摘要:种植指数是反映耕地利用强度的基础性指标，明确其空间格局、时间演变是合理制定农业决策的基础。本文以四川省2000-2016年MODIS-NDVI长时间序列数据为数据源，通过提取耕地NDVI时序曲线峰值频数，进而提取四川省2000-2016年耕地种植指数，分析其时空格局及演变，并结合积温-降水模型对区域耕地潜力种植指数分布进行了分析，为明确四川省耕地种植指数时空特征及演变和引导耕地合理集约利用提供科学依据。结果显示：研究时段内，一年1熟一直是四川省主要的熟制制度，其面积占耕地面积比达78.05%，主要分布在川西北高原区、川东北和川南的低山丘陵区以及攀西河谷区；一年2熟/3熟制主要分布在成都市及其周边地区，空间分布上呈现由成都市及其周边地区向四周下降的态势。可提升潜力种植指数（PMCIp）方面，省内89.7%的耕地仍具有较高的可提升潜力；成都市及其周边地区可提升潜力较低（PMCIp < 50%），且实际种植指数年际变化剧烈（标准差>60%）；川东北和川南地区可提升潜力种植指数在50%以上，面积占耕地面积比达65.6%，是未来耕地种植潜力挖掘的理想区域；川西北高原区、攀西河谷区和川东北大巴山中山区为过度耕作的主要分布区（PMCIp < 0），面积占耕地面积10.3%，是未来农业生态退耕的重点区域。本文结合农作物节律性，利用长时间序列的遥感数据反演，实现对区域耕地种植指数的动态监测，并分析区域耕地种植指数的潜力及可提升潜力的空间格局，为区域农业政策制定提供有益参考。
关键词:四川省/
耕地复种/
种植指数/
潜力种植指数/
MODIS-NDVI/
积温-降水模型
Abstract:Cropping index is one of the basic indexes used to measure use intensity, space-time distribution and changes of farmlands at regional scale, which is essential for basis agricultural decision-making. To investigate cropping indexes, the related changes and potential cropping indexes of farmlands in Sichuan Province, a long-term (2000-2016) series of MODIS-NDVI remote sensing data products were used to reconstruct NDVI time-series curve using Asymmetric Gauss Fitting Function (AGFF). The peak frequencies of the NDVI time-series curves were used for determining the spatial distributions and temporal changes of annual cropping indexes by using the second order difference method. Then the spatial pattern of potential and promotable potential cropping indexes of farmland in Sichuan Province were simulated using the temperature-rainfall model, meteorological data and land-use maps to refine farmland dynamics in the region. The aim of the study was to provide scientifically-drive recommendations to local governments on the regulation of intensive development of farmlands in the study area. The results showed that single cropping pattern, which made up 78.05% of cultivated land, was the main cropping system in Sichuan Province for the period 2000-2016. This mainly distributed in the Northwest Sichuan Plateau region, Northeast Sichuan, Southwest Sichuan Hilly area and Panxi Valley region. The double cropping system mainly distributed in Chengdu region and the surroundings. Overall, the spatial distribution of cropping index (MCI) in Sichuan Province decreased in trend from Chengdu and the surroundings to other regions. According to the promotable and potential cropping indexes, Sichuan Province had 89.7% of cultivated land with higher promotable potential in multiple cropping. Chengdu and the surroundings had lower promotable potential cropping index (PMCIp < 50%) and higher inter-annual fluctuation (standard deviation of cropping index > 60%) than other regions in Sichuan Province. Cultivated land in the northeastern and southern areas of Sichuan (which accounted for 65.6% of the total area of Sichuan), was higher in promotable potential cropping index (PMCIp ≥ 50%) and less inter-annual fluctuation compared with Chengdu and the surroundings. There was the likelihood for this to become the best suitable land with the highest cropping index in Sichuan Province. Accounting for 10.3% of cultivated land area of Sichuan in the northwest and northeast mountainous areas (with negative promotable cropping index) formed the main region of agricultural over-development in the study area. There was therefore the need to classify these farmlands into ecological restoration areas. The cropping indexes extracted by integrating the phenology of crops and long-term series of remote sensing data were significantly correlated with the statistics values in Sichuan, indicating the method was applicable in evaluation of cropping index in provincial scale. The result was beneficial reference to policy decision of regional planting structure.
Key words:Sichuan Province/
Multiple cropping of farmland/
Cropping index/
Potential cropping index/
MODIS-NDVI/
Temperature-rainfall model
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