2001-2014年中国植被净初级生产力时空变化及其与气象因素的关系

植被净初级生产力（NPP）是表征植被活动的关键变量，对于评估生态系统承载力，理解陆地生态系统碳循环有着重要意义。以全球陆表特征数据集（GLASS）为基础，对2001-2014年中国植被NPP进行了估算。在此基础上，利用一元线性回归、经验正交分解（EOF）分析了我国植被NPP时空变化，利用逐象元相关性分析、奇异值分解（SVD）两种方法分析了我国植被NPP与温度、降雨量的相关性。结果表明：（1）我国植被NPP空间上基本呈由东南向西北递减的分布趋势，主要是由于植被分布和气候条件决定的。研究期间我国植被NPP呈波动增加趋势，总量在3.02-3.49PgC/a之间，平均约为3.25 PgC/a。（2）一元线性回归与EOF分析结果较为一致，表明我国长江中下游、华北平原和东北长白山地区NPP呈减少趋势，而青藏高原、西北、内蒙古中部及东南沿海地区NPP呈增加趋势。（3） NPP与气象要素逐象元相关性分析表明，长白山、青藏高原及南方地区NPP与温度呈正相关，内蒙东部和西北地区NPP与降雨量呈正相关，东北、长江下游地区NPP与降雨量呈负相关。SVD分析结果与逐象元分析结果基本一致表明，NPP与温度、降雨量均存在明显相关性，长白山、内蒙古、青藏高原地区NPP与温度正相关，西北、内蒙中部地区NPP与降雨量呈正相关，长江下游、东北地区NPP与降雨量呈负相关。

Analysis of spatial and temporal variation of net primary productivity and climate controls in China from 2001 to 2014

Net primary productivity (NPP) is a key variable in characterizing vegetation activity.NPP also plays an important role in evaluating ecosystem carrying capacity and understanding terrestrial ecosystem carbon cycle.The present study estimated the NPP in China from 2001 to 2014 based on the GLASS remote sensing dataset.We also analyzed the spatial and temporal variation of vegetation NPP in China with linear regression and Empirical Orthogonal Function (EOF) algorithms.By using correlation analysis and Singular Value Decomposition (SVD) method,the relationship between NPP and temperature and the relationship between NPP and precipitation were obtained,respectively.The results showed that (1) NPP in China revealed a decreasing pattern from southeast to northwest due to the spatial variability of vegetation and climatic characteristics.NPP also had a fluctuating increase trend during our study period with values ranging between 3.02 and 3.49 PgC/a.The average value was approximately 3.25 PgC/a.(2) The linear regression and EOF results are consistent.Both results indicated that NPP presented a decreasing tendency in the lower Yangtze region,North China Plain,and Changbai mountain area.In the Qinghai-Tibetan Plateau,northwest,central Inner Mongolia,and southeast coastal areas of China,NPP showed an increasing tendency.(3) The correlation analysis between NPP and meteorological elements indicated that NPP was positively correlated with temperature in the Changbai mountain area,Qinghai-Tibet Plateau,and southern area.NPP was also positively correlated with precipitation in the eastern Inner Mongolia and northwestern region.However,in the Northeast,Yangtze River,and east of the Qinghai-Tibetan Plateau area,NPP was negatively correlated with precipitation.The SVD results were consistent with the results of correlation analysis.We found significant correlations between NPP and temperature and precipitation.NPP was positively correlated with temperature in the Changbai mountain area,Inner Mongolia,and Qinghai-Tibet Plateau area.NPP was also positively correlated with precipitation in the northwest and central Inner Mongolia,whereas it was negatively correlated with precipitation in the lower Yangtze River and northeastern area.