Key Laboratory of Regional Climate-Environment for Temperate East Asia,Institute of Atmospheric Physics,Chinese Academy of Sciences
中国各区植被覆盖和气候特征多样，植被覆盖变化和气候变化及植被对气候因子的响应存在明显的区域差异，研究不同气候区植被变化及其与气候变化的关系可以为各区针对性地应对气候变化、制定植物保护和生态环境修复政策提供科学依据。本文首先基于中分辨率成像光谱仪（MODIS）的土地覆盖数据，根据植被带的分布确定了划分中国干湿区的指标，其次利用归一化植被指数（NDVI）分析不同干湿区域NDVI的时空变化特征，最后探讨了NDVI变化与温度、降水的关系。结果表明：（1）中国区域200 mm、500 mm和800 mm年降水量等值线分别与荒漠/草地、草地/农田、农田（草地）/森林植被带的分界线吻合，气候过渡带对应着植被过渡带，这些等值线作为划分干湿气候区的指标比较合理。（2）中国年平均NDVI从东南向西北递减，从小到大依次为干旱区（0.11）、半干旱区（0.35）、半湿润区（0.57）、湿润区（0.68）。1982~2015年中国大部分区域NDVI呈显著的增加趋势，区域平均的NDVI在干旱区、半干旱区分别以0.002/10a、0.008/10a的趋势显著增加，在半湿润区和湿润区也呈现增加趋势，但不显著。（3）四个干湿区的年平均温度和NDVI均呈显著正相关，仅干旱区、半干旱区年降水和NDVI呈显著正相关，半湿润区和湿润区的年降水与NDVI呈微弱负相关。温度对四个干湿区NDVI时间变化的解释率相差不大，均在30%左右；降水对NDVI时间变化的解释率低于温度，降水对干旱区（18%）和半干旱区（20%）NDVI时间变化的解释率较大，降水主要影响着北方地区植被的生长。（4）月平均NDVI随着温度和降水的增加都有显著的增加趋势，半湿润区的NDVI随温度升高增长的速率（0.026/℃）最快，半干旱区的NDVI对降水最敏感，随降水增多增加的速率为0.027/mm。
There are diverse vegetation covers and climate characteristics in various regions of China. And there are obvious regional differences in vegetation cover change, climate change and response of vegetation to climate factors. The study of vegetation changes and its relationship with climate change in different climate regions can provide a scientific basis for responding to climate change and formulating plant protection and ecological environment restoration policies in various regions. Firstly, based on the land cover data of MODerate-resolution Imaging Spectroradiometer (MODIS), the indexes for dividing dry and wet areas in China were determined according to the distribution of vegetation zones. Secondly, the temporal and spatial variation characteristics of Normalized Difference Vegetation Index (NDVI) in different dry and wet areas were analyzed by using vegetation index NDVI. Finally, the relationship between NDVI and temperature/precipitation was discussed. The results showed that: (1) 200 mm, 500 mm, and 800 mm annual precipitation contours are consistent with the boundaries of the vegetation zones of barren land and grassland, grassland and cropland, and grassland/cropland and forest, respectively. The climate transition zones correspond to the vegetation transition zones. These lines are reasonable indexes of dry/wet climate zoning. (2) Annual averaged Normalized Difference Vegetation Index (NDVI) decreases from Southeast to Northwest, from small to large followed by the arid area (0.11), semi-arid area (0.35), semi humid area (0.57) and humid area (0.68). The NDVI increases significantly in most regions of China during 1982-2015. Regional averaged NDVI increases significantly in arid area and semi-arid area with a trend of 0.002/10a and 0.008/10a, respectively, and it also increases in semi-humid area and humid area, but not significantly. (3) There are significant positive correlations between annnual averaged temperature and NDVI in the four dry and wet areas.The annual precipitation are significantly correlate to NDVI only in arid and semi-arid areas, and there are weak negative correlations between annual precipitation and NDVI in semi-humid and humid areas. The temperature explains about 30% of the temporal changes of NDVI in the four dry and wet areas. The explanation ratios of precipitation to the temporal changes of NDVI are lower than thoses of temperature. Precipitation explains greatly to the temporal changes of NDVI in arid areas (18%) and semi-arid areas (20%), and precipitation mainly affects the growth of vegetation in the northern China. (4) The monthly average NDVI has a significant increasing trend with the increase of temperature and precipitation. The increasing rate (0.026/℃) of NDVI in semi-humid area is the fastest with the increase of temperature. The NDVI in semi-arid area is the most sensitive to precipitation, and the increasing rate with the increase of precipitation is 0.027/mm.