亚热带常绿阔叶林植被净初级生产力时空特征
Spatial-temporal Characteristics of NPP in Subtropical Evergreen Broad-leaved Forests

植被净初级生产力(NPP)是森林生态系统碳循环过程的关键参数，在研究减缓全球气候变化中起着重要的作用。中国的亚热带常绿阔叶林是世界常绿阔叶林的重要组成部分，研究该区域植被净初级生产力的时空特征对了解该地区植被生长状况和CO2固定能力等方面有着重要的意义。基于中国科学院资源环境科学数据中心的NPP数据，应用核密度估计、隶属函数等方法分析了亚热带常绿阔叶林区域植被净初级生产力2001-2010年时空分布特征。结果表明，亚热带常绿阔叶林区NPP在时间变化上无显著增减趋势，各年份NPP都主要集中在300~400 gC？m-2？a-1和700~1 000 gC？m-2？a-1，且随时间序列呈现波动变化，其年均值在600~700 gC？m-2？a-1；在空间分布上，湿润地区NPP呈东南向西北逐渐降低的空间分布特征，半湿润地区NPP则呈西高东低的特征。此外，2001-2010年亚热带湿润地区西部NPP变差系数高于东部，半湿润地区的北部NPP变差系数高于南部。通过NPP与其变差系数值，得出其NPP隶属度空间分布，结果显示隶属度呈东南沿海向内陆递增趋势，可以看出东南部NPP值高，变异系数低，CO2固定能力高，抗干扰能力强，生态风险低；而西部部分地区NPP值低，变异系数高，易受外界干扰，生态风险高。
Net primary productivity (NPP) plays a critical role in forest carbon cycle and mitigation of climate change.China’s evergreen broad-leaved forest is the main part of the world’s.By studying on the spatial-temporal characteristics of vegetation net primary productivity,it will have important significance to understand the growth condition of vegetation and CO2 fixation ability in this region.The NPP data rooted in the Resources and Environment Science Data Center,Chinese Academy of Sciences.Based on kernel density estimation,membership function and other research software and methods,the NPP data were utilized to analyze the spatial-temporal characteristics of vegetation net primary productivity in subtropical evergreen broad-leaved forest from 2001 to 2010.The results showed that NPP in subtropical evergreen broad-leaved forest regions had no significant change.The NPP fastened on 300-400 gC？m-2？a-1 and 700-1 000 gC？m-2？a-1,and it presented the fluctuation changes in study region.Its annual mean was fluctuated between 600 and 700 gC？m-2？a-1.There had a gradually decreasing trend of NPP from southeast to northwest in subtropical humid region,while the same trend occurred from west to east in subtropical semi-humid region.In addition,the variation coefficient of NPP was higher in west than east in the subtropical humid region,but higher in north than south in the subtropical semi-humid region.Through NPP and its variation coefficient,this paper obtained the spatial distribution of NPP membership degree,and based on the membership degree,it showed the increasing trend from the southeast coast to the inland.According above results,the article concluded that there had the greatest carbon sequestration,higher resisting disturbance capacity and low ecosystem risk in southeastern,but the opposite results in southwestern in subtropical evergreen broad-leaved forest region