and NIR, respectively. Variation in FMC has no effect in the visible wavelengths. At the canopy level, the results show that the sensitivity of reflectance to variation in leaf water and dry matter content is heavily dependent upon the type of model used and the range of variation over which the variables are tested. In the longer wavelengths of the SWIR, the competing influence of variable leaf area index, fractional vegetation cover, and solar zenith angle is shown to be greater than that at the shorter wavelengths of the SWIR and NIR. Empirical relationships between the normalised difference water index (NDWI) and FMC are shown to be weaker than that with canopy water content. However, when the range of the variables under study is more limited, useful empirical relationships between FMC and remotely sensed VI may be established.
BurganRE ( 1996). Use of remotely sensed data for fire danger estimation EARSeL Advances in Remote Sensing, 4(4), 1-8. URL [本文引用: 2] react-text: 511 Many migrating herbivores rely on plant biomass to fuel their life cycles and have adapted to following changes in plant quality through time. The green wave hypothesis predicts that herbivorous waterfowl will follow the wave of food availability and quality during their spring migration. However, testing this hypothesis is hampered by the large geographical range these birds cover. The... /react-text react-text: 512 /react-text [Show full abstract]
CaoZ, WangQ, ZhengC ( 2015). Best hyperspectral indices for tracing leaf water status as determined from leaf dehydration experiments Ecological Indicators, 54, 96-107. DOIURL [本文引用: 1] Leaf water status information is highly needed for monitoring plant physiological processes and assessing drought stress. Retrieval of leaf water status based on hyperspectral indices has been shown to be easy and rapid. However, a universal index that is applicable to various plants remains a considerable challenge, primarily due to the limited range of field-measured datasets. In this study, a leaf dehydration experiment was designed to obtain a relatively comprehensive dataset with ranges that are difficult to obtain in field measurements. The relative water content (RWC) and equivalent water thickness (EWT) were chosen as the surrogates of leaf water status. Moreover, five common types of hyperspectral indices including: single reflectance (R), wavelength difference (D), simple ratio (SR), normalized ratio (ND) and double difference (DDn) were applied to determine the best indices. The results indicate that values of original reflectance, reflectance difference and reflectance sensitivity increased significantly, particularly within the 350 700nm and 1300 2500nm domains, with a decrease in leaf water. The identified best indices for RWC and EWT, when all the species were considered together, were the first derivative reflectance based ND type index of dND (1415, 1530) and SR type index of dSR (1530, 1895), with R2 values of 0.95 (p<0.001) and 0.97 (p<0.001), respectively, better than previously published indices. Even so, different best indices for different species were identified, most probably due to the differences in leaf anatomy and physiological processes during leaf dehydration. Although more plant species and field-measured datasets are still needed in future studies, the recommend indices based on derivative spectra provide a means to monitor drought-induced plant mortality in temperate climate regions.
CarlsonTN, CapehartWJ, GilliesRR ( 1995). A new look at the simplified method for remote sensing of daily evapotranspiration Remote Sensing of Environment, 54, 161-167. DOIURL [本文引用: 1] A modification of the so-called “Simplified Method” used to obtain the integrated daily evapotranspiration from surface radiant temperature over variable vegetation cover is proposed. Mathematically, the simplified equation takes the form Rn 24 61 LE 24 =(T o13 61 T a13 ) n , where Rn 24 and LE 24 are, respectively, the integrated net radiation and evapotranspiration over a 24-h period and T 013 and T a13 are, respectively, the surface radiant and the 50-m air temperatures at 1300 local time. B and n are pseudo constants given as functions of the normalized difference vegetation index (NDVI), expressed as a scaled index N * . Both N * and T a 13 are obtained with the aid of remotely determined measurements, which are viewed on scatterplots of T 013 versus NDVI.
CeccatoP, GobronN, FlasseS, PintyB, TarantolaS ( 2002). Designing a spectral index to estimate vegetation water content from remote sensing data: Part 1: Theoretical approach Remote Sensing of Environment, 82, 188-197. DOIURL [本文引用: 2] This paper describes the methodology used to create a spectral index to retrieve vegetation water content from remotely sensed data in the solar spectrum domain. A global sensitivity analysis (GSA) using radiative transfer models is used to understand and quantify vegetation water content effects on the signal measured at three levels: leaf, canopy, and atmosphere. An index is then created that optimises retrieval of vegetation water content (in terms of water quantity per unit area at canopy level) and minimises perturbing effects of geophysical and atmospheric effects. The new index, optimised for the new SPOT-VEGETATION sensor, is presented as an example. Limitations and robustness of the index are also discussed.
ChoMA, SkidmoreA, CorsiF, WierenSE, SobhanI ( 2007). Estimation of green grass/herb biomass from airborne hyperspectral imagery using spectral indices and partial least squares regression International Journal of Applied Earth Observation and Geoinformation, 9, 414-424. DOIURL [本文引用: 1] The main objective was to determine whether partial least squares (PLS) regression improves grass/herb biomass estimation when compared with hyperspectral indices, that is normalised difference vegetation index (NDVI) and red-edge position (REP). To achieve this objective, fresh green grass/herb biomass and airborne images (HyMap) were collected in the Majella National Park, Italy in the summer of 2005. The predictive performances of hyperspectral indices and PLS regression models were then determined and compared using calibration ( n = 30) and test ( n = 12) data sets. The regression model derived from NDVI computed from bands at 740 and 771 nm produced a lower standard error of prediction (SEP = 264 g m 612) on the test data compared with the standard NDVI involving bands at 665 and 801 nm (SEP = 331 g m 612), but comparable results with REPs determined by various methods (SEP = 261 to 295 g m 612). PLS regression models based on original, derivative and continuum-removed spectra produced lower prediction errors (SEP = 149 to 256 g m 612) compared with NDVI and REP models. The lowest prediction error (SEP = 149 g m 612, 19% of mean) was obtained with PLS regression involving continuum-removed bands. In conclusion, PLS regression based on airborne hyperspectral imagery provides a better alternative to univariate regression involving hyperspectral indices for grass/herb biomass estimation in the Majella National Park.
ChuviecoE, RianõD, AguadoI, CoceroD ( 2002). Estimation of fuel moisture content from multi temporal analysis of Landsat Thematic Mapper reflectance data: Applications in fire danger assessment International Journal of Remote Sensing, 23, 2145-2162. DOIURL [本文引用: 1] The objective of this paper was to define indices based on reflectance measurements performed by the Landsat Thematic Mapper (TM) sensor for estimating water content of live Mediterranean fuels for fire danger estimation. Seven Landsat TM images were processed and correlated with fuel moisture content (FMC) of several live species of Mediterranean grassland and shrubland. Raw bands were converted to reflectances, and several indices potentially related to water content were calculated from them. Pearson r correlation coefficients and linear regression analysis were computed in order to estimate FMC. Those indices based on the short wave infrared bands (SWIR: 1.4-2.5 w m) and on the contrast between this band and the near-infrared band offered the best estimations. For grassland, the integral of visible and SWIR bands provided the highest correlation, but also raw reflectances and Normalized Difference Vegetation Indices (NDVIs) provide significant r values ( r 2 above 0.8). For shrub species, indices that include SWIR reflectances performed much better than NDVI, because the SWIR band is more sensitive to water absorption, whereas NDVI estimates FMC indirectly, only from the effects of chlorophyll changes due to water variation content and leaf area index. The most significant relations were found with the derivatives of bands 4-5 and 2-3, and again the integral of visible and SWIR bands. Multiple regression analysis provided adjusted r 2 values of 0.84 for grasslands and 0.74 for shrublands. Average errors of 23.45-40% in the estimation of FMC for grasslands were found, depending on which variables were included in the multiple regression. For the FMC estimation of shrub species, errors were lower (from 7.94 to 19.40%), since the range of FMC values was also lower.
CleversJGPW, KooistraL, SchaepmanME ( 2008). Using spectral information from the NIR water absorption features for the retrieval of canopy water content International Journal of Applied Earth Observation and Geoinformation, 10, 388-397. DOIURL [本文引用: 5] Canopy water content (CWC) is important for mapping and monitoring the condition of the terrestrial ecosystem. Spectral information related to the water absorption features at 970 nm and 1200 nm offers possibilities for deriving information on CWC. In this study, we compare the use of derivative spectra, spectral indices and continuum removal techniques for these regions. Hyperspectral reflectance data representing a range of canopies were simulated using the combined PROSPECT + SAILH model. Best results in estimating CWC were obtained by using spectral derivatives at the slopes of the 970 nm and 1200 nm water absorption features. Real data from two different test sites were analysed. Spectral information at both test sites was obtained with an ASD FieldSpec spectrometer, whereas at the second site HyMap airborne imaging spectrometer data were also acquired. Best results were obtained for the derivative spectra. In order to avoid the potential influence of atmospheric water vapour absorption bands the derivative of the reflectance on the right slope of the canopy water absorption feature at 970 nm can best be used for estimating CWC.
CleversJGPW, KooistraL, SchaepmanME ( 2010). Estimating canopy water content using hyperspectral remote sensing data International Journal of Applied Earth Observation and Geoinformation, 12, 119-125. DOIURL [本文引用: 3] PROSAIL simulations (using coupled SAIL/PROSPECT-5 models) showed a linear relationship between the first derivative over the 1015–105002nm spectral interval and CWC ( R 2 02=020.97). For 8 plots at the floodplain site the spectral derivative over the 1015–105002nm interval obtained with an ASD FieldSpec spectroradiometer yielded an R 2 of 0.51 with CWC. For 40 plots at the fen meadow ASD FieldSpec spectral measurements yielded an R 2 of 0.68 for the derivative over the 1015–105002nm interval with CWC. Consistency of the results confirmed the potential of using simulation results for calibrating the relationship between this first derivative and CWC.
CohenW, MaierspergerT, GowerS, TurnerD ( 2003). An improved strategy for regression of biophysical variables and Landsat ETM+ data Remote Sensing of Environment, 84, 561-571. DOIURL [本文引用: 1] Empirical models are important tools for relating field-measured biophysical variables to remote sensing data. Regression analysis has been a popular empirical method of linking these two types of data to provide continuous estimates for variables such as biomass, percent woody canopy cover, and leaf area index (LAI). Traditional methods of regression are not sufficient when resulting biophysical surfaces derived from remote sensing are subsequently used to drive ecosystem process models. Most regression analyses in remote sensing rely on a single spectral vegetation index (SVI) based on red and near-infrared reflectance from a single date of imagery. There are compelling reasons for utilizing greater spectral dimensionality, and for including SVIs from multiple dates in a regression analysis. Moreover, when including multiple SVIs and/or dates, it is useful to integrate these into a single index for regression modeling. Selection of an appropriate regression model, use of multiple SVIs from multiple dates of imagery as predictor variables, and employment of canonical correlation analysis (CCA) to integrate these multiple indices into a single index represent a significant strategic improvement over existing uses of regression analysis in remote sensing. To demonstrate this improved strategy, we compared three different types of regression models to predict LAI for an agro-ecosystem and live tree canopy cover for a needleleaf evergreen boreal forest: traditional ( Y on X) ordinary least squares (OLS) regression, inverse ( X on Y) OLS regression, and an orthogonal regression method called reduced major axis (RMA). Each model incorporated multiple SVIs from multiple dates and CCA was used to integrate these. For a given dataset, the three regression-modeling approaches produced identical coefficients of determination and intercepts, but different slopes, giving rise to divergent predictive characteristics. The traditional approach yielded the lowest root mean square error (RMSE), but the variance in the predictions was lower than the variance in the observed dataset. The inverse method had the highest RMSE and the variance was inflated relative to the variance of the observed dataset. RMA provided an intermediate set of predictions in terms of the RMSE, and the variance in the observations was preserved in the predictions. These results are predictable from regression theory, but that theory has been essentially ignored within the discipline of remote sensing.
ColomboR, MeroniM, MarchesiA, BusettoL, RossiniM, GiardinoC, PanigadaC ( 2008). Estimation of leaf and canopy water content in poplar plantations by means of hyperspectral indices and inverse modeling Remote Sensing of Environment, 112, 1820-1834. DOIURL [本文引用: 2] This study investigates the applicability of empirical and radiative transfer models to estimate water content at leaf and landscape level. The main goal is to evaluate and compare the accuracy of these two approaches for estimating leaf water content by means of laboratory reflectance/transmittance measurements and for mapping leaf and canopy water content by using airborne Multispectral Infrared and Visible Imaging Spectrometer (MIVIS) data acquired over intensive poplar plantations (Ticino, Italy). At leaf level, we tested the performance of different spectral indices to estimate leaf equivalent water thickness (EWT) and leaf gravimetric water content (GWC) by using inverse ordinary least squares (OLS) regression, and reduced major axis (RMA) regression. The analysis showed that leaf reflectance is related to changes in EWT rather than GWC, with best results obtained by using RMA regression by exploiting the spectral index related to the continuum removed area of the 1200 nm water absorption feature with an explained variance of 61% and prediction error of 6.6%. Moreover, we inverted the PROSPECT leaf radiative transfer model to estimate leaf EWT and GWC and compared the results with those obtained by means of empirical models. The inversion of this model showed that leaf EWT can be successfully estimated with no prior information with mean relative errors of 14% and determination coefficient of 0.65. Inversion of the PROSPECT model showed some difficulties in the simultaneous estimation of leaf EWT and dry matter content, which led to large errors in GWC estimation. At landscape level with MIVIS data, we tested the performance of different spectral indices to estimate canopy water per unit ground area (EWT canopy). We found a relative error of 20% using a continuum removed spectral index around 1200 nm. Furthermore, we used a model simulation to evaluate the possibility of applying empirical models based on appositely developed MIVIS double ratios to estimate mean leaf EWT at landscape level ( EWT ). It is shown that combined indices (double ratios) yielded significant results in estimating leaf EWT at landscape level by using MIVIS data (with errors around 2.6%), indicating their potential in reducing the effects of LAI on the recorded signal. The accuracy of the empirical estimation of EWT canopy and EWT was finally compared with that obtained from inversion of the PROSPECT + SAILH canopy reflectance model to evaluate the potential of both methods for practical applications. A relative error of 27% was found for EWT canopy and an overestimation of leaf EWT with relative errors around 19%. Results arising from this remote sensing application support the robustness of hyperspectral regression indices for estimating water content at both leaf and landscape level, with lower relative errors compared to those obtained from inversion of leaf and 1D canopy radiative transfer models.
