中文摘要：

以陕西省为例,运用1999～2008年全省气候资料、农用地面积数据、主要农作物产品产量数据以及2006年11个地级市农用地面积数据,从土地利用数量、构及程度三方面,采用生态学理论与方法研究1999～2008年全省的农用地利用动态变化状况及不同农用地类型的植被固定CO〈,2〉物质量的时空变化情况,得出结论：（1）1999-2008年陕西省的植被固定CO〈,2〉总量随降水量的显著变化而出现明显的差异变化,但大体呈增加的趋势;（2）林地和园地在CO〈,2〉固定过程中占据优势,是农用地植被固定CO〈,2〉最重要贡献者.年平均降水量对园地和林地固定CO〈,2〉的物质量影响程度要远大于其面积变化的影响.同时国家和区域的经济政策及调整对植被固定CO〈,2〉＇物质量有显著影响并存在空间差异;（3）2006年陕西省植被固定CO〈,2〉的量有显著的区域差异,呈南北高、中间低的总特征;（4）一个地区农用地在土地利用结构中所占比例越大则植被固定CO〈,2〉量越高.林地占农用地面积比例越大则植被固定CO〈,2〉量越高.

英文摘要：

Taking Shaanxi Province for example,based on the climate data,the agricultural land area date,the main crops＇ production from 1989～2008 and the statistic data of agricultural land area in Shaanxi in 2006,the paper analyzes the dynamic change of land-use and the spatial-temporal changes and differences of CO2 fixed by different kinds of agricultural vegetation in Shaanxi from three aspects： the number,the structure,and the extent of land-use.And the conclusions were drawn as follows：（1） The total CO2 fixed by different agricultural vegetation had obvious changes with the difference of the precipitation and was increasing in Shaanxi from 1989～2008;（2） Woodland and orchard dominated CO2 fixed by different kinds of agricultural vegetation and were the most important contributors.The annual average temperature had more influence on quantities of CO2 fixed by woodland and orchard than the influence from its area change.Quantities of CO2 fixed was remarkably influenced by the national and regional economic policy and adjustment,and had obviously differences in space;（3） The quantities of CO2 fixed by agricultural vegetation in Shaanxi were different among regions in 2006,and its total characteristic is that the north and south was high,while the middle was low;（4） The bigger the proportion of agricultural land,the higher the quantities of CO2 fixed.The bigger the proportion of woodland,the higher the quantities of CO2 fixed.