摘要
摘要:耕地土壤碳库是全球碳库中最为活跃的部分，其变化对全球气候变化产生重要影响。目前对耕地土壤有机碳估算多采用中、小系列比例尺的土壤数据库，较少结合遥感影像与大比例尺土壤数据库进行估算。基于此，本研究采用Landsat遥感影像和1:50 000高精度土壤数据库，以福建省福州市为例，基于遥感与碳循环过程模型对1987年和2016年耕地土壤有机碳动态变化进行研究。结果表明，利用Landsat影像反演得到的耕地土壤基础呼吸与土壤有机碳相关性强，建立的1987年和2016年模型R²分别为0.637和0.752。研究期间，全市耕地土壤有机碳密度从东部沿海向西部内陆地区递增，整体发挥着“碳汇”作用，有机碳密度和储量分别增加0.20 kg·m^-2和2.946×10⁵ t。从不同土壤类型比较得出，黄壤、红壤和水稻土是“碳汇”，有机碳密度分别增加0.70 kg·m^-2、0.40 kg·m^-2和0.19 kg·m^-2；其他土类为“碳源”，其中，水稻土碳储量最大，两期在全市总碳储量中占比均超过90%。从不同行政区比较得出，仓山区、长乐区、马尾区和连江县为“碳源区”，其他地区为“碳汇区”，其中，仓山区碳储量一直为全市最低，两期占比均不足0.5%，而福清市则一直居于全市首位，占比均高于20%。总体而言，福州市耕地土壤有机碳30年间空间动态变化显著，在不同土类和行政区间存在差异，今后应根据不同耕地土壤类型和行政区的有机碳情况有针对性进行耕地管理。
关键词:耕地/
土壤有机碳密度/
土壤有机碳储量/
遥感反演/
碳循环过程模型/
土壤基础呼吸/
福州市
Abstract:Carbon pools in farmlands are critical drivers of change in global carbon stock and a small change in these pools could have a huge influence on CO₂ concentration in the atmosphere, causing global greenhouse condition. Though medium and small scale soil databases have often been used in estimating soil organic carbon (SOC) in farmlands, remote sensing image and large-scale soil database have rarely been used. In this study, we combined remote sensing and carbon cycle model to estimate SOC in farmland of Fuzhou City (in subtropical China) using Landsat TM and Landsat 8 OLI remote sensing images plus 1:50 000 high-resolution soil database. In the study area, SOC in farmlands was calculated for 1987 and 2016. The purpose of the study was to determine whether the study area was source or sink of SOC and the dynamics of SOC pool in the region. The results showed that:1) there was a strong linear relationship between soil basal respiration and soil organic carbon density (SOCD) in farmlands in Fuzhou City. The determinant coefficient R² was 0.637 for 1987 and 0.752 for 2016. 2) For the study period, SOCD in farmlands increased from eastern coastal area to western inland area. In general, SOCD and soil organic carbon storage (SOCS) increased by 0.20 kg·m^-2 in the eastern coastal area and 2.946×10⁵ kg·m^-2 in western inland area, indicating that farmlands in Fuzhou City served as a weak "carbon sink" in the past 30 years. 3) In terms of soil type, yellow earth, red earth and paddy soil contributed the largest to "carbon sink" across the soil groups, with respective SOCD increases of 0.70 kg·m^-2, 0.40 kg·m^-2 and 0.19 kg·m^-2. Fluvo-aquic soil, latosolic red soil, aeolian soil, coastal solonchak and purplish soil were the biggest contributors to "carbon source" across the soil group. Comparison of SOCS of different soil types in 1987 with those in 2016 showed that SOCS was highest in paddy soil, accounting for over 90% of the total carbon storage in Fuzhou City. 4) In terms of administrative region, Cangshan District, Changle District, Mawei District and Lianjiang County were "carbon source" areas. Then Minhou County, Minqing County, Fuqing City, Jin'an District, Yongtai County and Luoyuan County were "carbon sink" areas. The lowest SOCS was in Cangshan District in Fuzhou City, with less than 0.5% of total SOCS. Fuqing City always ranked the highest in Fuzhou City, accounting for over 20.0% of the total SOCS. In general, the spatial dynamics of SOCD in farmlands in Fuzhou City during the 30-year period were significant. Additionally, there were differences in different soil types and administrative regions in terms of SOCD. In future, it was beneficial to conduct farmland management based on soil type in different farmlands and SOC in the administrative regions.
Key words:Farmland/
Soil organic carbon density/
Soil organic carbon storage/
Remote sensing inversion/
Carbon process-based model/
Soil basal respiration/
Fuzhou City



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