CurranP ( 1989). Remote sensing of foliar chemistry Remote Sensing of Environment, 30, 271-278. DOIURL [本文引用: 1] Remotely sensed data are being used to estimate foliar chemical content as a result of our need for the information and our increasing ability to understand and measure foliar spectra. This paper reviews how stepwise multiple regression and deconvolution have been used to extract chemical information from foliar spectra, and concludes that both methods are useful, but neither is ideal. It is recommended that the focus of research be modeling in the long term and experimentation in the short term. Long-term research should increase our understanding of the interaction between radiation and foliar chemistry so that the focus of research can move from leaf model to canopy model to field experiment. Short-term research should aim to design experiments in which remotely sensed data are used to generate unambiguous and accurate estimates of foliar chemical content.
CurranP, DunganJ, PetersonD ( 2001). Estimating the foliar biochemical concentration of leaves with reflectance spectrometry: Testing the Kokaly and Clark methodologies Remote Sensing of Environment, 76, 349-359. DOIURL [本文引用: 1]
DansonFM, StevenMD, MalthusTJ, ClarkJA ( 1992). High spectral resolution data for determining leaf water content International Journal of Remote Sensing, 13, 461-470. DOIURL [本文引用: 6] Laboratory measurements of the spectral reflectance of leaves from a variety of species were made over the 400-2500 nm range using a spectroradiomctcr. The relation between spectral reflectance and leaf water content was investigated and the effect of differences in leaf structure were found to be important. The first derivative of the reflectance spectrum, at wavelengths corresponding to the slopes on the edges of the water absorption bands, was found to be highly correlated with leaf water content and insensitive to differences in leaf structure.
de JongSM, AddinkEA, HoogenboomP, NijlandW ( 2012). The spectral response of Buxus sempervirens to different types of environmental stres—A laboratory experiment ISPRS Journal of Photogrammetry & Remote Sensing, 74, 56-65. [本文引用: 2]
de JongSM, AddinkEA, DoelmanJC ( 2014). Detecting leaf- water content in Mediterranean trees using high-resolution spectrometry International Journal of Applied Earth Observation and Geoinformation, 27, 128-136. DOIURL [本文引用: 1] Water content of the vegetation canopy or individual leaves is an important variable in physiological plant processes. In Mediterranean regions where water availability is an important production limiting factor, it is a strong indicator of vegetation stress. Spectroscopic earth-observation techniques in the solar part of the electromagnetic spectrum provide opportunities to determine leaf and canopy-water content due to the presence of water-absorption bands around 970 and 1200nm. We investigated the possibilities to predict leaf-water content of three dominant tree species in a study area in Mediterranean France using spectral indices. During a field campaign leaf-water content (EWT) was determined and high-resolution spectra were measured of the same leaves. The spectra were measured in two ways: using an optical cable with a field of view of 25 and using a leaf clip with its own artificial illumination source. The spectra were analyzed and related to leaf-water content as original reflectance spectra and as continuum-removed spectra using eight spectral leaf-water indices. Next, reflectance spectra were simulated to explore their sensitivity to environmental conditions like leaf area index and illumination angle using a radiative transfer model. Results show that a good correlation (0.70) exists between leaf-water content and spectral indices using the right slope of the 970nm water-absorption band. Continuum-removal correction of the spectra improved the relations. The model sensitivity analysis illustrated that from a set of five environmental variables leaf area index has, as may be expected, an important impact on leaf-water estimates. This field and model study illustrates that it is feasible to determine foliar water content on the basis of spectral indices located around the minor water-absorption bands with a limited effect of environmental conditions.
DarvishzadehR, SkidmoreA, AtzbergerC, WierenSV ( 2008 a). Estimation of vegetation LAI from hyperspectral reflectance data: Effects of soil type and plant architecture International Journal of Applied Earth Observation and Geoinformation, 10, 358-373. DOIURL [本文引用: 1] The retrieval of canopy biophysical variables is known to be affected by confounding factors such as plant type and background reflectance. The effects of soil type and plant architecture on the retrieval of vegetation leaf area index (LAI) from hyperspectral data were assessed in this study. In situ measurements of LAI were related to reflectances in the red and near-infrared and also to five widely used spectral vegetation indices (VIs). The study confirmed that the spectral contrast between leaves and soil background determines the strength of the LAI–reflectance relationship. It was shown that within a given vegetation species, the optimum spectral regions for LAI estimation were similar across the investigated VIs, indicating that the various VIs are basically summarizing the same spectral information for a given vegetation species. Cross-validated results revealed that, narrow-band PVI was less influenced by soil background effects (0.15 ≤ RMSE cv ≤ 0.56). The results suggest that, when using remote sensing VIs for LAI estimation, not only is the choice of VI of importance but also prior knowledge of plant architecture and soil background. Hence, some kind of landscape stratification is required before using hyperspectral imagery for large-scale mapping of vegetation biophysical variables.
DarvishzadehR, SkidmoreA, SchlerfM, AtzbergerC, CorsiF, ChoM ( 2008 b). LAI and chlorophyll estimation for a heterogeneous grassland using hyperspectral measurements ISPRS Journal of Photogrammetry & Remote Sensing, 63, 409-426. DOIURL [本文引用: 2] The study shows that leaf area index (LAI), leaf chlorophyll content (LCC) and canopy chlorophyll content (CCC) can be mapped in a heterogeneous Mediterranean grassland from canopy spectral reflectance measurements. Canopy spectral measurements were made in the field using a GER 3700 spectroradiometer, along with concomitant values ranged from 0.49 to 0.69). Compared with narrow band indices and red edge inflection point, stepwise multiple linear regression generally improved the estimation of LAI. The estimations were further improved when partial least squares regression was used. When a subset of wavelengths was analyzed, it was found that partial least squares regression had reduced the error in the retrieved parameters. The results of the study highlight the significance of multivariate techniques, such as partial least squares regression, rather than univariate methods such as vegetation indices in estimating heterogeneous grass canopy characteristics.
DarvishzadehR, AtzbergerC, SkidmoreA, SchlerfM ( 2011). Mapping grassland leaf area index with airborne hyperspectral imagery: A comparison study of statistical approaches and inversion of radiative transfer models ISPRS Journal of Photogrammetry & Remote Sensing, 66, 894-906. DOIURL [本文引用: 2] Statistical and physical models have seldom been compared in studying grasslands. In this paper, both modeling approaches are investigated for mapping leaf area index (LAI) in a Mediterranean grassland (Majella National Park, Italy) using HyMap airborne hyperspectral images. We compared inversion of the PROSAIL radiative transfer model with narrow band vegetation indices (NDVI-like and SAVI2-like) and partial least squares regression (PLS). To assess the performance of the investigated models, the normalized RMSE (nRMSE) and R 2 between in situ measurements of leaf area index and estimated parameter values are reported. The results of the study demonstrate that LAI can be estimated through PROSAIL inversion with accuracies comparable to those of statistical approaches ( R 2 02=020.89, nRMSE02=020.22). The accuracy of the radiative transfer model inversion was further increased by using only a spectral subset of the data ( R 2 02=020.91, nRMSE02=020.18). For the feature selection wavebands not well simulated by PROSAIL were sequentially discarded until all bands fulfilled the imposed accuracy requirements.
DengB, YangWN, MuN, ZhangC ( 2016). The research of vegetation water content based on spectrum analysis and angle slope index Spectroscopy and Spectral Analysis, 36, 2546-2552. DOIURL [本文引用: 1] 植被含水量是植被生长状态的重要指示因子,是农业、生态和水文等研究中的重要参数,其诊断对于监测自然植被群落的干旱状况、预报森林火灾等都具有重要意义。通过对植被光谱反射率与植被含水量的相关性分析,发现植被波谱不同波段的光谱反射率与植被含水量的相关性差异很大,其中可见光红光波段（620～700 nm）、近红外波段（800～1 350,1 600～1 950,2 200～2 400 nm）的光谱反射率与植被含水量具有较好的相关性,选取了660,850,1 630和2 200 nm的光谱反射率作为RED,NIR,SWIR1和SWIR2的波段值来建立角度斜率指数;分析了植被含水量与角度斜率指数的关系,将角度斜率指数（SANI,SASI,ANIR）作为反演植被含水量的参量,建立植被含水量与角度斜率指数之间线性回归模型。通过对近红外角度指数ANIR改进,提出了近红外角度归一化指数NANI（near infrared angle normalized index）与近红外角度斜率指数NASI（near infrared angle slope index）,建立植被含水量与NANI和NASI之间线性回归模型,结果显示：NANI与Palacios-Orueta等提出的角度斜率指数（SANI,SASI,ANIR）相比有一定的优势,模型可决系数R^2从原最高0.791提高到0.853,RMSE也从原最小0.047降低到0.039。确定了NANI为反演植被含水量的最佳角度斜率指数,并建立了植被含水量反演模型。该研究主要创新点：在前人研究成果基础上,通过对原角度斜率指数的改进,提出了NANI和NASI角度斜率指数,使其在植被含水量反演上具有更高的精度。 [ 邓兵, 杨武年, 慕楠, 张超 ( 2016). 基于光谱分析与角度斜率指数的植被含水量研究 光谱学与光谱分析, 36, 2546-2552.] DOIURL [本文引用: 1] 植被含水量是植被生长状态的重要指示因子,是农业、生态和水文等研究中的重要参数,其诊断对于监测自然植被群落的干旱状况、预报森林火灾等都具有重要意义。通过对植被光谱反射率与植被含水量的相关性分析,发现植被波谱不同波段的光谱反射率与植被含水量的相关性差异很大,其中可见光红光波段（620～700 nm）、近红外波段（800～1 350,1 600～1 950,2 200～2 400 nm）的光谱反射率与植被含水量具有较好的相关性,选取了660,850,1 630和2 200 nm的光谱反射率作为RED,NIR,SWIR1和SWIR2的波段值来建立角度斜率指数;分析了植被含水量与角度斜率指数的关系,将角度斜率指数（SANI,SASI,ANIR）作为反演植被含水量的参量,建立植被含水量与角度斜率指数之间线性回归模型。通过对近红外角度指数ANIR改进,提出了近红外角度归一化指数NANI（near infrared angle normalized index）与近红外角度斜率指数NASI（near infrared angle slope index）,建立植被含水量与NANI和NASI之间线性回归模型,结果显示：NANI与Palacios-Orueta等提出的角度斜率指数（SANI,SASI,ANIR）相比有一定的优势,模型可决系数R^2从原最高0.791提高到0.853,RMSE也从原最小0.047降低到0.039。确定了NANI为反演植被含水量的最佳角度斜率指数,并建立了植被含水量反演模型。该研究主要创新点：在前人研究成果基础上,通过对原角度斜率指数的改进,提出了NANI和NASI角度斜率指数,使其在植被含水量反演上具有更高的精度。
DzikitiS, VerreynneJS, StuckensJ, StreverA, VerstraetenWW, SwennenR, CoppinP ( 2010). Determining the water status of Satsuma mandarin trees (Citrus unshiu Marcovitch) using spectral indices and by combining hyperspectral and physiological data. Agricultural and Forest Meteorology, 150, 369-379. DOIURL [本文引用: 3] This study investigated the water relations of Satsuma mandarin trees [ Citrus Unshiu Marcovitch] and drought stress indicators used for irrigation scheduling in orchards namely: (1) the midday leaf water potential (MLWP), (2) midday stem (or xylem) water potential (MSWP), (3) predawn leaf water potential and (4) the leaf water content. Remote sensing spectral indices were applied to predict these indicators for trees subjected to different drought stress regimes. Continuous measurements of the MLWP and the MSWP on individual trees during cloudless days showed large fluctuations in the MLWP of up to 2.0 MPa and less variation in the MSWP of 0.30 MPa. The large variability in the MLWP was directly related to stomatal oscillations characteristic of most citrus species and the MSWP measurements were more representative of the tree water status. Spectral indices derived from canopy reflectance data of mature citrus trees in the orchard showed poor correlations with both the MSWP and MLWP. However, using spectral indices from the leaf reflectance of young potted citrus trees showed that the water index (WI) and a narrow-band spectral ratio of the reflectance at 960 and 950 nm wavelengths gave the best predictions of the MSWP with R 2 = 0.77 and 0.79, respectively but only for severely stressed trees. All the indices failed to predict the water potentials of trees with mild or no drought stress ( R 2 < 0.20), although the leaf water content predictions were accurate for both stressed and non-severely stressed trees. Integrating the hyperspectral estimates of leaf water content with the transpiration and soil water potential data in a simple dynamic tree-level water balance model yielded more accurate estimates of the MSWP of non-severely stressed trees. This suggests that in the absence of robust spectral indices for predicting plant water status, as is the case at present, combining hyperspectral remote sensing and in situ data in physiological models potentially yields useful information for irrigation management in orchards.
GaoBC ( 1996). NDWI—A normalized difference water index for remote sensing of vegetation liquid water from space Remote Sensing of Environment, 58, 257-266. DOIURL [本文引用: 1] The normalized difference vegetation index (NDVI), which is equal to (NIR- RED)/(NIR+RED), has been widely used for remote sensing of vegetation for many years. One weakness of this index is that the reflectance of RED channel has no sensitivity to changes in lead area index changes when the leaf area index is equal to 1 or greater due to strong chlorophyll absorption near 0.67 micron. In this paper, another index, namely the normalized difference water index (NDWI), is proposed for remote sensing of vegetation liquid water from space. NDWI is equal to [R(0.86 micrometers ) - R(1.24 micrometers )]/[R(0.86 micrometers ) + R(1.24 micrometers )], where R represents the apparent reflectance. At 0.86 micrometers and 1.24 micrometers , vegetation canopies have similar scattering properties, but slightly different liquid water absorption. The scattering by vegetation canopies enhances the weak liquid water absorption at 1.24 micrometers . As a result, NDWI is sensitive to changes in liquid water content of vegetation canopies. Spectral imaging data acquired with Airborne Visible Infrared Imaging Spectrometer (AVIRIS) over Jasper Ridge, California and Holland, Maine are used to demostrate the usefulness of NDWI. Comparisons between NDWI and NDVI images are also given. Because aerosol scattering effects in the 0.86-1.24 micrometers region are weak, NDWI is less sensitive to atmospheric effects that NDVI.
