泾河流域植被景观格局对流域径流的调节作用

对黄土高原腹地泾河流域12个子流域植被景观格局和流域径流动态的关系进行了探讨。结果表明景观层次上植被的整体空间格局对流域径流动态有着如下调节作用:(1)泾河流域4种植被景观类型中,森林灌丛植被景观流域年径流量最大,径流年内分配比较均匀,但年际变化很大;其次为复合植被景观,农业植被景观流域径流量较小,且主要集中在汛期;草地植被景观流域径流极小,主要发生在汛期的7~8月份,年际变化比较小。(2)在主要植被景观指数中,景观破碎度、景观多样性与流域径流正相关,景观聚集度、景观优势度与流域径流负相关,景观形状与流域径流相关不显著。(3)结构复杂的植被景观对流域径流具有较好的调洪补枯作用。随着景观破碎度和景观多样性的增大,流域径流年内分配趋于均衡;而随景观聚集度的增大,流域径流年内分配则趋向集中,景观形状对流域径流调节作用不明显。(4)多样性高的植被景观可降低极端径流出现,维持流域生态系统的稳定性。

Regulation of Vegetation Landscape Pattern on Runoff in Watershed of Loess Plateau

The landscape pattern is indicator of the regional climate and many other factors, and it also has significant effect on runoff. The vegetation landscape pattern and runoff in Jinghe river basin on the Loess Plateau was studied in this paper, the result showed as follow: Average runoff and its yearly variation increased with the vegetation landscape structure turned to complex and landscape diversity enlarged. Compared with grass landscape watershed, runoff of forest and shrub watersheds was bigger and more uniform, while that of compound landscape watersheds was inferior. The landscape contagion index and dominant index related to runoff positively, while the landscape diversity index and the landscape patchiness index related to runoff negatively, and the landscape shape index did not relate to watershed runoff. The annual variation of runoff turned to uniform with the landscape patchiness index and landscape diversity index increased, and it turned to extreme with the landscape contagion index and landscape dominant index increased, and it did not relate to landscape shape index. The extreme runoff (very big or very small) of watershed decreased with the landscape diversity increasing.