大规模植被重建背景下的黄土高原流域土地利用时空演变

Spatio-temporal Changes of Land Use/Cover Driven by Large-scale Vegetation Restoration on Watershed in the Loess Plateau

运用RS和GIS技术,全面分析黄土高原北洛河上游土地利用/覆被时空演变。研究结果表明,近20余年,受大规模人工植被重建驱动,流域土地利用结构由农牧占绝对主体转变为农、林、牧均等复合,植被覆盖率和森林覆盖率分别提高至77%和24%,变化集中于1997-2004年。期间,耕地、草地大幅缩减,林地大幅扩张,建设用地增幅明显,农、林、牧和建设用地变化迅速、剧烈。受植被重建规模和降水的区域差异,林地和水域分布重心朝东南转移,建设用地、耕地和草地朝西北转移。耕地、疏林地和灌木林在沟间地的变化较沟谷地剧烈,草地和建设用地相反,坡、沟单元植被覆盖率分别提高至75%和81%。耕地、疏林地和灌木林地在陡坡的变化强于缓坡,建设用地相反,草地和有林地在陡、缓坡变化幅度相当。植被重建后,流域景观联通性和聚集度降低,斑块镶嵌度和景观多样性提高,破碎度增大。

Based on GIS and RS technology,the land use/cover change（LUCC）of the upper reaches of Beiluohe river in Loess Plateau was comprehensively analyzed.Results showed that,in recent twenty years,driven by large-scale artificial vegetation restoration,the watershed land use structure changed from farmland and pasture played a dominant role to equal composite of farmland,forestland and pasture.The vegetation coverage and the forest coverage increased to 77%and 24%respectively.The LUCC mainly occurred during1997 to 2004.During this period,farmland and grassland decreased greatly,forestland increased greatly and construction land increased obviously.All of the farmland,forestland,pasture and construction land changed rapidly and acutely.Due to the regional difference of the artificial vegetation restoration scale and the rainfall distribution,gravity centers of forestland and waters transferred to southeast,but construction land,farmland and grassland to northwest.Farmland,woodland and shrubland changed more greatly in slop-up land than gully land,grassland and construction land were opposite.The vegetation coverage of slop-up land and gully land increased to 75%and 81%respectively.Farmland,woodland and shrubland changed more in steep slopeland than gentle slopeland,construction land was opposite,and grassland and forestland had quite changing range in both of steep slopeland and gentle slopeland.After vegetation restoration,the continuity degree and aggregation degree of watershed landscape decreased,the patch mosaic degree and the landscape diversity increased,and the extent of fragmentation increased.