GilliesRR, CarlsonTN ( 1995). Thermal remote sensing of surface soil water content with partial vegetation cover for incorporation into climate models Journal of Applied Meteorology, 34, 745-756. DOIURL [本文引用: 1] This study outlines a method for the estimation of regional patterns of surface moisture availability (M) and fractional vegetation (Fr) in the presence of spatially variable vegetation cover. The method requires relating variations in satellite-derived (NOAA, Advanced Very High Resolution Radiometer) surface radiant temperature to a vegetation index (computed from satellite visible and near-infrared data) while coupling this association to an inverse modeling scheme. More than merely furnishing surface soil moisture values, the method constitutes a new conceptual and practical approach for combining thermal infrared and vegetation index measurements for incorporating the derived values of Minto hydrologic and atmospheric prediction models.Application of the technique is demonstrated for a region in and around the city of Newcastle upon Tyne situated in the northeast of England. A regional estimate of Mis derived and is probably good for fractional vegetation cover up to 80% before errors in the estimated soil water content become unacceptably large. Moreover, a normalization scheme is suggested from which a nomogram, `universal triangle,' is constructed and is seen to fit the observed data well. The universal triangle also simplifies the inclusion of remotely derived Min hydrology and meteorological models and is perhaps a practicable step toward integrating derived data from satellite measurements in weather forecasting.
GilliesRR, CarlsonTN ( 1997). A verification of the ‘triangle’ method for obtaining surface soil water content and energy fluxes from remote measurements of the normalized difference vegetation index (NDVI) and surface radiant temperature International Journal of Remote Sensing, 18, 3145-3166. DOIURL [本文引用: 1]
GowardSN, HopeAS ( 1989). Evaporation from combined reflected solar and emitted terrestrial radiation: Preliminary FIFE results from AVHRR data Advances in Space Research, 9, 239-249. DOIURL [本文引用: 1] Analysis of the relation between remotely sensed spectral vegetation indices and thermal infrared measurements suggests that presence of vegetation foliage is a primary determinant of observed surface temperature patterns. The form of this relation may be diagnostic of energy balance Bowen ratios and therefore provide an improved means to evaluate land surface evapotranspiration. Observations from the First International Satellite Land Surface Climatology Project Field Experiment conducted in northeastern Kansas, United States in 1987 provide data needed to evaluate this phenomena. Preliminary analysis of NOAA-9 advanced very high resolution radiometer data shows that a strong relation between the spectral vegetation indices and surface temperature is consistently observed. This relation appears to co-vary with surface moisture conditions as expected. However, cloud contamination and view angle effects in the AVHRR data also cause variations in the relation. The potential of combined spectral vegetation indices and surface temperature remotely sensed measurements in surface energy balance analysis appear great. However, the full resources of the of the FIFE experiment will be required to address the cloud cover and view angle effects.
GhulamA, LiZL, QinQM, TongQX, WangJH, KasimuA, ZhuL ( 2007). A method for canopy water content estimation for highly vegetated surfaces-shortwave infrared perpendicular water stress index Science in China Series D: Earth Sciences, 37, 957-965. DOIURL [本文引用: 1] 利用叶片辐射传输模型PROSPECT、植被冠层辐射传输模型SailH和地气辐射传输模型6S,进一步探索近红外、短波红外反射光谱特征,从光谱特征空间的角度,分析地物在NIR-SWIR空间的分异规律,建立监测植被冠层水分含量的新方法-短波红外垂直失水指数(SPSI).通过实地观测数据和叶片、冠层辐射传输模型验证本文提出的新方法,结果表明SPSI和实地观测的植被冠层水分含量(FMC)具有较高的相关性,R2和RMSE分别为0.79,26.41%,证明了SPSI在FMC反演方面有一定的应用潜力. [ 阿布都瓦斯提•吾拉木, 李召良, 秦其明, 童庆禧, 王纪华, 阿里木江•卡斯木, 朱琳 ( 2007). 全覆盖植被冠层水分遥感监测的一种方法: 短波红外垂直失水指数 中国科学D辑: 地球科学, 37, 957-965.] DOIURL [本文引用: 1] 利用叶片辐射传输模型PROSPECT、植被冠层辐射传输模型SailH和地气辐射传输模型6S,进一步探索近红外、短波红外反射光谱特征,从光谱特征空间的角度,分析地物在NIR-SWIR空间的分异规律,建立监测植被冠层水分含量的新方法-短波红外垂直失水指数(SPSI).通过实地观测数据和叶片、冠层辐射传输模型验证本文提出的新方法,结果表明SPSI和实地观测的植被冠层水分含量(FMC)具有较高的相关性,R2和RMSE分别为0.79,26.41%,证明了SPSI在FMC反演方面有一定的应用潜力.
HanLJ, WangPX, WangJD, LiuSM ( 2005). Study on vegetation indices-surface temperature characteristic space Science in China Series D: Earth Sciences, 35, 371-377. DOIURL [本文引用: 2] 植被指数和地表温度是描述陆表过程的重要参数,综合通过遥感手段得到的植被指数和地表温度信息,来分析地表的各种植被覆盖、水分含量等变化过程,有助于更好地认知和评价陆表变化过程,是目前遥感和陆表过程研究中比较前沿的一个方向.文中试图解释清楚归一化植被指数(NDVI)和地表温度(Ts)的各种存在关系及其相互转换过程,尤其是根据NDVI和LAI、地表蒸散的关系,利用LAI-Ts构成的三角形特征空间,解释NDVI达到饱和以后的情况,以便更有效地进行应用. [ 韩丽娟, 王鹏新, 王锦地, 刘绍民 ( 2005). 植被指数-地表温度构成的特征空间研究 中国科学D辑: 地球科学, 35, 371-377.] DOIURL [本文引用: 2] 植被指数和地表温度是描述陆表过程的重要参数,综合通过遥感手段得到的植被指数和地表温度信息,来分析地表的各种植被覆盖、水分含量等变化过程,有助于更好地认知和评价陆表变化过程,是目前遥感和陆表过程研究中比较前沿的一个方向.文中试图解释清楚归一化植被指数(NDVI)和地表温度(Ts)的各种存在关系及其相互转换过程,尤其是根据NDVI和LAI、地表蒸散的关系,利用LAI-Ts构成的三角形特征空间,解释NDVI达到饱和以后的情况,以便更有效地进行应用.
Hunt JrER, RockBN, NobelPS ( 1987). Measurement of leaf relative water content by infrared reflectance Remote Sensing of Environment, 22, 429-435. DOIURL [本文引用: 2] From basic considerations and Beer's law, a leaf water content index incorporating reflectances of wavelengths from 0.76 to 0.90 m and from 1.55 to 1.75 m (Landsat Thematic Mapper Bands TM4 and TM5, respectively) was developed that relates leaf reflectance to leaf relative water content. For the leaf succulent, Agave deserti, the leaf water content index was not significantly different from the relative water content for either individual leaves or an entire plant. Also, the relative water contents of intact plants of Encelia farinosa and Hilaria rigida in the field were estimated by the leaf water content index; variations in the proportion of living to dead leaf area could cause large errors in the estimate of relative water content. Thus, the leaf water content index may be able to estimate average relative water content of canopies when TM4 and TM5 are measured at a known relative water content and fraction of dead leaf material.
Hunt JrER, RockBN ( 1989). Detection of changes in leaf water content using near and middle-infrared reflectances Remote Sensing of Environment, 30, 43-54. DOIURL [本文引用: 2] Detection of plant water stress by remote sensing has been proposed using indices of Near-Infrared (NIR, 0.7–1.3 μm) and Middle-Infrared (MIR, 1.3–2.5 μm) wavelengths. The first objective of this study was to test the ability of the Leaf Water Content Index (LWCI) to determine leaf Relative Water content (RWC) of different species with different leaf morphologies. The second objective was to determine how the Moisture Stress Index (MSI; MIR / NIR) varies with RWC and the Equivalent Water Thickness (EWT). Reflectance factors at 0.82 μm and 1.6 μm were measured on leaves of Quercus agrifolia (sclerophyllous leaves), Liquidambar styraciflua (hardwood deciduous tree leaves), Picea rubens and Picea pungens (conifer needles), and Glycine max (herbaceous dicot leaves) as they dried on a laboratory bench. RWC and EWT were measured concurrently with the reflectance measurements. The results showed that LWCI was equal to RWC for the species tested. However, the results of a sensitivity analysis indicated the reflectances at 1.6 μm for two different RWC must be known for accurate prediction of unknown RWC; thus the LWCI is impractical for field applications. MSI was linearly correlated to RWCwith each species having a different regression equation and to log 10 EWT with data of all species falling on the same regression line. Because EWT is correlated with leaf area index, MSI should also be correlated with leaf area index. Assuming that the linear regression equation of MSI to EWT can be applied to canopies, then the minimum significant change of RWC that can be detected is 52%. For most plants, the natural variation in RWC from water stress is only about 20%, so that we conclude that indices derived from NIR and MIR reflectances cannot be used to remotely-sense water stress.
InoueY, MorinagaS, ShibayamaM ( 1993). Non-destructive estimation of water status of intact crop leaves based on spectral reflectance measurements Japanese Journal of Crop Science, 62, 462-469. DOIURL [本文引用: 3] Abstract Visible and near- and mid- infrared spectral measurements were made on intact and detached leaves of four crop species (Corn, Peanut, Soybean and Wheat) using two spectroradiometers under three different conditions : field measurements under artificial light and solar radiation conditions with and without an integrating sphere, and laboratory measurements with an integrating sphere. In the regions of 1350-1480, 1800-2000, and 2350-2500 nm wavelenghts, measurements of spectral reflectance (ρ) of crop leaves were not possible, even under fully sun-lit conditions due to atmospheric absorption of light in these regions. Relative water content (RWC, %) was well correlated with 1n (ρ1910), ρ1430, and 1n (ρ1650), while water content (WC, H2O mg cm-2) was correlated with ρ1200/ρ1430, ρ1650/ρ1430, ρ800-ρ1200 and ρ1100-ρ1200. Despite very high correlation between those indices and RWC for different crops, no common regression equation was obtained. On the other hand, a common linear relationship was obtained between spectral indices and WC for all four crops irrespective of leaf thickness, chlorophyll content and structure. The first derivative at 1121 nm was also found to be closely related to leaf water status. An obvious spectral shift of inflection point associated with water status was found aroud 2010 nm region. The location of inflection point shifted over a range from 2080 to 1880 nm according to the dehydration of leaves, and the degree of the shift was closely correlated with RWC and WC. Relative leaf water status of intact leaves of drought-stressed and well-watered soybean plants was estimated from spectral measurements in the field.
JacksonRD ( 1985). Spectral response of cotton to suddenly induced water stress International Journal of Remote Sensing, 6, 177-185. DOIURL [本文引用: 1] Spectral responses in eight wavebands (three visible, two near-IR, two mid-IR, and one thermal IR) were measured by repetitively traversing a radiometer over several rows of cotton (Gossypium hirsutum L.). After an initial measurement, the stems of one row (which had previously been tied to wooden dowels) were cut at a point just above the soil. The subsequent dessication of plants within this row was followed by comparing its reflectance and emittance with a control row. All wavebands measured reacted rapidly to stress with the visible and thermal IR showing a larger change than the near-IR. Reflectance changes caused by canopy geometry changes were apparently greater than those caused by leaf physiological and anatomical changes in all but the visible red band. The increase in red reflectance was attributed to a rapid decrease in absorptance by leaf chloroplasts. As expected, the radiometrically determined plant temperatures increased with time after the stress was imposed.
JacquemoudS, BaretF ( 1990). Prospect—A model of leaf optical properties spectra Remote Sensing of Environment, 34, 75-91. DOIURL [本文引用: 3] PROSPECT is a radiative transfer model based of Allen's generalized “plate model” that represents the optical properties of plant leaves from 400 nm to 2500 nm. Scattering is described by a spectral refractive index (n) and a parameter characterizing the leaf mesophyll structure (N). Absorption is modeled using pigment concentration (C a+b), water content (C w), and the corresponding specific spectral absorption coefficients (K a+b and K w). The parameters n, K a+b, and K w have been fitted using experimental data corresponding to a wide range of plant types and status. PROSPECT has been tested successfully on independent data sets. Its inversion allows one to reconstruct, with reasonable accuracy, leaf reflectance, and transmittance features in the 400–2500 nm range by adjusting the three input variables N, C a+b, and C w.
JacquemoudS, UstinS, VerdeboutJ, SchmuckG, AndreoliG, HosgoodB ( 1996). Estimating leaf biochemistry using the PROSPECT leaf optical properties model Remote Sensing of Environment, 56, 194-202. DOIURL [本文引用: 2] The biophysical, biochemical, and optical properties of 63 fresh leaves and 58 dry leaves were measured to investigate the potential of remote sensing to estimate the leaf biochemistry from space. Almost 2000 hemispherical reflectance and transmittance spectra were acquired from 400 nm to 2500 nm using a laboratory spectrophotometer. The amount of chlorophyll, water, protein, cellulose, hemicellulose, lignin, and starch was determined on these leaves using standard wet chemistry techniques. These experimental data were used to improve the PROSPECT model, a simple but effective radiative transfer model that calculates the leaf optical properties with a limited number of input parameters: a structure parameter and the leaf biochemistry. The new model construction mainly consisted in providing specific absorption coefficients for the biochemical constituents; the comparison with absorption spectra of pure materials derived from the literature showed good agreement. In the inversion, however, it was necessary to group some leaf components in order to estimate leaf biochemistry with reasonable accuracy. Predictive power varied with the chemistry variable, wavelengths used in analysis, and whether leaves were fresh or dry. r 2 ranged from 0.39 to 0.88 for predictions on dry leaves; on fresh leaves, water and chlorophyll had high r 2 values, 0.95 and 0.68 respectively, carbon based compounds reasonable r 2 , from 0.50 to 0.88, while the estimation of protein is still at issue.
