Space-Time Characteristics of Net Primary Productivity of Farmland Vegetation in Jingzhou City

Based on MODIS data and light energy utilization rate model to estimate NPP data, supplemented by climate and land use data, by using the trend analysis, GIS analysis and statistical analysis method, we here discusses the space-time characteristics of vegetation net primary productivity of farmland in Jingzhou City for 2000-2015. The results show that:(1) the annual average NPP of farmland in Jingzhou decreased slightly, but the overall trend was stable during the period from 2000 to 2015. The total amount of NPP increased in 2000-2005, the volatility decreased in 2005-2009 while increased in 2009-2016; (2) in terms of spatial distribution, there are spatial and temporal heterogeneity in farmland NPP of Jingzhou city for 2000-2015. The annual maximum NPP was in Jiangling County, while the lowest area was in Shashi District and Honghu City; (3) there was no significant change in the NPP being about 64.32% of the Jingzhou farmland, while the areas with significant rise and fall were of 3.82% and 31.86% of the farmland, respectively. The areas with significant increase of farmland NPP are mainly distributed in Jiangling County, Shashi district, Jianli County and scattered in Honghu City and Songzi City. The areas with significant decrease of farmland NPP are mainly distributed in in Songzi City, public security county and Shishou City, the southwest of the Jingzhou City, Honghu City; in the northeast, named as Honghu City and in the northwest, i.e. Jingzhou District.