Study On The Change Of Soil Water Storage Ability In The Process Of Vegetation Restoration On Returning Cultivated Land In Yanhe Watershed

The effects of the vegetation restoration process on soil physical properties and soil water-storage capacity is very complex.In this paper,the Yanhe watershed in the loess hilly-gully region is taken as an example,and the community biomass and soil water-storage capacity such as soil bulk density and porosity were investigated.The characteristics of soil water-storage capacity under different succession stages,different micro topographic features and landscape pattern evolution were analyzed,and the effect of vegetation restroration process on soil water storage in loess hilly-gully region was deciphered.The main conclusions are as follows:(1)The aboveground biomass,root biomass and vegetation coverage of the natural restoration vegetation communities in the loess hilly region showed an increasing trend,among which all indexes showed a significant growth trend in the natural restoration of 0-30 a,and grew slowly in 30-50 a.(2)The soil bulk density of 0-20 cm soil layer is less than 20-40 cm in the same restoration stage of natural restoration of abandoned farmland.In the natural restoration of 30 a,the surface and bottom soil bulk density decreased by 6.02% and 6.60%,respectively.The surface soil bulk density of the natural restoration(30a)was significantly reduced(P <0.05),while the soil bulk density gradually increased and stabilized during the natural restoration of 30-50 a.(3)During the natural restoration,the total soil porosity and capillary porosity increased significantly,and both reached the peak in 30 years.The soil non-capillary porosity decreased significantly in the early stage of natural restoration(0-30a),and the soil porosity gradually stabilized after 30 years.Soil total water storage capacity and capillary water storage capacity increased significantly in the period of 0-30 a and reached the peak value at 30 a,while the non-capillary water storage capacity decreased significantly at 30 a and reached the bottom.The soil water-storage capacity was significantly improved in the early stage(30a),and then gradually stabilized.(4)Under the same terrain,soil bulk density of abandoned farmland increased with soil depth,while soil porosity(total soil porosity,capillary porosity and non-capillary porosity)and soil water storage capacity(capillary water storage capacity,Non-capillary water storage capacity and Total water storage capacity)decreased with the increase of soil depth.The difference of water storage capacity at different site conditions was not obvious.(5)Between 1990 and 2010,forest land was the most important land type.The spatial distribution of soil water storage capacity showed obvious characteristics of vegetation zonality.The southwest of the watershed belonged to the forest belt,which had a better soil water storage capacity.While the middle of the watershed belongs to the forest-grassland transition zone,which had a lower soil water storage capacity.The soil bulk density is between 1.15-1.35 g?cm-3,the total soil porosity is between 43% and 55%,and the capillary porosity is between 8.8 and 10.2%,non-capillary porosity of 40-48%,total water storage capacity between 2985-3263 t?hm-2,capillary water storage capacity of 525-638 t?hm-2,non-capillary water in the range of 2400-2775 t?hm-2.With the evolution of land use,the soil water-storage capacity decreased first and then increased.