KramerPJ ( 1983). Water Relations of Plants. New York Press, New York. [本文引用: 2]
KriedemamnPE, BarrsHD ( 1983). Photosynthetic Adaptation to Water Stress and Implication for Drought Resistance Westbiew Press, Boulder. [本文引用: 1]
LiBZ, ZhouGS ( 2014). Advance in the study on drought index Acta Ecologica Sinica, 34, 1043-1052. [本文引用: 1]
LiuC, SunPS, LiuSR ( 2016). A review of plant spectral reflectance response to water physiological changes Chinese Journal of Plant Ecology, 40, 80-91. [本文引用: 1]
MakiM, IshiahraM, TamuraM ( 2004). Estimation of leaf water status to monitor the risk of forest fires by using remotely sensed data Remote Sensing of Environment, 90, 441-450. DOIURL [本文引用: 4] Estimating the water status of vegetation is one of the most important elements in assessing forest fire danger. In this paper, laboratory measurement confirmed a relationship between leaf water status and the normalized difference water index (NDWI), derived from near-infrared and shortwave-infrared spectral data. Two results were confirmed: (a) NDWI is related to equivalent water thickness, and, (b) in addition to NDWI, the quantity of leaf material must be known in order to estimate vegetation dryness. Based on these findings, the authors developed a vegetation dryness index (VDI) to estimate global vegetation water content. VDI values, calculated by using SPOT/VEGETATION data, were applied to data from a 1998 forest fire in the Russian Far East. This led to two results: (a) VDI was useful for detecting areas with a high potential for ignition, and (b) VDI may have been able to detect the fire-spread direction.
MichioS, TsuyoshiA ( 1989). Seasonal visible, near-infrared and mid-infrared spectral of rice canopies in relation to LAI and aboveground dry phytomass Remote Sensing of Environment, 27, 119-127. DOIURL [本文引用: 1] Spectral reflectance factors were measured for paddy rice canopies in the visible (VIS), reflective near-infrared (NIR), and mid-infrared (MIR) wavelength regions. Radiometric and agronomic measurements were performed every other week from 45 days before heading to 64 days after heading in early- and late-planted rice plots consisting of five cultivars. The relation between radiometric data an and the leaf area index (LAI) and above-ground dry phytomass (GDM) was investigated during 11 development periods of 10-day intervals. Reflectance values in the VIS bands were lowest when the panicles emerged, whereas the values at 840 and 1100 nm increased until the time when the grains reached maturity. Reflectances at 1200 and 1650 nm were similar in pattern but less pronounced than at 840 and 1100 nm. Ratios using VIS and NIR reflectances (R 840 / R 560, R 1100 / R 840) for the whole season were associated with 71of the variation in LAI, while the difference between NIR and MIR reflectances (R 1100 - R 1650, R 1100 - R 1200) combined with ratios using VIS and NIR reflectances (R 840 / R 560, R 1100 / R 840) was associated with 93% of the variation in GDM of the paddy rice canopies. Thus, the use of mid-infrared wavelengths may result in improved estimates of seasonal GDM.
MirzaieM, DarvishzadehR, ShakibaA, MatkanAA, AtzbergerC, SkidmoreA ( 2014). Comparative analysis of different uni- and multi-variate methods for estimation of vegetation water content using hyper-spectral measurements International Journal of Applied Earth Observation and Geoinformation, 26, 1-11. DOIURL [本文引用: 6] Assessment of vegetation water content is critical for monitoring vegetation condition, detecting plant water stress, assessing the risk of forest fires and evaluating water status for irrigation. The main objective of this study was to investigate the performance of various mono- and multi-variate statistical methods for estimating vegetation water content (VWC) from hyper-spectral data. Hyper-spectral data is influenced by multi-collinearity because of a large number of (independent) spectral bands being modeled by a small number of (dependent) biophysical variables. Therefore, some full spectrum methods that are known to be suitable for analyzing multi-collinear data set were chosen. Canopy spectral reflectance was obtained with a GER 3700 spectro-radiometer (400–240002nm) in a laboratory setting and VWC was measured by calculating wet/dry weight difference per unit of ground area (g/m 2 ) of each plant canopy ( n 02=0295). Three multivariate statistical methods were applied to estimate VWC: (1) partial least square regression, (2) artificial neural network and (3) principal component regression. They were selected to minimize the problem related to multi-collinearity. For comparison, uni-variate techniques including narrow band ratio water index (RWI), normalized difference water index (NDWI), second soil adjusted vegetation index (SAVI2) and transferred soil adjusted vegetation index (TSAVI) were applied. For each type of vegetation index, all two-band combinations were evaluated to determine the best band combination. Validation of the methods was based on the cross validation procedure and using three statistical indicators: R 2 , RMSE and relative RMSE. The cross-validated results identified PLSR as the regression model providing the most accurate estimates of VWC among the various methods. The result revealed that this model is highly recommended for use with multi-collinear datasets ( R CV 2 = 0.94 mathContainer Loading Mathjax , RRMSE CV 02=020.23). Principal component regression exhibited the lowest accuracy among the multivariate models ( R CV 2 = 0.78 mathContainer Loading Mathjax , RRMSE CV 02=020.41).
MoranMS, ClarkeTR, InoueY, VidalA ( 1994). Estimating crop water deficit using the relation between surface-air temperature and spectral vegetation index Remote Sensing of Environment, 49, 246-263. DOIURL [本文引用: 1] ; ; ; ; USDA, water conservation lab., Phoenix, ETATS-UNISCEMAGREF-ENGREF, remote sensing lab., Montpellier, FRANCE02 0202 02 0202RSEEA702 CongrèsRemote sensing of soils and vegetation. Symposium, Tempe AZ , ETATS-UNIS (1993) 1994,02vol.0249,02n02302(1 p.1/2),02pp.02246-263AnglaisElsevier, New York, NY, ETATS-UNIS02 (1969) (Revue); ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; INIST-CNRS, Cote INIST : 14287,0235400004199403.0090
PeñuelasJ, FilellaI, BielC, SerranoL, SaveR ( 1993). The reflectance at the 950-970 nm region as an indicator of plant water status International Journal of Remote Sensing, 14, 1887-1905. DOIURL [本文引用: 3]
PeñuelasJ, FilellaI, SweeanoL ( 1996). Cell wall elastivity and Water Index (R970 nm/R900 nm) in wheat under different nitrogen availabilities International Journal of Remote Sensing, 7, 373-382. DOIURL [本文引用: 2] New data showing the importance of cell wall elasticity in the expression of the Water Index (WI) (R970/R900) as an indicator of plant water status are presented. We studied wheat under five different nitrogen (N) fertilization treatments (0 to 200kg ha-1) to test N-availability effects on tissue structural changes such as cell wall composition and elasticity, and the corresponding effects on WI. Although water was amply supplied in all the plots, Wl, CWSI (Crop Water Stress Index) and ST (canopy minus air temperature) were all highest in the N-0 (no fertilization) treatment. Plants in this treatment had the most xeromorphic characteristics. Their specific leaf weight (SLAV) and leaf cellulose contents were higher and their cell wall elasticities were lower than in the other N treatments. WI was a useful water status indicator (even of mild water stress conditions) at ground level when elasticity was low, WI may also become an indicator of cell wall elasticity of leaves when plant water status is known.
PriceJC ( 1990). Using spatial context in satellite data to infer regional scale evaportranspiration IEEE Transactions on Geoscience and Remote Sensing, 28, 940-948. DOIURL [本文引用: 2] Several methods have been used to estimate regional scale evapotranspiration from satellite thermal infrared measurements. These procedures assume knowledge of surface properties such as surface roughness, albedo, vegetation characteristics, etc. In many areas of the earth these parameters are not accurately known due to the rapidity of change of vegetation, lack of adequate geographical data b...
QiY, DennisonPE, JollyWM, KroppRC, BrewerSC ( 2014). Spectroscopic analysis of seasonal changes in live fuel moisture content and leaf dry mass Remote Sensing of Environment, 150, 198-206. DOIURL [本文引用: 1] Live fuel moisture content (LFMC), the ratio of water mass to dry mass contained in live plant material, is an important fuel property for determining fire danger and for modeling fire behavior. Remote sensing estimation of LFMC often relies on an assumption of changing water and stable dry mass over time. Fundamental understanding of seasonal variation in plant water and dry mass is needed to explain the spectral expression of LFMC changes over time. We conducted a five-month experiment to continuously measure field LFMC samples, biochemical components of dry matter, and leaf spectroscopic data for two species common in the western U.S., lodgepole pine ( Pinus contorta Douglas ex Loudon) and big sagebrush ( Artemisia tridentata Nutt). Our results showed that new lodgepole pine needles initially had higher LFMC and a smaller proportion of dry mass, but differences between new and old needles converged as the new needles matured. New needle dry mass had strong temporal trends, and dry mass explained more variation in LFMC than water in both new and old needles. Sagebrush leaves exhibited decreasing trends in LFMC, but water and dry mass comparably contributed to LFMC seasonal variation. Spectroscopic analysis using partial least squares regression (PLSR) showed good modeling accuracy for LFMC temporal variation in new needles (R 2 02=020.94, RMSE02=025.84%), old needles (R 2 02=020.72, RMSE02=023.51%), and sagebrush (R 2 02=020.91, RMSE02=0221.03%). Spectral variation in response to changing LFMC and dry mass was difficult to isolate from broader spectral trends due to chlorophyll absorption, leaf structure, water absorption, and co-varied biochemical components. Our results stress cautious spectral interpretation and wavelength selection for LFMC estimation in some species (e.g. lodgepole pine), since temporal changes in spectra may dominantly reflect temporal variation in dry mass, pigments, and/or structure rather than water content. Since new needles should have stronger spectral expression at the canopy scale, differing temporal trends in new and old lodgepole pine needles provides an additional complicating factor for remote monitoring of LFMC.
RenH, ZhouG ( 2014). Estimating aboveground green biomass in desert steppe using band depth indices Biosystems Engineering, 127, 67-78. DOIURL [本文引用: 1] 61Band depth indices are used to estimate green biomass of desert steppe.61The efficacies of different indices are compared based on experimental data.61The accuracy of BD at 69802nm is higher than that of any other indices.61BDR, NBDI, and BNA are not reliable indicators of biomass in desert steppe.61BDmax and BDarea can be used to monitor biomass with reasonable accuracy.
RiddMK ( 1995). Exploring a V-I-S (vegetation-impervious surface-soil) model for urban ecosystem analysis through remote sensing: Comparative anatomy for citied International Journal of Remote Sensing, 16, 2165-2185. DOIURL [本文引用: 1] Growing interest in urban systems as ecological entities calls for some standards in parameterizing biophysical composition of urban environments. A vegetation-impervious surface-soil ( V-I-S) model is presented as a possible basis for standardization. The V-I-S model may serve as a foundation for characterizing urban/near-urban environments universally, and for comparison of urban morphology within and between cities. Inasmuch as the model may be driven by satellite digital data, it may serve as a global model of urban ecosystem analysis and comparison world-wide. The V-I-S model may prove useful for urban change detection and growth modelling, for environmental impact analysis from urbanization, for energy- and water-related investigations, and for certain dimensions of human ecosystem analysis of the city as well.
RollinEM, MiltonEJ ( 1998). Processing of high spectral resolution reflectance data for the retrieval of canopy water content information Remote Sensing of Environment, 65, 86-92. DOIURL [本文引用: 2] This article examines how different processing, in particular different degrees of smoothing, affect the extraction of biophysical information from high spectral resolution data. Spectral reflectance data collected during the EISAC 89 Campaign from an experimental grassland site on Tadham Moor, Somerset, United Kingdom were used for the analysis, together with canopy biomass, chlorophyll, and water content variables. The analysis focuses mainly on the correlation between percentage water content per unit area of canopy and spectral parameters across the two water absorption features, around 940 nm and 1150 nm. Correlation analysis revealed that both the strength of the peak correlation between the first derivative of reflectance and water content and its wavelength position were sensitive to the degree of smoothing for the 1150 nm feature, although this was not the case for the 940 nm water absorption feature. This sensitivity is attributed to the fact that different levels of smoothing emphasize different spectral features across a wavelength region where the first derivative of reflectance and the biophysical variable are generally highly correlated. The effect emphasizes that the exact position of peak correlation between these two variables should be interpreted with caution, especially across spectral regions where the correlation is generally high. A simple reflectance ratio based on the relative depth of the water absorption feature was found to be more closely related to canopy water content and insensitive to the degree of spectral smoothing.
RunningSW, GowerST ( 1991). Forest-BGC, a general model of forest ecosystem processes for regional applications II. Dynamic carbon allocation and nitrogen budgets Tree Physiology, 9, 147-160. DOIURLPMID [本文引用: 1] A new version of the ecosystem process model FOREST-BGC is presented that uses stand water and nitrogen limitations to alter the leaf/root/stem carbon allocation fraction dynamically at each annual iteration. Water deficit is defined by integrating a daily soil water deficit fraction annually. Current nitrogen limitation is defined relative to a hypothetical optimum foliar N pool, computed as maximum leaf area index multiplied by maximum leaf nitrogen concentration. Decreasing availability of water or nitrogen, or both, reduces the leaf/root carbon partitioning ratio. Leaf and root N concentrations, and maximum leaf photosynthetic capacity are also redefined annually as functions of nitrogen availability. Test simulations for hypothetical coniferous forests were performed for Madison, WI and Missoula, MT, and showed simulated leaf area index ranging from 4.5 for a control stand at Missoula, to 11 for a fertilized stand at Madison, with Year 50 stem carbon biomasses of 31 and 128 Mg ha(-1), respectively. Total nitrogen incorporated into new tissue ranged from 34 kg ha(-1) year(-1) for the unfertilized Missoula stand, to 109 kg ha(-1) year(-1) for the fertilized Madison stand. The model successfully showed dynamic annual carbon partitioning controlled by water and nitrogen limitations.
