中国草原区植被变化及其对气候变化的响应

利用1982~2006年GIMMS NDVI和气象数据,探究中国草原区植被变化及对气候的响应。结果表明,近25 a中国草原区植被覆盖总体呈上升趋势,但季节变化空间差异明显。春季温度对温带典型草原、高寒草甸草原和高寒典型草原植被生长有重要影响,而夏季和秋季温度同样对高寒草甸草原影响显著;夏季降水增多能明显促进夏季温带荒漠草原植被生长。除8月份以外,温带草原5~9月NDVI均与前一个月降水显著正相关;在生长季内,高寒草原NDVI与同期温度显著正相关,但8月份除外。此外高寒草原植被在生长最旺盛时期对降水变化存在1~3个月滞后期。

Vegetation Change and Its Response to Climate Change in Grassland Region of China

This study analyzed the variation trend of vegetation NDVI and its response to climate change in grassland region of China by employing MODIS NDVI and meteorological data from1982 to 2006. Trend analysis, correlation analysis and spatial statistical analysis were carried out to investigate variation characteristics and spatial distribution pattern of vegetation NDVI, and analyze the relations between vegetation NDVI and meteorological factors. For temperate grassland region of China, growing season NDVI decreased gradually from northeast to southwest, and the grassland types from northeast to southwest are temperate meadow, temperate typical grassland and temperate desert grassland. For alpine grassland region of China, growing season NDVI was smaller overall than that of temperate grassland region, and it decreased on the whole from east to west, with the largest values concentrating in the east alpine meadow grassland. The results indicated that growing season NDVI increased on the whole in recent 25 years, but the spatial differences of seasonal changes were obvious. The largest increase of monthly NDVI occurred in August for temperate grassland region and in July for alpine grassland region. In the aspect of climate change, temperature showed obvious increase trend in the whole grassland region of China, while precipitation changes were not significant. For temperate grassland, spring temperature played an important impact on the vegetation growth of temperate typical grassland. The increase of summer precipitation could obviously promote the vegetation growth of temperate desert grassland. Monthly correlation analyses results showed that temperate grassland vegetation NDVI was significantly positively correlated with temperature in April, and May NDVI was significantly positively correlated with temperature in March and April. By contrast, the increase of June temperature could inhibit the growth of temperate grassland plants during the same period. In terms of precipitation, temperate grassland vegetation NDVI was significantly positively correlated with the previous month's precipitation (except August). April NDVI was significantly negatively correlated with precipitation in February, indicating that the low temperature in February could limit the growth of temperate grassland at the beginning of the growing season. Precipitation in June and July was significant for temperate grassland vegetation growth during the same time period, and the effect of August precipitation on vegetation growth was remarkable in September and October. For alpine grassland, spring temperature played an important impact on the vegetation growth of alpine meadow grassland and alpine typical grassland; summer and autumn temperatures had significant effect on alpine meadow grassland vegetation growth. Monthly correlation analyses results showed that monthly (April to October ) alpine grassland vegetation NDVI was significantly positively related to the air temperature during the same time period (except August), and temperature in August could affect alpine grassland vegetation growth in September. In addition, during the most vigorous growth period, alpine grassland vegetation had a time lag of 1-3 months for precipitation.