退耕还林背景下北方农牧交错带土壤保持功能时空变化

Spatiotemporal Variations of the Soil Conservation in the Agro-pastoral Ecotone of Northern China Under Grain for Green Program

为明析"退耕还林"政策实施以来北方农牧交错带土壤保持功能的时空变化规律,以对下一轮的政策实施提供理论依据,基于该区2000年、2018年土地利用、土壤、降雨及DEM等数据,通过InVEST模型评估了该区近20年来的土壤保持功能及其变化,并分析了"退耕还林"工程对该区土壤保持的影响。结果显示:(1)2000—2018年,该区土壤保持量由214.76亿t增长至214.93亿t,单位面积土壤保持量增长为0.356 t/hm^(2)。(2)土壤保持量在林、草地类型中占比较高,地形上随坡度梯级升高而显著上升,空间上东南部多而西北少;(3)"退耕还林"区土壤保持量增长占总增量的近60%(1014.50 t)。综合来看,"退耕还林"政策是北方农牧交错带土壤保持功能提高的主要原因。

Understanding and assessing spatiotemporal changes of the soil conservation is critical for the next round of GFGP(Grain for Green Program)implementation.Based on this,through the datasets of land use,soil,rainfall and DEM of the agro-pastoral ecotone of northern China(AENC)in recent two decades,soil conservation and its variations in views of the quantity,slope,and distribution were estimated using InVEST model.We focused on analyzing the impact of the GFGP implementation on the soil conservation function in the AENC.The results indicated the followings.(1)From 2000 to 2018,the total soil conservation increased from 2.1476×10^(10)tons to 2.1493×10^(10)tons with an increase of 0.356 tons/hm2.(2)The soil conservation function of woodland and grassland performed best,and soil conservation reached 863.62 tons/hm^(2)and 520.39 tons/hm^(2),respectively.Specifically,the average soil conservation increased significantly with the increase of slope.Meanwhile,the soil conservation showed a distribution of high level in southeast and low level in southwest;(3)The increase of soil conservation in GFGP area accounted for approximately 60%(1014.50 tons)of the total increment.Generally,GFGP played a crucial role in the improvement of soil conservation function in the AENC,and woodland and grassland contributed the most.