【摘要】 基于MODIS-NDVI、DEM和气象数据,分析柴达木盆地2000—2015年植被覆盖度(FVC)时空变化特征,并与降水、温度、日照时数、相对湿度、蒸散量和海拔进行相关、偏相关或叠加分析,探讨FVC与各环境因子的关系。结果表明:FVC整体自东南向西北内陆呈半环状递减,FVC集中在20%以下,人类活动及径流等打破植被地带性规律;2000—2015年FVC明显改善,广泛分布于盆地中西部地区,2001—2002年年际变化最显著;FVC与降水、相对湿度以正相关为主,与温度关系不显著,与日照时数和蒸散量主要为负相关,降水对FVC贡献最大,温度通过影响蒸散量等间接影响FVC,而土壤蒸发对蒸散量的影响大于植物蒸腾;FVC与等高线空间分布较吻合,FVC在2 800～2 900 m和4 600～4 700 m出现两个峰值,4 700 m以上FVC迅速降低。更多还原

【Abstract】 The relationship between fractional vegetation cover and environmental factors is one of the important contents for the study of the ecosystem in arid regions.In this paper,we analyzed the temporal and spatial variation characteristics of fractional vegetation cover from 2000 to 2015 in the Qaidam Basin,Qinghai Province,China based on MODIS-NDVI.Combined with DEM data and meteorological data of the basin,the correlation analysis,partial correlation analysis or overlay analysis between fractional vegetation cover and precipitation,temperature,sunshine duration,relative humidity,evapotranspiration,and altitude were calculated to explore the response characteristics of fractional vegetation cover to major environmental factors.The results showed that the fractional vegetation cover in the Qaidam Basin displayed a semi-annular decreasing trend from the southeast to the northwest.The overall fractional vegetation cover was below 20%.The human activities and the distribution of runoff broke the regularity of vegetation zonal distribution and thus affected fractional vegetation cover significantly.In the context of global warming,the fractional vegetation cover was increased significantly during the time period from 2000 to 2015,with most of the regions being widely distributed in the central and western and parts of the eastern mountainous region of the basin.Furthermore,the most obvious inter-annual variation occurred from 2001 to 2002.Especially the improvement trend of forest,grassland and meadow vegetation was particularly obvious.The relationship between fractional vegetation cover and different meteorological elements was different.The fractional vegetation cover was positively correlated with precipitation and relative humidity,and negatively correlated with sunshine hours and evapotranspiration.The relationship between fractional vegetation cover and temperature was not significant.Among them,the precipitation contributed the most to the fractional vegetation cover and was the major limiting factor to affect the growth of vegetation in the basin.Temperature indirectly affected fractional vegetation cover by affecting evapotranspiration,and contributed more to evapotranspiration than precipitation.Meanwhile,the influence of soil evaporation to evapotranspiration was much higher than that of vegetation transpiration.There was consistency of the spatial distribution between fractional vegetation cover and altitude,which meant that fractional vegetation cover had a good consistency with the spatial distribution of contour lines.Vegetation vertical differentiation was evident.Two peak values occurred in the areas of 2 800-2 900 m and 4 600-4 700 m respectively due to the influence of water source and temperature,while fractional vegetation cover was decreased rapidly above 4 700 m.This paper clarifies the relationship between multiple environmental factors and fractional vegetation cover,and makes clear the response characteristics of vegetation to major environmental factors under the background of global warming and drying,which has a great significance for the study of other ecological environment and climate change in arid regions.更多还原