RunningSW, NemaniRR ( 1991). Regional hydrologic and carbon balance responses of forests resulting from potential climate change Climatic Change, 19, 349-368. DOIURL [本文引用: 1] The projected response of coniferous forests to a climatic change scenario of doubled atmospheric CO 2 , air temperature of +4 °C, and +10% precipitation was studied using a computer simulation model of forest ecosystem processes. A topographically complex forested region of Montana was simulated to study regional climate change induced forest responses. In general, increases of 10–20% in LAI, and 20–30% in evapotranspiration (ET) and photosynthesis (PSN) were projected. Snowpack duration decreased by 19–69 days depending on location, and growing season length increased proportionally. However, hydrologic outflow, primarily fed by snowmelt in this region, was projected to decrease by as much as 30%, which could virtually dry up rivers and irrigation water in the future. To understand the simulated forest responses, and explore the extent to which these results might apply continentally, seasonal hydrologic partitioning between outflow and ET, PSN, respiration, and net primary production (NPP) were simulated for two contrasting climates of Jacksonville, Florida (hot, wet) and Missoula, Montana (cold, dry). Three forest responses were studied sequentially from; climate change alone, addition of CO 2 induced tree physiological responses of-30% stomatal conductance and +30% photosynthetic rates, and finally with a reequilibration of forest leaf area index (LAI), derived by a hydrologic equilibrium theory. NPP was projected to increase 88%, and ET 10%, in Missoula, MT, yet dcrease 5% and 16% respectively for Jacksonville, FL, emphasizing the contrasting forest responses possible with future climatic change.
SandholtI, RasmussenK, AndersenJ ( 2002). A simple interpretation of the surface temperature/vegetation index space for assessment of surface moisture status Remote Sensing of Environment, 79, 213-224. DOIURL [本文引用: 1] A simplified land surface dryness index (Temperature egetation Dryness Index, TVDI) based on an empirical parameterisation of the relationship between surface temperature ( T s) and vegetation index (NDVI) is suggested. The index is related to soil moisture and, in comparison to existing interpretations of the T s/NDVI space, the index is conceptually and computationally straightforward. It is based on satellite derived information only, and the potential for operational application of the index is therefore large. The spatial pattern and temporal evolution in TVDI has been analysed using 37 NOAA-AVHRR images from 1990 covering part of the Ferlo region of northern, semiarid Senegal in West Africa. The spatial pattern in TVDI has been compared with simulations of soil moisture from a distributed hydrological model based on the MIKE SHE code. The spatial variation in TVDI reflects the variation in moisture on a finer scale than can be derived from the hydrological model in this case.
ShenY, NiuZ, YanCY ( 2005). Estimation models for vegetation water content at both leaf and canopy levels Chinese Journal of Applied Ecology, 16, 1218-1223. URL [本文引用: 2] 利用LOPEX'93数据库中67个鲜叶片含水量(Cw)和光谱反射率实测数据,基于光谱指数法,在叶片层次,用47个随机样本建立Cw与不同光谱指数的统计模型,并用另外20个样本验证.结果表明,Cw的两种表征形式相对含水量FMC和等价水深EWT在提取叶片Cw时差异较大,EWT与各光谱指数的相关性较FMC高,但FMC对叶片Cw的反演精度高于EWT.而反演精度更高的是基于最优子集回归建立的光谱指数线性模型.Ratio975是叶片层次提取Cw的普适光谱指数.冠层层次,利用PROSPECT+SAILH耦合模型,模拟在不同叶面积指数LAI和Cw下的冠层光谱.为了剔除背景影响,更好地提取冠层Cw,提出用近红外和短波红外波段反射率构造土壤可调节水分指数(SAWI),该指数与其他光谱指数的比值能明显地剔除土壤背景影响,更准确地提取冠层Cw.Ratio975的改进型光谱指数(Ratio975-0.96)/(SAWI+0.2)能用来提取叶面积指数LAI从0.3到8.0,Cw从0.0001cm到0.07cm的冠层Cw,研究表明精度较高. [ 沈艳, 牛铮, 颜春燕 ( 2005). 植被叶片及冠层层次含水量估算模型的建立 应用生态学报, 16, 1218-1223.] URL [本文引用: 2] 利用LOPEX'93数据库中67个鲜叶片含水量(Cw)和光谱反射率实测数据,基于光谱指数法,在叶片层次,用47个随机样本建立Cw与不同光谱指数的统计模型,并用另外20个样本验证.结果表明,Cw的两种表征形式相对含水量FMC和等价水深EWT在提取叶片Cw时差异较大,EWT与各光谱指数的相关性较FMC高,但FMC对叶片Cw的反演精度高于EWT.而反演精度更高的是基于最优子集回归建立的光谱指数线性模型.Ratio975是叶片层次提取Cw的普适光谱指数.冠层层次,利用PROSPECT+SAILH耦合模型,模拟在不同叶面积指数LAI和Cw下的冠层光谱.为了剔除背景影响,更好地提取冠层Cw,提出用近红外和短波红外波段反射率构造土壤可调节水分指数(SAWI),该指数与其他光谱指数的比值能明显地剔除土壤背景影响,更准确地提取冠层Cw.Ratio975的改进型光谱指数(Ratio975-0.96)/(SAWI+0.2)能用来提取叶面积指数LAI从0.3到8.0,Cw从0.0001cm到0.07cm的冠层Cw,研究表明精度较高.
TangYL, HuangJF ( 2001). Study on hyperspectral remote sensing in agriculture Remote Sensing Technology and Application, 16, 248-251. DOIURL [本文引用: 1] 高光谱遥感是对地观测强有力的工具和现代遥感的重要发展方向 ,在农业上具有广泛的应用前景。简要介绍了农业高光谱遥感应用研究的原理及现状 ,存在的问题及发展趋势。 [ 唐延林, 黄敬峰 ( 2001). 农业高光谱遥感研究的现状与发展趋势 遥感技术与应用, 16, 248-251.] DOIURL [本文引用: 1] 高光谱遥感是对地观测强有力的工具和现代遥感的重要发展方向 ,在农业上具有广泛的应用前景。简要介绍了农业高光谱遥感应用研究的原理及现状 ,存在的问题及发展趋势。
TianQJ, GongP, ZhaoCJ, GuoXW ( 2000). The feasibility of diagnosing wheat water status by using spectral reflectance Chinese Science Bulletin, 45, 2645-2650. DOIURL [本文引用: 1] 用地物光谱仪对大田内１１０个小麦叶片进行了光谱反射率测试，采用光谱归一化技术对小麦叶片的光谱特征吸收峰深度和面积进行定量描述和计算，同时测定了小麦叶片的相对水分含量，研究发现小麦叶片相对水分含量与光谱反射率在１４５０ｎｍ附近水的特征吸收峰深度和面积呈现良好的线笥正相关关系，通过光谱反射率可以诊断小麦缺水状况，对基于地物光谱仪的改进进行了讨论，提出开发小麦水分活体定量测定的可行性技术。 [ 田庆久, 宫鹏, 赵春江, 郭晓维 ( 2000). 用光谱反射率诊断小麦水分状况的可行性 科学通报, 45, 2645-2650.] DOIURL [本文引用: 1] 用地物光谱仪对大田内１１０个小麦叶片进行了光谱反射率测试，采用光谱归一化技术对小麦叶片的光谱特征吸收峰深度和面积进行定量描述和计算，同时测定了小麦叶片的相对水分含量，研究发现小麦叶片相对水分含量与光谱反射率在１４５０ｎｍ附近水的特征吸收峰深度和面积呈现良好的线笥正相关关系，通过光谱反射率可以诊断小麦缺水状况，对基于地物光谱仪的改进进行了讨论，提出开发小麦水分活体定量测定的可行性技术。
TianYC, ZhuY, CaoWX, DaiTB ( 2004). Relationship between canopy reflectance and plant water status of wheat Chinese Journal of Applied Ecology, 15, 2072-2076. URL [本文引用: 1] 研究了不同土壤水、氮条件下小麦冠层光谱反射特征与叶片和植株水分状况的相关性．结果表明，在小麦主要生育期，冠层叶片含水率与460～510、610～680和1480～1500nm波段范围内的光谱反射率有较高的相关性，植株含水率与810～870nm波段范围内的光谱反射率密切相关．在整个生长期内，小麦冠层叶片含水率与460～1500nm波段范围内的光谱反射率均有良好相关性，植株含水率与560～1480nm波段范围内光谱反射率的相关性均达到极显著水平．冠层叶片(CL)、上层叶(UL)和下层叶片(LL)含水率与光谱指数的相关程度为CL>LL>UL．冠层叶片和植株含水率与比值指(R(610，560))和光谱指数(R(610，560)／ND(810，610))呈极显著线性负相关，与归一化指数((R810-R610)／(R810+R610))呈极显著线性正相关．其中，用光谱指数(R(610，560)／ND(810，610))监测不同生育期小麦冠层叶片和植株含水率的效果最好。 [ 田永超, 朱艳, 曹卫星, 戴廷波 ( 2004). 小麦冠层反射光谱与植株水分状况的关系 应用生态学报, 15, 2072-2076.] URL [本文引用: 1] 研究了不同土壤水、氮条件下小麦冠层光谱反射特征与叶片和植株水分状况的相关性．结果表明，在小麦主要生育期，冠层叶片含水率与460～510、610～680和1480～1500nm波段范围内的光谱反射率有较高的相关性，植株含水率与810～870nm波段范围内的光谱反射率密切相关．在整个生长期内，小麦冠层叶片含水率与460～1500nm波段范围内的光谱反射率均有良好相关性，植株含水率与560～1480nm波段范围内光谱反射率的相关性均达到极显著水平．冠层叶片(CL)、上层叶(UL)和下层叶片(LL)含水率与光谱指数的相关程度为CL>LL>UL．冠层叶片和植株含水率与比值指(R(610，560))和光谱指数(R(610，560)／ND(810，610))呈极显著线性负相关，与归一化指数((R810-R610)／(R810+R610))呈极显著线性正相关．其中，用光谱指数(R(610，560)／ND(810，610))监测不同生育期小麦冠层叶片和植株含水率的效果最好。
UstinSL, RobertsDA, GamonJA, AsnerGP, GreenRO ( 2004). Using imaging spectroscopy to study ecosystem processes and properties BioScience, 54, 523-534. DOIURL [本文引用: 1] Remote sensing data provide essential input for today's climate and ecosystem models. It is generally agreed that many model processes are not accurately depicted by current remotely sensed indices of vegetation and that new observational capabilities are needed at different spatial and spectral scales to reduce uncertainty. Recent advances in materials and optics have allowed the development of smaller, more stable, accurately calibrated imaging spectrometers that can quantify biophysical properties on the basis of the spectral absorbing and scattering characteristics of the land surface. Airborne and spaceborne imaging spectrometers, which measure large numbers (hundreds) of narrow spectral bands, are becoming more widely available from government and commercial sources; thus, it is increasingly feasible to use data from imaging spectroscopy for environmental research. In contrast to multispectral sensors, imaging spectroscopy produces quantitative estimates of biophysical absorptions, which can be used to improve scientific understanding of ecosystem functioning and properties. We present the recent advances in imaging spectroscopy and new capabilities for using it to quantify a range of ecological variables.
VerhoefW ( 1984). Light scattering by leaf layers with application to canopy reflectance modeling: The SAIL model Remote Sensing of Environment, 16, 125-141. DOIURL [本文引用: 1] The scattering and extinction coefficients of the SAIL canopy reflectance model are derived for the case of a fixed arbitrary leaf inclination angle and a random leaf azimuth distribution. The SAIL model includes the uniform model of G. H. Suits as a special case and its main characteristics are that canopy variables such as leaf area index and the leaf inclination distribution function are used as input parameters and that it provides more realistic angular profiles of the directional reflectance as a function of the view angle or the solar zenith angle.
WangJH, ZhaoCJ, GuoXW, HuanWJ, TianQJ ( 2000). Study on the water content of wheat leaves by the remote sensing Acta Agriculturae Boreali-Sinica, 15(4), 68-72. DOIURLMagsci [本文引用: 2] 应用地物光谱仪探讨了小麦叶片含水量对近红外（NIR）波段光谱吸收特征参量的影响。结果表明：1.65~1.85 μm间的光谱反射率与小麦叶片的含水量呈显著负相关，而且该波段在大气窗口之内，受大气层水的干扰较小，可作为航空或卫星遥感探测指标应用。根据大量观测数据建立了叶片含水量与吸收深度及吸收面积间的线性相关关系和回归方程式，从而提出一种利用光谱反射率诊断小麦叶片水分状况的遥感方法。 [ 王纪华, 赵春江, 郭晓维, 黄文江, 田庆久 ( 2000). 利用遥感方法诊断小麦叶片含水量的研究 华北农学报, 15(4), 68-72.] DOIURLMagsci [本文引用: 2] 应用地物光谱仪探讨了小麦叶片含水量对近红外（NIR）波段光谱吸收特征参量的影响。结果表明：1.65~1.85 μm间的光谱反射率与小麦叶片的含水量呈显著负相关，而且该波段在大气窗口之内，受大气层水的干扰较小，可作为航空或卫星遥感探测指标应用。根据大量观测数据建立了叶片含水量与吸收深度及吸收面积间的线性相关关系和回归方程式，从而提出一种利用光谱反射率诊断小麦叶片水分状况的遥感方法。
WangJH, ZhaoCJ, GuoXW, TianQJ ( 2001). Study on the water status of the wheat leaves diagnosed by the spectral reflectance Scientia Agricultura Sinica, 34, 104-107. [本文引用: 1]
YebraM, DennisonPE, ChuviecoE, RiañoD, ZylstraP, Hunt JrER, DansonFM, QiY, JurdaoS ( 2013). A global review of remote sensing of live fuel moisture content for fire danger assessment: Moving towards operational products Remote Sensing of Environment, 136, 455-468. DOIURL [本文引用: 2] One of the primary variables affecting ignition and spread of wildfire is fuel moisture content (FMC). Live FMC (LFMC) is responsive to long term climate and plant adaptations to drought, requiring remote sensing for monitoring of spatial and temporal variations in LFMC. Liquid water has strong absorption features in the near- and shortwave-infrared spectral regions, which provide a physical basis for direct estimation of LFMC. Complexity introduced by biophysical and biochemical properties at leaf and canopy scales presents theoretical and methodological problems that must be addressed before remote sensing can be used for operational monitoring of LFMC. The objective of this paper is to review the use of remotely sensed data for estimating LFMC, with particular concern towards the operational use of LFMC products for fire risk assessment. Relationships between LFMC and fire behavior have been found in fuel ignition experiments and at landscape scales, but the complexity of fire interactions with fuel structure has prevented linking LFMC to fire behavior at intermediate scales. Changes in LFMC have both direct (liquid water absorption) and indirect (pigment and structural changes) impacts on spectral reflectance. The literature is dominated by studies that have used statistical (empirical) and physical model-based methods applied to coarse resolution data covering the visible, near infrared, and/or shortwave infrared regions of the spectrum. Empirical relationships often have the drawback of being site-specific, while the selection and parameterization of physically-based algorithms are far more complex. Challenges remain in quantifying error of remote sensing-based LFMC estimations and linking LFMC to fire behavior and risk. The review concludes with a list of priority areas where advancement is needed to transition remote sensing of LFMC to operational use.
