气候和土地利用变化对北方农牧交错带植被NPP变化的影响

Effects of Climate and Land Use Change on the Changes of NPP in the Farming-Pastoral Ecotone of Northern China

基于1986年、2000年中国北方农牧交错带的遥感影像、气象和土地利用数据,利用光能利用率模型分析了北方农牧交错带1986年～2000年植被净初级生产力(NPP)的时空变化,并分析了气候和土地利用变化对NPP变化的影响。结果显示:①1986年～2000年,研究区植被NPP下降了21.7TgC,单位面积NPP下降了35gC(/m2·a);②NPP>400gC(/m2·a)的区域明显缩减,NPP<400gC(/m2·a)的区域则迅速扩张;③NPP升高区位于华北段的西部和西北段的南部,其它地段NPP明显降低;④NPP变化同降水、干燥度指数变化成正相关,同温度变化成负相关;⑤不同土地利用类型的植被NPP变化程度各异。

Effects The influences of global change on terrestrial ecosystems will result in the responses on change of the types, quantity and quality of vegetation. Vegetation net primary productivity （NPP）is defined as the accumulative amount of organic matters, which is a key component of the terrestrial carbon cycle, per unit area and time, which is a key component of the terrestrial carbon cycle. International Geographical and Biological Plan （IGBP）, Global Change and Terrestrial Ecosystems （GCTE）and Kyoto Protocol all take it as their key research field. Model simulation is commonly used to estimate regional and global NPP, and a number of NPP models have been developed in recent years as research issues related relating to food security and biotic response to global climate change. Light utilization efficiency model based on remote sensing is an absolutely brand new method for NPP estimation in recent years. Remote sensing can provide broad view quickly, timely and multi-temporally, which makesing it an attractive and powerful tool for studying ecosystem primary productivity, at on scales ranging from globe global to regional. Study of changes of NPP changes and the its relationship with climate change and land use change are significant in the farming-pastoral ecotones of Northern northern China, a region which is sensitive to global change. Based on the Advanced Very High Resolution Radiometer （AVHRR） data set, the meteorological data and the land use data of the study area in from 1986 and to 2000, this paper estimates estimated the spatiotemporal changes of NPP in the farming-pastoral ecotones of northern China by using the light utilization efficiency model, and analyzes the effects influences of climate change and land use change on the changes of NPP. The main results showed that： 1 ）The total value of NPP decreased by 21.7 TgC, and the per-pixel value of NPP decreases decreased by 35 gC/（m^2·a）in the farming-pastoral ecotone of Northern northern China from 1986 to 2000;2 ）The area of NPP 〉 400 gC/（m^2·a）was increasing increased obviously, but while the area of NPP 〈 400 gC/（m^2·a）lowered has a sharply decrease from 1986 to 2000; 3 ） The NPP in the western part of north section and the southern part of northwest section rose had obviouslyremarkably been increased, but decreased dropped in the other sections in the farming-pastoral ecotone of northern China; 4）The changes of NPP were in direct proportion to the changes of precipitation as well as aridity index; however, they were in inverse proportion to temperature changes ; 5） The extent of NPP changes was different in different land use types , the NPP of farmland, forestland, grassland and unused land all decreased from 1986 to 2000, but the extent of NPP changes was different in various land use types. Thus, this study will can benefit the process study ofresearch on terrestrial ecosystem changes, and explain the relationship between NPP changes and climate and land use change, and i. Itt would also provides some useful spatial information and theories for the present ecological rehabilitation and some reliable strategies for land use policy in the farming-pastoral ecotone of Northern northern China.