鄱阳湖农业区多熟种植时空格局特征遥感分析

Spatio-temporal distribution of multiple cropping systems in the Poyang Lake region

农业土地利用活动是人类作用于地球系统最为直接的扰动因素,其变化会因改变生态系统过程与格局以及生态系统资源有效性而对生态系统功能在局地到全球尺度都产生重要的影响。中国南方普遍实施的多熟种植制度是高强度土地利用的重要特征之一,在中国传统的三熟农业区之一——江西省鄱阳湖区域,以农户为管理单元的农业种植制度由于受到洪水风险、经济效益及农业政策的调节,其时空格局动态也因此更加复杂。以分布在鄱阳湖平原的农田为研究区,结合多时相MODIS影像表达的作物生长规律和农业物候观测记录,检测并分析农业多熟种植的时空格局特征。研究结果表明空间分辨率500m、8d合成的MODIS/EVI时间序列数据能够定量表达出农业种植的多熟制特征,可以应用于区域农业多熟种植制度时空分析,研究区种植制度时空格局的形成是农户对气候、社会经济及粮食安全状况响应及适应的结果。在空间和时间上清晰地认识农业多熟种植的特征,将会对掌握高强度土地利用的过程和特点,模拟与评估土地利用对粮食安全及生态环境安全的影响有重要的意义。

Agricultural land use and management is one of the most direct means by which humans impact the earth system, with significant negative environmental effects at local to global scales due to altered ecosystem processes, patterns and resource use. Multiple cropping is of particular interest because agricultural intensification has increased pressure on water resources, ecosystems, and biodiversity due to increased water withdrawals for irrigation and higher energy inputs due to mechanization and the production of chemical fertilizer. The Poyang Lake region is one of the most intensified agricultural regions in southern China, and the spatial and temporal pattern of cropping systems is determined not only by climate and water availability. Population pressure, social and economic conditions and policies, flood risks, and individual farmers＇management decisions also have profound impacts. Therefore, the spatial pattern and temporal process of multiple cropping is quite complex. In this paper, we combined agro-meteorological observation data and MODIS data with a resolution of 500m at 8-day intervals to explore a novel and robust method to examine spatial and temporal dynamics of multiple cropping and crop calendar using a MODIS/EVI time series curve. The results indicate that a cropping intensity algorithm based on this data is potentially applicable for monitoring agricultural intensification. Spatial and temporal variability of multiple cropping may be the result of farmers＇ dynamic adaptation to local climate, socio-economic conditions, and food security. An explicit spatial and temporal analysis of the complex dynamics of multiple cropping in the context of coupled human and natural systems is necessary for modeling and evaluating the impacts of human activity on global environmental change and food security.