YiQ, BaoA, WangQ, ZhaoJ ( 2013). Estimation of leaf water content in cotton by means of hyperspectral indices Computers and Electronics in Agriculture, 90, 144-151. DOIURL [本文引用: 6] The knowledge of vegetation water conditions can contribute to drought assessment. Remote sensing has a proven ability to assess vegetation properties. In this study, all two-band combinations (350-2500 nm) in the ratio type of vegetation index (RVI) and the normalized difference type of vegetation index (NDVI) were performed on cotton leaf raw spectral reflectance (R) and the first derivative reflectance (DR). The correlation coefficient (r) between all two-band combinations and two leaf water parameters (EWT: equivalent water thickness, and FMC: fuel moisture content) were determined, and the results of this comprehensive analysis were presented by matrix plots. Band centers (lambda(1) and lambda(2)) and band widths (Delta lambda(1) and Delta lambda(2)) that combine to form the best indices were identified for EWT and FMC through matrix plots. Then the evaluation of the predictive power of three predictors, i.e. single narrow band reflectance, the widely used published water indices and the best band combination indices, were performed. The results shown that the new indices DR1647/DR1133 and DR1653/DR1687, proposed by two-band combinations, were considered as the optimal indices for EWT and FMC estimation, respectively. The models based on these two best combination indices could explain 58% and 67% variability in EWT and FMC, respectively. Besides, bands with center wavelengths in region from 950 nm to 1100 nm, and 1650 nm to 1750 nm were represented almost all selected bands. The study should further our understanding of the relationships between leaf water content and hyperspectral reflectance. (C) 2012 Elsevier B.V. All rights reserved.
YiQ, WangF, BaoA, JiapaerG ( 2014). Leaf and canopy water content estimation in cotton using hyperspectral indices and radiative transfer models International Journal of Applied Earth Observation and Geoinformation, 33, 67-75. DOIURL [本文引用: 7] In present study some vegetation indices for estimating leaf EWT and EWTcanopy were investigated using simulations and field measurements. Leaf and canopy spectral reflectance as well as leaf EWT and EWTcanopy were measured in cotton during the growing seasons of 2010 and 2011. The PROSPECT-5 model was coupled with the SAILH model to explore the performance of water-related vegetation indices for leaf EWT and EWTcanopy estimation. The vegetation indices evaluated were published formulations and new simple ratio vegetation indices formulated with wavebands at 1060nm and 1640nm. The sensitivities of these indices to leaf internal structural N and LAI effects were assessed. Simulation results indicated that all of the water-related vegetation indices were insensitive to leaf internal structural N, with the highest coefficient of determination R2<0.15 and the proposed index SR1640 (R1060/R1640) and published index SR2 (R1070/R1340) showed the lowest relationships (R2<0.35) with LAI of all the vegetation indices. Furthermore, coefficients of determination between simulated leaf EWT as well as EWTcanopy and vegetation indices tested revealed that the new simple-ratio vegetation indices proposed in this study (SR1060: R1640/R1060 and SR1640) were found to be significantly related with leaf EWT (R2>0.9; P<0.001) and EWTcanopy (R2>0.8; P<0.001). Results obtained with field measurements were in agreement with simulation results, with the coefficient of determination R2=0.5 (P<0.001) for leaf EWT and R2=0.57 (P<0.001) for EWTcanopy by the new simple ratio indices. This study provides a new candidate for leaf EWT and EWTcanopy estimation using hyperspectral vegetation indices.
YilmazMT, Hunt JrER, GoinsLD, UstinSL, VanderbiltVC, JacksonTJ ( 2008). Vegetation water content during SMEX04 from ground data and Landsat 5 Thematic Mapper imagery Remote Sensing of Environment, 112, 350-362. DOIURL [本文引用: 1] Vegetation water content is an important parameter for retrieval of soil moisture from microwave data and for other remote sensing applications. Because liquid water absorbs in the shortwave infrared, the normalized difference infrared index (NDII), calculated from Landsat 5 Thematic Mapper band 4 (0.76–0.9002μm wavelength) and band 5 (1.55–1.6502μm wavelength), can be used to determine canopy equivalent water thickness (EWT), which is defined as the water volume per leaf area times the leaf area index (LAI). Alternatively, average canopy EWT can be determined using a landcover classification, because different vegetation types have different average LAI at the peak of the growing season. The primary contribution of this study for the Soil Moisture Experiment 2004 was to sample vegetation for the Arizona and Sonora study areas. Vegetation was sampled to achieve a range of canopy EWT; LAI was measured using a plant canopy analyzer and digital hemispherical (fisheye) photographs. NDII was linearly related to measured canopy EWT with an R 2 of 0.601. Landcover of the Arizona, USA, and Sonora, Mexico, study areas were classified with an overall accuracy of 70% using a rule-based decision tree using three dates of Landsat 5 Thematic Mapper imagery and digital elevation data. There was a large range of NDII per landcover class at the peak of the growing season, indicating that canopy EWT should be estimated directly using NDII or other shortwave-infrared vegetation indices. However, landcover classifications will still be necessary to obtain total vegetation water content from canopy EWT and other data, because considerable liquid water is contained in the non-foliar components of vegetation.
YuanWP, ZhouGS ( 2004). Theoretical study and research prospect on drought indices Advances in Earth Science, 19, 982-991. DOIURL [本文引用: 1] 干旱作为最严重的气象灾害之一,已经对我国社会经济和人民生活造成严重影响.尽管关于干旱和干旱指标已有大量研究,但是由于干旱自身的复杂特性和对社会影响的广泛性,干旱指标都是建立在特定的地域和时间范围内,难以准确反映干旱发生的内在机理.为此有必要对干旱定义及国内外主要的干旱指标加以综述和评价,为干旱的监测和评估,特别是为全球变化中的气候-植被关系研究提供方法和依据.将干旱分为4种类型:气象干旱、农业干旱、水文干旱和社会经济干旱,并对当前国内外主要的干旱指标进行介绍,指出了其适用范围,并在归纳现有干旱指标不足的基础上提出了干旱指标的研究方向和任务. [ 袁文平, 周广胜 ( 2004). 干旱指标的理论分析与研究展望 地球科学进展, 19, 982-991.] DOIURL [本文引用: 1] 干旱作为最严重的气象灾害之一,已经对我国社会经济和人民生活造成严重影响.尽管关于干旱和干旱指标已有大量研究,但是由于干旱自身的复杂特性和对社会影响的广泛性,干旱指标都是建立在特定的地域和时间范围内,难以准确反映干旱发生的内在机理.为此有必要对干旱定义及国内外主要的干旱指标加以综述和评价,为干旱的监测和评估,特别是为全球变化中的气候-植被关系研究提供方法和依据.将干旱分为4种类型:气象干旱、农业干旱、水文干旱和社会经济干旱,并对当前国内外主要的干旱指标进行介绍,指出了其适用范围,并在归纳现有干旱指标不足的基础上提出了干旱指标的研究方向和任务.
ZhanZM, QinQM, GhulamA, WangDD ( 2006). A new method monitoring soil moisture based on NIR-Red spectral space Science in China Series D: Earth Sciences, 36, 1020-1026. DOIURL [本文引用: 1] 干旱是一种频繁发生的自然灾害,而土壤水分作为干旱监测最重要的指标,一直成为干旱遥感监测研究的重点内容.利用经过几何精校正和大气校正的ETM+近红外(Nir)、红光(Red)波段反射率建立Nir-Red光谱特征空间,根据土壤水分在该特征空间的分布规律,提出了遥感监测土壤水分的新方法,并建立了基于Nir-Red光谱特征空间的土壤水分监测模型(SMMRS).利用野外测定的不同深度土壤水分数据验证了SMMRS模型.计算结果表明SMMRS模型观测值变化曲线和实测土壤水分变化趋势保持一致,与5cm和0~20cm平均土壤水分相关系数分别为0.80和0.87.认为基于Nir-Red光谱特征空间的SMMRS简单 [ 詹志明, 秦其明, 阿布都瓦斯提•吾拉木, 汪冬冬 ( 2006). 基于NIR-Red光谱特征空间的土壤水分监测新方法 中国科学D辑: 地球科学, 36, 1020-1026.] DOIURL [本文引用: 1] 干旱是一种频繁发生的自然灾害,而土壤水分作为干旱监测最重要的指标,一直成为干旱遥感监测研究的重点内容.利用经过几何精校正和大气校正的ETM+近红外(Nir)、红光(Red)波段反射率建立Nir-Red光谱特征空间,根据土壤水分在该特征空间的分布规律,提出了遥感监测土壤水分的新方法,并建立了基于Nir-Red光谱特征空间的土壤水分监测模型(SMMRS).利用野外测定的不同深度土壤水分数据验证了SMMRS模型.计算结果表明SMMRS模型观测值变化曲线和实测土壤水分变化趋势保持一致,与5cm和0~20cm平均土壤水分相关系数分别为0.80和0.87.认为基于Nir-Red光谱特征空间的SMMRS简单
ZhangJH, GuoWJ, YaoFM ( 2007). The study on vegetation water content estimating model based on remote sensing technique Journal of Basic Science and Engineering, 15, 45-53. DOIURL [本文引用: 3] 植被水分含量的遥感测定对农、林业和水文研究具有重要的意义，对于植被干旱评估也十分重要．研究表明，在叶片尺度上建立400-2500nm的反射率数据与表征叶水分含量的参数，如EWT（等价水厚度）与FMC（叶片相对水分含量）之间存在紧密的相关关系；在冠层水平上，植被水分与光谱指数存在很好的相关关系．归一化水分指数（NDWI）（R860-R1240）／（R860＋R1240）等能较好地反演植被冠层的水分含量．同时，本文对辐射传输模型及其与植被水分指数结合对植被水分反演的应用也进行了讨论；从利用高光谱站台辐射传输模型（如PROSPECT等）进行植被水分反演的角度，对植被水分监测进行评述．最后对利用多角度和偏振光技术定量反演植被水分和临测旱情的研究提出展望。 [ 张佳华, 郭文娟, 姚凤梅 ( 2007). 植被水分遥感监测模型的研究 应用基础与工程科学学报, 15, 45-53.] DOIURL [本文引用: 3] 植被水分含量的遥感测定对农、林业和水文研究具有重要的意义，对于植被干旱评估也十分重要．研究表明，在叶片尺度上建立400-2500nm的反射率数据与表征叶水分含量的参数，如EWT（等价水厚度）与FMC（叶片相对水分含量）之间存在紧密的相关关系；在冠层水平上，植被水分与光谱指数存在很好的相关关系．归一化水分指数（NDWI）（R860-R1240）／（R860＋R1240）等能较好地反演植被冠层的水分含量．同时，本文对辐射传输模型及其与植被水分指数结合对植被水分反演的应用也进行了讨论；从利用高光谱站台辐射传输模型（如PROSPECT等）进行植被水分反演的角度，对植被水分监测进行评述．最后对利用多角度和偏振光技术定量反演植被水分和临测旱情的研究提出展望。
ZhangJH, XuY, YaoFM, WangPJ, GuoWJ, LiL, YangLM ( 2010). Advances in estimation methods of vegetation water content based on optical remote sensing techniques Science China Technological Sciences, 53, 1159-1167. DOIURL [本文引用: 1] Quantitative estimation of vegetation water content (VWC) using optical remote sensing techniques is helpful in forest fire assessment, agricultural drought monitoring and crop yield estimation. This paper reviews the research advances of VWC retrieval using spectral reflectance, spectral water index and radiative transfer model (RTM) methods. It also evaluates the reliability of VWC estimation using spectral water index from the observation data and the RTM. Focusing on two main definitions of VWC he fuel moisture content (FMC) and the equivalent water thickness (EWT), the retrieval accuracies of FMC and EWT using vegetation water indices are analyzed. Moreover, the measured information and the dataset are used to estimate VWC, the results show there are significant correlations among three kinds of vegetation water indices (i.e., WSI, NDII, NDWI 1640 , WI/NDVI) and canopy FMC of winter wheat ( n =45). Finally, the future development directions of VWC detection based on optical remote sensing techniques are also summarized.
ZhangJH, LiL, YaoFM ( 2010). Progress in retrieving vegetation water content under different vegetation coverage condition based on remote sensing spectral information Spectroscopy and Spectral Analysis, 30, 1638-1642. DOIURL [本文引用: 1] 综述了基于遥感光谱信息的植被水分信号提取的研究进展,包括直接利用光谱反射率反演植被水分 信息到建立植被水分指数（WI）,再发展至利用辐射传输模型来获取植被冠层水分信息。着重评述了针对低植被覆盖条件下的提取其冠层水分信息的方法,包括利 用冠层生理参数估算植被水分信号;基于去除土壤背景影响的光谱植被水分指数或辐射传输模型估算植被水分信息,以及基于多角度的星-地观测提取稀疏条件下的 植被水分信息。最后讨论了针对提取低覆盖植被冠层水分信息方法的可能发展趋势。 [ 张佳华, 李莉, 姚凤梅 ( 2010). 遥感光谱信息提取不同覆盖下植被水分信号的研究进展 光谱学与光谱分析, 30, 1638-1642.] DOIURL [本文引用: 1] 综述了基于遥感光谱信息的植被水分信号提取的研究进展,包括直接利用光谱反射率反演植被水分 信息到建立植被水分指数（WI）,再发展至利用辐射传输模型来获取植被冠层水分信息。着重评述了针对低植被覆盖条件下的提取其冠层水分信息的方法,包括利 用冠层生理参数估算植被水分信号;基于去除土壤背景影响的光谱植被水分指数或辐射传输模型估算植被水分信息,以及基于多角度的星-地观测提取稀疏条件下的 植被水分信息。最后讨论了针对提取低覆盖植被冠层水分信息方法的可能发展趋势。
ZhangF, JohnR, ZhouG, ShaoC, ChenJ ( 2014). Estimating canopy characteristics of Inner Mongolia’s grasslands from field spectrometry Remote Sensing, 6, 2239-2254. DOIURL
ZhangF, ZhouG ( 2015). Estimation of canopy water content by means of hyperspectral indices based on drought stress gradient experiments of maize in the North Plain China Remote Sensing, 7, 15203-15223. DOIURL [本文引用: 2] Here, we conducted drought stress gradient experiments of maize, and used ten water content related vegetation indices (VIs) to estimate widely variable canopy water content (CWC) and mean leaf equivalent water thickness at canopy level (\({\overline{EWT}}\)) based on in situ measurements of Lambertian equivalent reflectance and important biological and environmental factors during the 2013 2014 growing seasons in the North China Plain. Among ten VIs, the performances of green chlorophyll index (CIgreen), red edge chlorophyll index (CIred edge), and the red edge normalized ratio (NRred edge) were most sensitive to the variations of CWC and \({\overline{EWT}}\). Simulated drought in two differently managed irrigation years did not affect the sensitivities of VIs to the variations in CWC and \({\overline{EWT}}\). However, the relationships between CWC and VIs were more noticeable in 2014 than in 2013. In contrast, \({\overline{EWT}}\) and VIs were more closely related in 2013 than in 2014. CWC and relative soil water content (RSWC) obviously exhibited a two-dimensional trapezoid space, which illustrated that CWC was determined not only by soil water status but also by crop growth and stage of development. This study demonstrated that nearly half of the variation in CWC explained by spectral information was derived from the variation in leaf area index (LAI).
