青海省近10年草地植被覆盖动态变化及其驱动因素分析

Analysis of Vegetation Cover Change and Its Driving Factors over the Past Ten Years in Qinghai Province

草地是陆地生态系统的重要组成部分,认清其植被覆盖变化规律对草地可持续发展和草地生态系统的恢复具有重要意义。基于2005—2014年增强型植被指数(MODIS EVI)数据和气象数据,结合相关分析、残差趋势分析等方法,分析了10年间青海省生长季草地植被覆盖变化规律,以及气候因素和人类活动对其变化的影响。结果表明:(1)10年间青海省生长季草地EVI的年增长速率为0.0023,整体呈波动增加趋势,其中东部黄土高原区整体呈显著增加趋势,其次是青南高原区、柴达木盆地,环湖和祁连山区整体呈退化趋势。(2)青海省生长季草地EVI与温度和降水相关性显著,与平均温度和累积降水量的偏相关总体呈正相关关系,空间差异明显,与温度的关系更为密切。(3)从驱动因素来看,主要受气温驱动的区域有环湖和祁连山区(Ⅲ级)、青南高原区(Ⅳ级);主要受降水驱动的区域有东部黄土高原区(Ⅲ级和Ⅳ级);主要受气温和降水驱动的区域有柴达木盆地(Ⅱ级,Ⅲ级和Ⅳ级)、环湖和祁连山区(Ⅰ级和Ⅳ级)、青南高原区(Ⅱ级和Ⅲ级);其他区域主要受非气候因子驱动。(4)人类活动对青海省草地植被生长总体上呈正影响,尤其对于草地植被明显变化区域的生态系统建设和破坏起着主导的作用。

Grassland is an important part of terrestrial ecosystem.To recognize the law of vegetation change has important significance for sustainable development of grassland and restoration of grassland ecosystem.Based on the data of MODIS EVI and meteorological data from 2005 to 2014,we used correlation analysis and residual trend method to analyze the law of vegetation change of grassland in growing season,and the influence of climate factor and human activity on the change in ten years in Qinghai Province.The results showed that:(1)in ten years,the growth rate of grassland EVI in growing season was 0.002 3 per year in Qinghai Province,it had an fluctuating increasing trend as a whole;among them,the Loess Plateau in the eastern part had a significantly increasing trend,followed by southern Qinghai Plateau Area sub zone and the Qaidam Basin,Qinghai Lake-Qilianshan Mountain had a degradation trend;(2)grassland EVI in growing season in Qinghai Province had a significant relation with temperature and rainfall,had a positive partial correlation with temperature and rainfall as a whole,its spatial differences of were significant,and more closely related to temperature;(3)with respect to the driving factor,Qinghai Lake-Qilianshan Mountain(level three)and southern Qinghai Plateau area sub zone(level four)were mainly driven by temperature;the Loess Plateau in the eastern part(level three and level four)was mainly influenced by rainfall;the Qaidam Basin(level two,level three and level four),Qinghai Lake-Qilian mountain(level one and level four)and southern Qinghai Plateau Area sub zone(level two and level three)were mainly driven by temperature and rainfall;Other areas mainly influenced by non-climate factors;(4)human activity had a positive effect on grassland vegetation growth in Qinghai Province,especially played major role in the construction and destruction of ecosystem in significant change area of grassland vegetation.