榆林市植被固沙作用年内变化情况研究

Study on Annual Variation of Vegetation Sand Fixation in Yulin City

为评估植被防风固沙效应的年内动态变化情况并为相关研究提供参考,以黄河中游水土流失重点治理区之一的榆林市为研究对象,基于2012年遥感影像资料等,按分辨率为1 km的栅格对单位面积植被的固沙量进行了逐月评估,结果表明:榆林市以县(区、市)为单元计算的单位面积植被年固沙量为6 375~15 371 t/km^(2),其时空分布差异显著,在时间上单位面积植被年固沙量约90%分布在3—6月,在空间上东南部黄土丘陵沟壑区单位面积植被年固沙量明显大于西北部风沙区的;季节变化对风蚀、植被生长及其防风固沙作用有明显影响,黄土丘陵沟壑区植被防风固沙作用对季节变化较为敏感。

In order to evaluate the annual dynamic change of vegetation windbreak and sand fixation effect and provide reference for related researches,Yulin City,one of the key control areas of soil erosion in the middle reaches of the Yellow River,was taken as the research ob⁃ject.Based on the remote sensing image data of 2012,the sand fixation capacity of vegetation per unit area was evaluated monthly according to the grid with a resolution of 1 km.The results show that Yulin City,the annual sand fixation capacity of vegetation per unit area calculated by county(district and city)is 6375-15371 t/km^(2),and its spatial and temporal distribution is significantly different.In terms of time,about 90%of the annual sand fixation of vegetation per unit area is distributed from March to June.Spatially,the annual sand fixation of veg⁃etation per unit area in the gullied rolling loess area in the southeast is significantly greater than that in the northwest sandy region.The sea⁃sonal change has obvious influence to the wind erosion,vegetation growth and its wind⁃break and sand⁃fixing effect,and the wind⁃break and sand⁃fixing effect of vegetation in the gullied rolling loess area is sensitive to the seasonal change.