近30年祁连山南坡生长季植被降水利用效率时空变化

Spatio-temporal variation of vegetation precipitation utilization efficiency in the growing season in the southern slope of Qilian Mountains from 1987 to 2017

基于1987-2017年降雨量数据、1987-2015年的GIMMS NDVI3g数据、及2001-2017年MODIS NDVI数据,运用累计降水利用效率估算及时间趋势模型,探讨了祁连山南坡地区的植被覆盖、降雨量和植被降水利用效率的时空变化特征。结果表明:(1)NDVI及PUE变化最大的两个区域为黑河谷地及门源盆地,门源盆地尤为显著;(2)1987-2017年间,降雨量呈上升趋势,符合"东南高,西北低"特征,趋势变化呈现出"东南低,西北高"特点,平均降雨量在300-400mm之间面积占比最大,约为60.45%;(3)NDVI与降雨量具有一致变化特征及规律,平均累计NDVI在3-4之间面积占比最大,约为52.54%;(4)平均PUE与PUE趋势变化均呈现出"东南高,西北低"趋势,且2000年之后,PUE呈减少趋势面积增加81.07%,即2000年之后,大部分区域植被健康状况有所下降。

Based on the rainfall data from 1987 to 2017,the GIMMS NDVI3g data from 1987 to 2015,and the MODIS NDVI data from 2001 to 2017,using the cumulative precipitation utilization efficiency estimation and time trend model,the vegetation coverage and rainfall in the southern slope of Qilian Mountain were discussed.And temporal and spatial variation characteristics of vegetation precipitation utilization efficiency were studied.The results showed that:(1)The two regions with the largest changes in NDVI and PUE were the Heihe Valley and the Menyuan Basin,especially in the Menyuan Basin.(2)Between 1987 and 2017,the rainfall showed an upward trend,which was consistent with the characteristics of"southeast high and low northwest".The trend change showed"lower southeast and higher northwest",and the average rainfall was between 300-400 mm.The maximum was about 60.45%.(3)NDVI had the same characteristics and regularity as rainfall,and the average cumulative NDVI was the largest in the area of 3-4,which was about 52.54%.(4)The average PUE and PUE trend changes showed a trend of"south-south high and low-southwest".After 2000,the PUE showed a decreasing trend area of 81.07%.After 2000,the vegetation health status of most areas decreased.