Research On The Soil Physical And Chemical Properties And Water Capacity Of Forestlands Converted Of Farmland During 16 -20 Years In Western Shanxi Province

To explore the differences of water-holding capacity of soil physical and chemical properties in Loess Plateau area of Western Shanxi Province, secondary forest (SF)banned for nurture from sloping field, Pinus tabulaeformis X Robinia pseudoacacia (P X R) plantation, Robinia pseudoacacia (R) plantation and Pinus tabulaeformis (P) plantation converted of sloping field were examined based on field investigations and laboratory analyses, at the same time the farmland as a control. Through the field investigation and laboratory experiments, the physicochemical properties of soil and water holding capacity of the area in recent five years were compared and analyzed. The results showed that:(1) On the soil physical and chemical properties in different forestlands,along with the increasing length of farmland converted to forestlands, soil bulk density were decreased, soil porosity, saturated hydraulic conductivity, organic matter content showed increasing trend,but the difference was not significant change year by year.In addition to soil particles composition, the forestlands converted of farmlands after 19 years and 20 years compared with 16 years is significantly improved;The soil organic matter, soil porosity, soil root content and saturated hydraulic conductivity in lm layers were showed:SF>P XR>R>P. The more the soil root, the higher the soil organic matter, the lower the soil density, the bigger the saturated hydraulic conductivity, the more the soil capillary porosity.(2) On the hydrologic functions in three kinds of plantted forestland from farmland and secondary forest, forest litter stock volume showed increasing trend year by year,and maximum water-holding capacity and effective water-holding capacity were SF>P X R>R>P, and a significant difference was between the 4 kinds of forest. Soil saturated water content and capillary water holding capacity of 4 kinds of forests in lm layer were SF>P XR>P>R. Integrated of litter layer and soil layer water holding capacity, the forest maximum water holding capacity and water holding capacity were found the same trend:SF>P ×R>R>P>CK.Water-holding capacity of the soil layer is the main aspect of the forestlands hydrological functions.By comparing the physical properties and water holding capacity of forest land of the study area in recent 5 years after returning farmland to the forest, the forests were significantly improved comparing of farmland. The effect of returning farmland to secondary forest is the best, followed by mixed forest, and artificial pure forest. It is showed that the secondary forest should be the main reference of vegetation restoration in this area.