ZhangF, ZhouG, ChristerN ( 2015). Remote estimation of the fraction of absorbed photosynthetically active radiation for a maize canopy in Northeast China Journal of Plant Ecology, 8, 429-435. DOIURL [本文引用: 3] Aims Accurate remote estimation of the fraction of absorbed photosynthetically active radiation (fAPAR) is essential for the light use efficiency (LUE) models. Currently, one challenge for the LUE models is lack of knowledge about the relationship between fAPAR and the normalized difference vegetation index (NDVI). Few studies have tested this relationship against field measurements and evaluated the accuracy of the remote estimation method. This study aimed to reveal the empirical relationship between NDVI and fAPAR and to improve algorithms for remote estimation of fAPAR. Methods To investigate the method of remote estimation of fAPAR seasonal dynamics, the CASA (Carnegie mes tanford Approach) model and spectral vegetation indices (VIs) were used for in situ measurements of spectral reflectance and fAPAR during the growing season of a maize canopy in Northeast China. Important Findings The results showed that the fAPAR increased rapidly with the day of year during the vegetative stage, it remained relatively stable at the stage of reproduction, and finally decreased slowly during the senescence stage. In addition, fAPARgreen [fAPARgreen = fAPAR 脳 (green LAI/green LAImax)] showed clearer seasonal trends than fAPAR. The NDVI, red-edge NDVI, wide dynamic range vegetation index, red-edge position (REP) and REP with Sentinel-2 bands derived from hyperspectral remote sensing data were all significantly positively related to fAPARgreen during the entire growing season. In a comparison of the predictive performance of VIs for the whole growing season, REP was the most appropriate spectral index, and can be recommended for monitoring seasonal dynamics of fAPAR in a maize canopy.
ZhangF, ZhouG ( 2017). Deriving a light use efficiency estimation algorithm using in situ hyperspectral and eddy covariance measurements for a maize canopy in Northeast China Ecology and Evolution, 7, 4735-4744. DOIURLPMID [本文引用: 1] Abstract We estimated the light use efficiency ( LUE ) via vegetation canopy chlorophyll content ( CCC canopy ) based on in situ measurements of spectral reflectance, biophysical characteristics, ecosystem CO 2 fluxes and micrometeorological factors over a maize canopy in Northeast China. The results showed that among the common chlorophyll-related vegetation indices (VIs), CCC canopy had the most obviously exponential relationships with the red edge position (REP) ( R 2 0002=0002.97, p0002 < 0002 .001) and normalized difference vegetation index (NDVI) ( R 2 0002=0002.91, p0002 < 0002 .001). In a comparison of the indicating performances of NDVI, ratio vegetation index (RVI), wide dynamic range vegetation index (WDRVI), and 2-band enhanced vegetation index (EVI2) when estimating CCC canopy using all of the possible combinations of two separate wavelengths in the range 400-13000002nm, EVI2 [1214, 1259] and EVI2 [726, 1248] were better indicators, with R 2 values of .92 and .90 ( p0002 < 0002 .001). Remotely monitoring LUE through estimating CCC canopy derived from field spectrometry data provided accurate prediction of midday gross primary productivity ( GPP ) in a rainfed maize agro-ecosystem ( R 2 0002=0002.95, p0002 < 0002 .001). This study provides a new paradigm for monitoring vegetation GPP based on the combination of LUE models with plant physiological properties.
ZhaoZ, LiX, YinYB, TangJ, ZhouSB ( 2010). Analysis of spectral features based on water content of desert vegetation Spectroscopy and Spectral Analysis, 30, 2500-2503. [本文引用: 1]
ZhouS, DuursmaRA, MedlynBE, KellyJWG, PrenticeIC ( 2013). How should we model plant responses to drought? An analysis of stomatal and non-stomatal responses to water stress Agricultural and Forest Meteorology, 182- 183, 204-214. DOIURL [本文引用: 2] Models disagree on how to represent effects of drought stress on plant gas exchange. Some models assume drought stress affects the marginal water use efficiency of plants (marginal WUE= / ; i.e. the change in photosynthesis per unit of change in transpiration) whereas others assume drought stress acts directly on photosynthetic capacity. We investigated drought stress in an analysis of results from 22 experimental data sets where photosynthesis, stomatal conductance and predawn leaf water potential were measured at increasing levels of water stress. Our analysis was framed by a recently developed stomatal model that reconciles the empirical and optimal approaches to predicting stomatal conductance. The model has single parameterg1, a decreasing function of marginal WUE. Species differed greatly in their estimatedg1values under moist conditions, and in the rate at whichg1declined with water stress. In some species, particularly the sclerophyll trees,g1remained nearly constant or even increased. Photosynthesis was found almost universally to decrease more than could be explained by the reduction ing1, implying a decline in apparent carboxylation capacity (Vcmax). Species differed in the predawn water potential at which apparentVcmaxdeclined most steeply, and in the steepness of this decline. Principal components analysis revealed a gradient in water relation strategies from trees to herbs. Herbs had higher apparentVcmaxunder moist conditions but trees tended to maintain more open stomata and higher apparentVcmaxunder dry conditions. There was also a gradient from malacophylls to sclerophylls, with sclerophylls having lowerg1values under well-watered conditions and a lower sensitivity of apparentVcmaxto drought. Despite the limited amount of data available for this analysis, it is possible to draw some firm conclusions for modeling: (1) stomatal and non-stomatal limitations to photosynthesis must both be considered for the short-term response to drought and (2) plants adapted to arid climate respond very differently from others. Comparative analysis of three chemometric techniques for the spectroradiometric assessment of canopy chlorophyll content in winter wheat 2 2010
... 一元/多元回归技术被广泛用来估算植被参数和作物产量, 然而利用这些方法比如多元线性回归、逐步回归估算植被生物物理/生物化学特征参数时, 容易产生多重共线性问题(Curran, 1989; Mirzaie et al., 2014).研究表明, 偏最小二乘回归分析(PLSR)、人工神经网络(ANN)和主成分回归分析(PCR)在一定程度上能够减小多重共线性问题的影响(Atzberger et al., 2010; Mirzaie et al., 2014).此外, Mirzaie等(2014)研究揭示出偏最小二乘回归分析对植被含水量的反演精度最高, 主成分回归分析对植被含水量的反演精度最低, 原因在于主成分分析主要侧重于对自变量的解释或归纳, 而偏最小二乘回归分析则增强了自变量与因变量之间的相关关系. ...
... 总体而言, 辐射传输模型虽然具有一定理论基础, 但不可避免地具有模型反演的缺陷(Darvishzadeh et al., 2011; Atzberger et al., 2015), 模型运行所需要的特定参数(比如平均叶角、土壤背景反射率), 尤其在复杂冠层条件下, 往往不易获取.在统计学方法上, 不仅需要建立在大量数据观测以及所获取的数据属性(数量、质量以及数据代表性), 而且依赖于特定的传感器、研究位点和取样条件, 但该方法易于开展(Atzberger et al., 2015), 一直沿用至今, 并有广泛的应用.全波段分析方法在一定程度上克服了多元线性回归、逐步回归的多重共线性问题, 对于植被生物物理参数具有较好的预测能力(Atzberger et al., 2010), 但难以克服过拟合问题(Ren & Zhou, 2014), 而且Mirzaie等(2014)利用遥感植被指数的任意波段组合进行植被含水量遥感估算时也取得优于全波段分析方法的研究结果.综上所述, 各种研究方法各有千秋, 各有侧重, 各有优势, 虽然不乏改进空间, 但它们均在植被含水量高光谱遥感反演的发展进程中发挥着不可或缺的重要作用. ...
Comparative analysis of different retrieval methods for mapping grassland leaf area index using airborne imaging spectroscopy 2 2015
... 总体而言, 辐射传输模型虽然具有一定理论基础, 但不可避免地具有模型反演的缺陷(Darvishzadeh et al., 2011; Atzberger et al., 2015), 模型运行所需要的特定参数(比如平均叶角、土壤背景反射率), 尤其在复杂冠层条件下, 往往不易获取.在统计学方法上, 不仅需要建立在大量数据观测以及所获取的数据属性(数量、质量以及数据代表性), 而且依赖于特定的传感器、研究位点和取样条件, 但该方法易于开展(Atzberger et al., 2015), 一直沿用至今, 并有广泛的应用.全波段分析方法在一定程度上克服了多元线性回归、逐步回归的多重共线性问题, 对于植被生物物理参数具有较好的预测能力(Atzberger et al., 2010), 但难以克服过拟合问题(Ren & Zhou, 2014), 而且Mirzaie等(2014)利用遥感植被指数的任意波段组合进行植被含水量遥感估算时也取得优于全波段分析方法的研究结果.综上所述, 各种研究方法各有千秋, 各有侧重, 各有优势, 虽然不乏改进空间, 但它们均在植被含水量高光谱遥感反演的发展进程中发挥着不可或缺的重要作用. ...
Sensitivity of spectral reflectance to variation in live fuel moisture content at leaf and canopy level 2 2004
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Use of remotely sensed data for fire danger estimation 2 1996
... 活体可燃物湿度(LFMC, %)是指活植物体中叶片水分与干物质的比例, 它是决定火险和火行为模拟的重要可燃物特性(Burgan, 1996).通过公式(3) (Yebra et al., 2013)计算: ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Best hyperspectral indices for tracing leaf water status as determined from leaf dehydration experiments 1 2015
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
A new look at the simplified method for remote sensing of daily evapotranspiration 1 1995
Designing a spectral index to estimate vegetation water content from remote sensing data: Part 1: Theoretical approach 2 2002
... 冠层含水量(CWC, g·m-2)是指单位地表面积植被冠层的含水量(Ceccato et al., 2002), 往往通过单位叶面积水分含量(EWT)与叶面积指数(LAI)的乘积, 或者由叶片生物量鲜质量(mfresh, g·m-2)与生物量干质量(mdry, g·m-2)的差值进行计算(Danson et al., 1992; Clevers et al., 2008): ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Estimation of green grass/herb biomass from airborne hyperspectral imagery using spectral indices and partial least squares regression 1 2007
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
Estimation of fuel moisture content from multi temporal analysis of Landsat Thematic Mapper reflectance data: Applications in fire danger assessment 1 2002
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
Using spectral information from the NIR water absorption features for the retrieval of canopy water content 5 2008
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 冠层含水量(CWC, g·m-2)是指单位地表面积植被冠层的含水量(Ceccato et al., 2002), 往往通过单位叶面积水分含量(EWT)与叶面积指数(LAI)的乘积, 或者由叶片生物量鲜质量(mfresh, g·m-2)与生物量干质量(mdry, g·m-2)的差值进行计算(Danson et al., 1992; Clevers et al., 2008): ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Estimating canopy water content using hyperspectral remote sensing data 3 2010
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
An improved strategy for regression of biophysical variables and Landsat ETM+ data 1 2003
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
Estimation of leaf and canopy water content in poplar plantations by means of hyperspectral indices and inverse modeling 2 2008
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
... 一元/多元回归技术被广泛用来估算植被参数和作物产量, 然而利用这些方法比如多元线性回归、逐步回归估算植被生物物理/生物化学特征参数时, 容易产生多重共线性问题(Curran, 1989; Mirzaie et al., 2014).研究表明, 偏最小二乘回归分析(PLSR)、人工神经网络(ANN)和主成分回归分析(PCR)在一定程度上能够减小多重共线性问题的影响(Atzberger et al., 2010; Mirzaie et al., 2014).此外, Mirzaie等(2014)研究揭示出偏最小二乘回归分析对植被含水量的反演精度最高, 主成分回归分析对植被含水量的反演精度最低, 原因在于主成分分析主要侧重于对自变量的解释或归纳, 而偏最小二乘回归分析则增强了自变量与因变量之间的相关关系. ...
Estimating the foliar biochemical concentration of leaves with reflectance spectrometry: Testing the Kokaly and Clark methodologies 1 2001
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
High spectral resolution data for determining leaf water content 6 1992
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 冠层含水量(CWC, g·m-2)是指单位地表面积植被冠层的含水量(Ceccato et al., 2002), 往往通过单位叶面积水分含量(EWT)与叶面积指数(LAI)的乘积, 或者由叶片生物量鲜质量(mfresh, g·m-2)与生物量干质量(mdry, g·m-2)的差值进行计算(Danson et al., 1992; Clevers et al., 2008): ...
