植被恢复工程对黄河中游土地利用/覆被变化的影响

Impact of the Grain for Green Project on the Land Use/Cover Change in the Middle Yellow River

剧烈的人类活动可快速地改变土地利用/覆被变化(LUCC)格局,并对地表参量和水文要素产生深刻的影响。论文以退耕还林/还草生态工程(Grain for Green Project,GGP)的重点区黄河中游为例,利用5期土地利用数据,定量分析了区域LUCC的过程与趋势,并探讨了GGP对下垫面地表参量及水文要素的影响。结果表明:1)GGP并未显著地改变研究区土地利用空间分布格局,但改变了各土地类型的转换速度和平衡状态。GGP实施前各类型间相互转换频繁,处于动态平衡态势,而GGP实施后以土地类型单向转换为主,处于不平衡态势,以耕地单向转为林草地为主。2)不同子流域间LUCC存在差异。GGP前汾河流域变化速度较其他区域快,呈准平衡状态;工程实施后的前期,河龙区间与渭河流域的净变化率以及总变化率较快,而后期差异不显著,呈不平衡状态。3)GGP显著地改变了下垫面地表参量和水文要素。GGP的实施使得NDVI、LAI和发射率显著增加,而反照率显著下降,以河龙区间尤为显著;径流系数显著下降,而蒸散发系数显著增加,尤以河龙区间表现显著。

Intense human activity can quickly change the pattern of the land use/cover, and have a significant impact on the surface parameters and hydrological elements. The middle Yellow River, a typical region of Grain for Green Project（GGP）, was used to detect the process and trend of LUCC and identify the impact of GGP on surface parameters and hydrological elements. The results indicated that： 1） Although GGP did not significantly changed the distribution pattern of land use, it changed the speed of land use change and the balance status of land uses. After the implementation of GGP, the bidiredictional change of land use turned to one- way change from farmland to forest and grass. 2） There were significant differences of LUCC among subbasins. Before GGP, the change speed of LUCC in the Fenhe Basin was faster than in other regions, and was in quasi-balance status. In the early period of GGP, the net change speed and total change speed in Helong region and Weihe River Basin was faster than in other regions. However, there was no significant difference of speed in the end period of GGP, and it was in unbalanced status. 3） The GGP had significantly changed the terrestrial parameters and hydrological elements. The GGP implementation resulted in the significant increase of NDVI, LAI and emissivity and decrease of albedo, especially in the Helong region.In addition, the runoff coefficient decreased significantly, while evaporation coefficient increased significantly, especially in the Helong region.