了解草地覆盖动态在生态环境保护和建设上有重要意义。基于GIMMS NDVI3g数据、气象数据和高程数据分析了1982—2015年中国北方草地NDVI时空动态及对气候变化的响应。结果 表明:(1)1982—2015年中国北方草地NDVI以增加趋势为主(占76%),增速为0.002/10 a。其中,坡地草地的增加速率最大(增长速率为0.001/10 a),高山亚高山平原草原变化速率最小,其他4种草地类型速率为平原草地NDVI增长速率>高山亚高山草甸>荒漠草原>草甸;(2)NDVI变异系数均值为0.078,变化相对稳定(Cv<0.15);(3)Hurst指数均值为0.42,结合NDVI变化趋势结果发现未来草地NDVI变化趋势主要以下降为主(0<H<0.5,占79.8%);(4)降水是影响北方草地生长的主要气候因子。除昆仑山脉、青海高原东坡坡底及小兴安岭等海拔较高区域外,其他地区(占92.4%)的降水与NDVI呈显著相关关系。温度与草地NDVI主要以正相关为主(占62.7%),呈负相关关系的区域集中在内蒙古高原、黄土高原西南部、准噶尔盆地和塔里木盆地等较为干旱地区。以上研究结果可为草地资源管理、生态环境保护、荒漠化防治提供重要参考信息。
Understanding the spatial-temporal changes of grassland is of great significance to regional environmental protection and ecological construction. The spatial-temporal variation characteristics of grassland was analyzed based on the GIMMS NDVI 3g data, meteorological data and DEM data for northern China during the period 1982 to 2015. The results indicate that:(1)NDVI mainly showed growth trend from 1982 to 2015, with growth rates of 0.000 2/decade(76%); the growth rate of slope grassland was the(0.001/10 a), the growth rates of alpine and sub-alpine plain grassland were the smallest, and the growth rates of the NDVI of the other four grassland types decreased in the order: plain grassland>alpine subalpine meadow >desert grassland>meadow;(2)the average coefficient of variation of grassland NDVI was 0.078, with the stable state(Cv<0.15);(3)the average Hurst value was 0.42; according to the coupling results of NDVI and Hurst index, it is found that the future NDVI change trend of the grassland will mainly reduce(0<H<0.5, accounting for 79.8%);(4)precipitation was the main factor for grassland growth in northwest China except for higher latitudes; In snow-covered areas, 92.4% of the precipitation was favorable for NDVI growth except Kunlun Mountains, the bottom of the eastern slope of the Qinghai Plateau temperature and the Iljehari-Alin, precipitation in other areas and NDVI had positive correlation; the NDVI of grassland was mainly positive correlation(62.7%)with temperature, and the negative correlation areas concentrated in Inner Mongolia Plateau, the southwest of Loess Plateau, Junggar Basin and Tarim Basin. The above results are expected to provide important reference information for grassland resource management, ecological environment protection and desertification control.