... 叶片等量水厚度(EWT, g·cm-2)通常是指叶片尺度单位叶面积水分含量, 也可以在冠层尺度进行计算(Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990; Danson et al., 1992; Jacquemoud et al., 1996), 如公式(2). ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
... ) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
The spectral response of Buxus sempervirens to different types of environmental stres—A laboratory experiment 2 2012
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
... 指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Detecting leaf- water content in Mediterranean trees using high-resolution spectrometry 1 2014
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
a). Estimation of vegetation LAI from hyperspectral reflectance data: Effects of soil type and plant architecture 1 2008
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
LAI and chlorophyll estimation for a heterogeneous grassland using hyperspectral measurements 2 2008
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
... ; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
Mapping grassland leaf area index with airborne hyperspectral imagery: A comparison study of statistical approaches and inversion of radiative transfer models 2 2011
... 总体而言, 辐射传输模型虽然具有一定理论基础, 但不可避免地具有模型反演的缺陷(Darvishzadeh et al., 2011; Atzberger et al., 2015), 模型运行所需要的特定参数(比如平均叶角、土壤背景反射率), 尤其在复杂冠层条件下, 往往不易获取.在统计学方法上, 不仅需要建立在大量数据观测以及所获取的数据属性(数量、质量以及数据代表性), 而且依赖于特定的传感器、研究位点和取样条件, 但该方法易于开展(Atzberger et al., 2015), 一直沿用至今, 并有广泛的应用.全波段分析方法在一定程度上克服了多元线性回归、逐步回归的多重共线性问题, 对于植被生物物理参数具有较好的预测能力(Atzberger et al., 2010), 但难以克服过拟合问题(Ren & Zhou, 2014), 而且Mirzaie等(2014)利用遥感植被指数的任意波段组合进行植被含水量遥感估算时也取得优于全波段分析方法的研究结果.综上所述, 各种研究方法各有千秋, 各有侧重, 各有优势, 虽然不乏改进空间, 但它们均在植被含水量高光谱遥感反演的发展进程中发挥着不可或缺的重要作用. ...
基于光谱分析与角度斜率指数的植被含水量研究 1 2016
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
基于光谱分析与角度斜率指数的植被含水量研究 1 2016
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
Determining the water status of Satsuma mandarin trees (Citrus unshiu Marcovitch) using spectral indices and by combining hyperspectral and physiological data. 3 2010
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
... ).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
... ).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
NDWI—A normalized difference water index for remote sensing of vegetation liquid water from space 1 1996
A verification of the ‘triangle’ method for obtaining surface soil water content and energy fluxes from remote measurements of the normalized difference vegetation index (NDVI) and surface radiant temperature 1 1997
Measurement of leaf relative water content by infrared reflectance 2 1987
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Detection of changes in leaf water content using near and middle-infrared reflectances 2 1989
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 叶片等量水厚度(EWT, g·cm-2)通常是指叶片尺度单位叶面积水分含量, 也可以在冠层尺度进行计算(Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990; Danson et al., 1992; Jacquemoud et al., 1996), 如公式(2). ...
Non-destructive estimation of water status of intact crop leaves based on spectral reflectance measurements 3 1993
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Spectral response of cotton to suddenly induced water stress 1 1985
Prospect—A model of leaf optical properties spectra 3 1990
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 叶片等量水厚度(EWT, g·cm-2)通常是指叶片尺度单位叶面积水分含量, 也可以在冠层尺度进行计算(Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990; Danson et al., 1992; Jacquemoud et al., 1996), 如公式(2). ...
Estimating leaf biochemistry using the PROSPECT leaf optical properties model 2 1996
... 叶片等量水厚度(EWT, g·cm-2)通常是指叶片尺度单位叶面积水分含量, 也可以在冠层尺度进行计算(Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990; Danson et al., 1992; Jacquemoud et al., 1996), 如公式(2). ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
2 1983
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
Estimation of leaf water status to monitor the risk of forest fires by using remotely sensed data 4 2004
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
... 不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Comparative analysis of different uni- and multi-variate methods for estimation of vegetation water content using hyper-spectral measurements 6 2014
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
... 一元/多元回归技术被广泛用来估算植被参数和作物产量, 然而利用这些方法比如多元线性回归、逐步回归估算植被生物物理/生物化学特征参数时, 容易产生多重共线性问题(Curran, 1989; Mirzaie et al., 2014).研究表明, 偏最小二乘回归分析(PLSR)、人工神经网络(ANN)和主成分回归分析(PCR)在一定程度上能够减小多重共线性问题的影响(Atzberger et al., 2010; Mirzaie et al., 2014).此外, Mirzaie等(2014)研究揭示出偏最小二乘回归分析对植被含水量的反演精度最高, 主成分回归分析对植被含水量的反演精度最低, 原因在于主成分分析主要侧重于对自变量的解释或归纳, 而偏最小二乘回归分析则增强了自变量与因变量之间的相关关系. ...
The reflectance at the 950-970 nm region as an indicator of plant water status 3 1993
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
Cell wall elastivity and Water Index (R970 nm/R900 nm) in wheat under different nitrogen availabilities 2 1996
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
Spectroscopic analysis of seasonal changes in live fuel moisture content and leaf dry mass 1 2014
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
基于纤维素吸收指数(CAI)的内蒙古荒漠草原非绿色生物量估算 1 2012
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
基于纤维素吸收指数(CAI)的内蒙古荒漠草原非绿色生物量估算 1 2012
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
Estimating aboveground green biomass in desert steppe using band depth indices 1 2014
... 总体而言, 辐射传输模型虽然具有一定理论基础, 但不可避免地具有模型反演的缺陷(Darvishzadeh et al., 2011; Atzberger et al., 2015), 模型运行所需要的特定参数(比如平均叶角、土壤背景反射率), 尤其在复杂冠层条件下, 往往不易获取.在统计学方法上, 不仅需要建立在大量数据观测以及所获取的数据属性(数量、质量以及数据代表性), 而且依赖于特定的传感器、研究位点和取样条件, 但该方法易于开展(Atzberger et al., 2015), 一直沿用至今, 并有广泛的应用.全波段分析方法在一定程度上克服了多元线性回归、逐步回归的多重共线性问题, 对于植被生物物理参数具有较好的预测能力(Atzberger et al., 2010), 但难以克服过拟合问题(Ren & Zhou, 2014), 而且Mirzaie等(2014)利用遥感植被指数的任意波段组合进行植被含水量遥感估算时也取得优于全波段分析方法的研究结果.综上所述, 各种研究方法各有千秋, 各有侧重, 各有优势, 虽然不乏改进空间, 但它们均在植被含水量高光谱遥感反演的发展进程中发挥着不可或缺的重要作用. ...
Exploring a V-I-S (vegetation-impervious surface-soil) model for urban ecosystem analysis through remote sensing: Comparative anatomy for citied 1 1995
Forest-BGC, a general model of forest ecosystem processes for regional applications II. Dynamic carbon allocation and nitrogen budgets 1 1991
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
Regional hydrologic and carbon balance responses of forests resulting from potential climate change 1 1991
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
A simple interpretation of the surface temperature/vegetation index space for assessment of surface moisture status 1 2002
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
Using imaging spectroscopy to study ecosystem processes and properties 1 2004
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
Light scattering by leaf layers with application to canopy reflectance modeling: The SAIL model 1 1984
A global review of remote sensing of live fuel moisture content for fire danger assessment: Moving towards operational products 2 2013
... 活体可燃物湿度(LFMC, %)是指活植物体中叶片水分与干物质的比例, 它是决定火险和火行为模拟的重要可燃物特性(Burgan, 1996).通过公式(3) (Yebra et al., 2013)计算: ...
... 植被水分指标的决定因素及其相互关系如图1所示, CWC来源于叶片mfresh和mdry的差值, 而EWT是CWC与LAI的比值, 进而EWT和DMC共同决定LFMC的变异.植被水分指示指标中, 只有EWT直接与水分吸收的辐射密切相关(Yebra et al., 2013). ...
Estimation of leaf water content in cotton by means of hyperspectral indices 6 2013
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
... ; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Leaf and canopy water content estimation in cotton using hyperspectral indices and radiative transfer models 7 2014
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
... , 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Vegetation water content during SMEX04 from ground data and Landsat 5 Thematic Mapper imagery 1 2008
... 植被是陆地生态系统的重要组成部分, 植被冠层中水分含量为40%-80% (沈艳等, 2005).植被含水量(vegetation water content, VWC)是植被干旱胁迫状态的重要指示指标, 常见植被水分指标有冠层含水量(canopy water content, CWC) (Danson et al., 1992; Clevers et al., 2008)、叶片等量水厚度(equivalent water thickness, EWT) (Hunt Jr & Rock, 1989; Jacquemoud & Baret, 1990)、活体可燃物湿度(live fuel moisture content, LFMC) (Bowyer & Danson, 2004)以及相对含水量(relative water content, RWC) (Hunt Jr et al., 1987; Inoue et al., 1993).植物水分是影响绿色植物光合作用和生物量的主要因素, 许多关键生物地球化学循环过程, 包括光合作用、蒸发散和净初级生产力均直接与其密切相关(Running & Gower, 1991; Running & Nemani, 1991; de Jong et al., 2014).植物水分在植被功能、植被与大气之间的水分交换和能量传输, 干旱以及火险评估中发挥着重要作用(Pe?uelas et al., 1993, 1996; Mirzaie et al., 2014), 其深入研究对于准确监测与诊断植被环境胁迫程度(Ustin et al., 2004)、自然火潜在发生(Chuvieco et al., 2002)以及土壤水分有效获取(Yilmaz et al., 2008)等具有重要研究意义. ...
干旱指标的理论分析与研究展望 1 2004
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
干旱指标的理论分析与研究展望 1 2004
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
Estimating canopy characteristics of Inner Mongolia’s grasslands from field spectrometry 2014
Estimation of canopy water content by means of hyperspectral indices based on drought stress gradient experiments of maize in the North Plain China 2 2015
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
Remote estimation of the fraction of absorbed photosynthetically active radiation for a maize canopy in Northeast China 3 2015
... 当前, 植被含水量高光谱遥感估算研究在国内外备受关注, 其准确定量遥感反演不仅对于农林和水文研究具有重要意义, 而且对于植被干旱评估具有不可忽视的作用(邓兵等, 2016).植被含水量准确定量遥感估算有助于: (1)检测植被生理状态, 水分胁迫对植物长势和产量的影响比任何其他胁迫都要大得多, 准确地监测或诊断叶片/冠层含水量可以及时反映植物生理状况(Kramer, 1983; Pe?uelas et al., 1993; 张佳华等, 2007; Yi et al., 2013); (2)植被干旱胁迫程度的实时监测与准确评估(袁文平和周广胜, 2004; 李柏贞和周广胜, 2014; Mirzaie et al., 2014; Cao et al., 2015; Zhang & Zhou, 2015); (3)预测森林、草原火险发生, 而且植被含水量指标也是燃烧效率和火险预测的重要参数(Maki et al., 2004); (4)农业灌溉决策与产量评估(唐延林和黄敬峰, 2001; 张佳华等, 2010; Yi et al., 2013, 2014).因此, 为更好地开展植被干旱胁迫遥感监测的方法与诊断模型研究, 本文将综述国内外广泛使用的各类植被水分指标及其遥感估算方法, 评述植被水分高光谱遥感估算各类方法的优缺点, 并探讨目前存在的问题以及未来拟开展的研究发展方向, 以期为我国植被干旱胁迫的高光谱遥感监测、预警与评估提供重要的科学依据. ...
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
Deriving a light use efficiency estimation algorithm using in situ hyperspectral and eddy covariance measurements for a maize canopy in Northeast China 1 2017
... 遥感技术是一种快捷、非破坏、多尺度探测植被生物物理(Cohen et al., 2003; Cho et al., 2007; Darvishzadeh et al., 2008a, 2008b; 任鸿瑞等, 2012; Zhang et al., 2014, 2015; Zhang & Zhou, 2017)与生物化学(Curran et al., 2001; Darvishzadeh et al., 2008b; 张峰和周广胜, 2014)特征的重要研究手段.近年来, 高光谱遥感技术相对于传统的宽波段遥感, 光谱分辨率大大提高, 能够详细记录各波段反射率值, 有效提高了植被含水量遥感反演精度, 广泛应用于作物干旱、森林和草原火灾、土地覆盖变化以及农作物产量监测(Zhang et al., 2010). ...
How should we model plant responses to drought? An analysis of stomatal and non-stomatal responses to water stress 2 2013
... 当前, 对于植物本身可以测定的用来指示植物水分状况的常见指标主要有: 气孔导度(Zhou et al., 2013)、叶水势(Dzikiti et al., 2010; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
... ; Zhou et al., 2013)、冠层含水量(CWC) (Danson et al., 1992; Ceccato et al., 2002; Clevers et al., 2008, 2010; Zhang & Zhou, 2015)、叶片等量水厚度(EWT) (Danson et al., 1992; Jacquemoud et al., 1996)、活体可燃物湿度(LFMC) (Burgan, 1996; Yi et al., 2014)以及相对含水量(RWC) (Hunt Jr et al., 1987; Inoue et al., 1993; Maki et al., 2004).叶片含水量被广泛地认为是干旱胁迫的有效指示指标(Dzikiti et al., 2010; de Jong et al., 2012).关于叶水势, 研究表明与午间叶水势相比, 午间茎水势是更好的干旱监测指标, 即午间叶水势大的变异性并不意味着它是干旱的有效监测指标(Dzikiti et al., 2010).LFMC不仅受叶片湿度状态的影响, 而且与干物质的季节变化有关, 代表了供燃烧的可燃物量的大小, 它是火险评估中用来指示植被水分状态的最好指标(Maki et al., 2004), 但研究认为遥感信息对于LFMC的反演能力远不及EWT (Yi et al., 2013, 2014).RWC是叶片含水量与叶片完全膨胀时最大含水量之比, 常被用来评估植物的水分状况, 人们已经利用光谱信息进行该指标的遥感估算(Qi et al., 2014).EWT指示单位叶面积的含水量, 更多地与能量吸收有关, 其快速降低被认为是干旱胁迫的早期指示指标(de Jong et al., 2012).此外, CWC广泛应用于植被水分状况的遥感监测, 它不仅与植被水分状况有关, 而且与植被的生长发育状况密切相关(Zhang & Zhou, 2015), CWC的遥感反演并不需要区分LAI和水分信息对光谱反射率的贡献(Bowyer & Danson, 2004; Colombo et al., 2008).因此, 高光谱遥感技术可实现对植被水分状况和植被干旱胁迫的实时监测, 但是究竟哪一个植被水分指标更适合于植被水分胁迫过程的遥感监测还有待进一步深入研究. ...
,1,2,*
新窗口打开|下载原图ZIP|生成PPT
