京津风沙源区干旱时空特征及对植被变化的影响

Spatial and Temporal Variations of Droughts over the Beijing-Tianjin Sand Source Region and Their Effects on Vegetation Change

本文基于京津风沙源区27个站点1960—2014年逐月气温和降水数据,采用标准降水蒸散指数(SPEI),从干旱趋势、干旱面积和干旱频率等方面分析了研究区干旱的时空变化特征;在此基础上,利用SPEI和NDVI指数,分析了干旱对区域植被变化的影响。结果表明:(1)1960—2014京津风沙源区SPEI呈显著下降的趋势,多次严重干旱均出现工程实施的近15年。过去55年京津风沙源区大部分区域SPEI呈下降趋势,显著下降的区域主要集中在内蒙古草原地区。(2)1960—2014年轻度干旱、中度干旱和严重干旱的面积均呈上升的趋势。2001年和2009年严重干旱面积分别占整个研究区的49.00%和41.10%。(3)1960—2014年干旱频率从西北向东南呈递减趋势。1996—2014年干旱频率比1978—1995年和1960—1977年分别增长了7.59%和9.09%。京津风沙源区最长干旱持续时间都接近或超过半年。(4)1982—2014年研究区92.52%的区域SPEI和NDVI呈正相关关系,表明干旱会对区域植被产生重要影响。干旱趋势、干旱面积和干旱频率均表明,京津风沙源区干旱情况加重,尤其治理工程实施的近15年干旱程度更加严重。本文研究结果对京津风沙源区植被恢复重建具有重要的指导意义。

In this study,the monthly precipitation and temperature data from 27 station of Beijing-Tianjin sand source region(BTSSR)were utilized to compute standardized precipitation evapotranspiration index(SPEI)and analyzed the spatiotemporal drought patterns in the BTSSR for the period during 1960-2014.The impact of drought on vegetation change was also analyzed by SPEI and the normalized vegetation index(NDVI).The following were the results:(1)The SPEI showed a significant decrease over the past five decades at a rate of 0.16/10a(P<0.01),demonstrating a drying trend in BTSSR over the study period.Spatially,the SPEI of most stations were declining over the past 55 years.Moreover,the significant decreasing trend was found in the Inner Mongolia grassland.(2)The drought affected area of mild drought,moderate drought and severe droughts increased significantly from 1960 to 2014.The severe drought affect area in 2001 and 2009 accounted for 49.00%and 41.10%,respectively.(3)From 1960 to 2014,the drought frequency was decreasing from northwest to southeast.The drought frequency for the period 1996-2014 for the drought frequency increased to 22.22%,a difference of 7.59%and 9.09%from the previous sub-period 1978-1995 and 1960-1977.The drought durations of most stations in BTSSR were close to or more than six months.(4)A positive correlation between SPEI and NDVI was found from 1982 to 2014,indicating that drought has an important impact on vegetation.Using parameters,such as the long-term trend of drought,drought affected area,drought frequency and duration,it was demonstrated that the drought events increased during the study period,especially in the past 15 years.All of these findings will provide a scientific basis for the management of ecological restoration programs in the BTSSR.