中文摘要：

植被净初级生产力及其对气候变化的响应研究是全球变化的核心内容之一。在利用内蒙古典型草原连续13年的地上生物量资料对基于遥感信息的生态系统碳循环过程CASA（Camegie-Ames-Stanford Approach）模型验证的基础上，分析了内蒙古典型草原1982-2002年植被净初级生产力（Net primary productivity，NPP）的时间变异及其影响因子。结果表明：1）1982～2002年21年间内蒙古典型草原的平均年NPP为290．23 g C·m^-2．a^-1，变化范围为145．80～502．84 g C·m^-2·a^-1；2）内蒙古典型草原NPP呈增加趋势，但没有达到显著性水平，其中1982～1999年的18年间NPP呈现非常显著的增加趋势（P〈0．01），NPP增加的直接原因是由于生长旺季生长本身增强所致；3）内蒙古典型草原NPP与年降水量呈极显著的相关关系，年降水量显著影响NPP的变异，而NPP与年均温无显著相关关系。

英文摘要：

Aims Vegetation net primary productivity （NPP） and its responses to global change have been focuses of global change research. Accurately estimating the spatial patterns and temporal dynamics of net primary productivity （NPP） of terrestrial ecosystems is of great interest to human society and is necessary for understanding the carbon cycle of the terrestrial biosphere. But only a few evidences in various biomes are available on the performance of global models of terrestrial net primary productivity （NPP） at ecosystem level. Methods Vegetation net primary productivity （NPP） derived from a carbon model （Carnegie-Ames-Stanford Approach, CASA） and its inter-annual change at ecosystem level in Inner Mongolian typical steppe, China, are investigated in this study using 1982-2002 time series data sets of normalized difference vegetation index （NDVI） at 8 km spatial resolution and paired ground-based information on vegetation, climate, soil, and solar radiation, after CASA model is validated by the aboveground biomass of 13 years＇ continuous observation. Important Findings Results show that 21-year averaged annual NPP is 290.23 g C·m^-2·a^-1, ranging between 145.80 g C·m^-2·a^-1 and 502.84 g C·m^-2·a^-1. From 1982 to 2002, annual NPP shows a slightly increasing trend, while from 1982 to 1999 a significant increase （p〈0.01） is observed, and the increased NPP is mainly due to the increases of the amplitude of the NPP annual cycle. Annual precipitation significantly affects the variation of NPP, and there is no significant positive correlation between NPP and annual mean temperature.