Soil Structures And Hydrology-physic Properties Of Typical Planted Forests In Catchment Of Huangqian Reservoir

This article regards water boundaries of municipal water source—Huangqian district as studying area,six kinds of typical forest vegetation-the sunny side of the mixed forest of Pinus tabulaeformis and Acer mono Maxim, the shade side of the mixed forest of Pinus tabulaeformis and Acer mono Maxim,Quercus acutissima,Castanea mollissima,Platycladus orientalis in the area as the research object(in contrast to grassland),mainly discusses soil structure,physical character of soil,soil infiltration,dynamical Changes of soil water of different forest,providing theoretics bases and technique supporting for the choice of forest and the combination of forest structure in the construction of water boundaries of municipal water source.The results are follows:(1) By analyzing two indexes of particle-size distributions—Cu and Cs, and two indexes of Soil aggregate evaluation—MWD and FD,the result shows:①The soil structure of forest was better than grassland,and among forests, the soil structure of the mixed forest of Pinus tabulaeformis and Acer mono Maxim is better than Quercus acutissima,Castanea mollissima,Platycladus orientalis.A good forest structure could improve the even degree and range of distribution obviously,and improve the porosity.The soil structure of mixed Forest with needle and broad leaves is the best.②The FD of the mixed forest of Pinus tabulaeformis and Acer mono Maxim is lower than Quercus acutissima,Castanea mollissima,Platycladus orientalis and grassland,while its mean weight diameter(MWD) is higher than Quercus acutissima,Castanea mollissima,Platycladus orientalis and grassland,which explains that the mixed forest with needle and broad leaves have better soil structure and soil permeability.(2) Physical and hydrologic character of soil By analyzing the soil density,the porosity(the total porosity,the capillary porosity,the non-capillary porosity),water conservation capacity of soil(the saturated moisture,the capillary capacity) the result shows:①The soil density of six forest stands all increase with the soil depth increasing.In 0～10cm layer,the soil density of Castanea mollissima is minimum which is 1.05 g/cm~3,the next is Quercus acutissima(1.05 g/cm~3),the sunny side of the mixed forest of Pinus tabulaeformis and Acer mono Maxim(1.12 g/cm~3),Platycladus orientalis(1.18 g/cm~3).The soil density of grassland is the larger than that of forest(1.19 g/cm~3).In 10～20cm layer,the soil density of the shade side of the mixed forest of Pinus tabulaeformis and Acer mono Maxim(1.09 g/cm~3)＜Castanea mollissima(1.16g/cm~3)＜Quercus acutissima(1.18 g/cm~3)＜the sunny side of the mixed forest of Pinus tabulaeformis and Acer mono Maxim(1.23 g/cm~3)＜grassland(1.28g/cm~3)＜Platycladus orientalis(1.36g/cm~3).In 20～30cm layer,the order from high to low of the soil density:the shade side of the mixed forest of Pinus tabulaeformis and Acer mono Maxim,Quercus acutissima,the sunny side of the mixed forest of Pinus tabulaeformis and Acer mono Maxim,Castanea mollissima,Platycladus orientalis,grassland.In 30～40 layer,the change of the the soil density of six forests is not remarkble in constract to that of 20～30cm.Because of the influence of artificial cultivation,the soil density of Castanea mollissima in all layers is low,and the soil structure is better than others.②The soil capillary of six forests stands(the total porosity,the capillary porosity,the non-capillary porosity) all decrease with the soil depth increasing. The porosity of forest are all higher than grassland;the porosity of mixed forest (the total porosity,the capillary porosity,the non-capillary porosity is (49.75%,12.75%,37%respectively)is higher than pure forests.(48.8%,12.4%,35%respectively).This shows that the mixed forest have preferable ability of ameliorating soil structure.The porosity of same forests of different slope exposure is different.The porosity(the total porosity,the capillary porosity,the non-capillary porosity is 49%,13.31%,36%respectively )of the sunny side of the mixed forest of Pinus tabulaeformis and Acer mono Maxim is higher than that of the shade side(the total porosity,the capillary porosity,the non-capillary porosity is 45.75%,9.5%,36%respectively)The porosity of broad-leaved forests is better than that of needle-leaved forests of same slope exposure.For example,the total porosity of Quercus acutissima is 49.5%,12.75%,37%respectively,while that of Platycladus orientalis is 45.75%,12%,34%respectively.③The saturated moisture and the capillary capacity of six forests are all decrease with the soil depth increasing;The moisture of all layers of mixed forest is higher than pure forest and grassland.For example,the saturated moisture of mixed forest(46.5%averagely of all layers)＞Platycladus oriental(43%averagely of all layers)＞grassland(38.25%averagely of all layers).