1996～2015年云贵川草地生态系统生产力的时空格局

云贵川草地是中国草地的重要组成部分，在我国生态文明建设和响应全球气候变化中具有重要的地位，分析其净初级生产力（NPP）变化格局具有重要意义。利用研究区的AVHRR、MODIS遥感影像等数据及周边地区的气象资料，结合改进的CASA模型，对云贵川地区草地1996～2015年20 a间的NPP及草地植被相关生态特征进行估算，并对其时空特征及影响因素进行分析。结果表明：（1）20 a间云贵川草地NDVI值变化规律性明显，97.18%的草地面积年平均NDVImax呈现增加趋势。（2）20 a间云贵川草地NPP总体上呈现出“西北低、西南高、东部居中”的空间格局，年均NPP值为420.85 gC·m-2。 （3）时间格局上，20 a间整个云贵川区域逐年平均NPP值虽然有一定的波动性，但仍以7.2322 gC·m-2·a-1的速率在增加。20 a间夏季NPP平均值最高，为160.25 gC·m-2；春季次之，NPP平均值为 109.10 gC·m-2；秋季与春季相比，NPP值稍低，为106.10 gC·m-2；冬季最低，为54.03 gC·m-2。

RESEARCH ON SPATIO-TEMPORAL VARIATION OF GRASSLAND ECOSYSTEM PRODUCTIVITY IN YUNNAN-GUIZHOU-SICHUAN PROVINCES FROM 1996 TO 2015

The grassland of Yunnan-Guizhou-Sichuan Province serves as an important part of grassland in China,which plays an important role in the construction of ecological civilization and global climatechange.It is of great significance to analyze the change of net primary productivity (NPP) of grassland.This study calculated the NPP of grassland using the improved CASA model,and analyzed spatio-temporal characteristics and influencing factors of grassland ecosystem productivity in Yunnan-Guizhou-Sichuan from 1996 to 2015 based on the remote-sensing image data of AVHRR and MODIS,and the meteorological data of the surrounding areas.The results showed that:(1) The NDVI values of grassland in Yunnan,Guizhou and Sichuan Province obviously showed a regular pattern during the past 20 years,and the annual average value of NDVImax showed an increasing trend in 97.18％ of the grassland area.(2) The NPP of Yunnan-Guizhou-Sichuan grassland showed a spatial pattern of ‘ low value in the northwest,high value in the southwest and medium value in the east'.The annual average NPP was 420.85 gC · m-2 in the past 20 years.(3) The annual average NPP value of Yunnan-Guizhou-Sichuan area had a certain fluctuation,and it increased at the rate of 7.232 2 gC · m-2 · a-1 in the past 20 years.The NPP was the highest in summer with an average value of 160.25 gC · m-2.It showed an average NPP value of 109.10 gC · m-2 in spring and 106.10 gC ·m-2 in autumn.The average value in winter was 54.03 gC · m-2,which is the lowest.