Soil Infiltration And Soil Water Retaining Property Of Different Vegetation Models In The Converting Farmland To Forest In Southwest Regions Around Sichuan Basin

Because,rainwater distribute uneven in hilly of Sichuan.Rainstorm and seasonal drought led to the frequent occurrence of soil erosion and land productivity in the local forestry industry is to limit the main factor.1998,the district implemented a returning farmland to forests.Soil infiltration basin hydrologic cycle process is an important component.In-depth analysis Basin Southwest Mountain hilly area of soil infiltration and water conservation function,that is the area of soil erosion awareness of the foundation.In this paper,the Hongya County of Sichuan Province three vegetation patterns(Betula luminifera forests,Arundinaria amara forests,and Bambusa pervariabili-s×Dendrocalamopsis oldhami forests),farmland as comparison,The process of soil infiltration,soil physical properties positioning observation and study.Choose a representative locations install infiltration tube(d=20 cm)in the runoff field of different vegetation patterns,repeated three times,collecting soil samples.Through four years beginning on soil infiltration rate,steady infiltration rate,cumulative infiltration capacity and runoff and soil water storage capacity and research and choose a suitable model of infiltration,explore different vegetation patterns hydrological Physics characteristics of the soil,revealing different vegetation patterns of soil and water conservation function,based on the measured data to determine the most suitable area returning farmland to forest vegetation patterns.The following main results.1 Different forest soil vegetation patterns of non-capillary water capacity were greater than farmland; With the passage of time,improve soil porosity.Except Bambusa pervariabili-s×Dendrocalamopsis oldhami forests model,the soil vegetation model for the effective storage capacity of agricultural land～1.6 to 2.1 times,non-capillary water retaining capacity and effective storage capacity of are Arundinaria amara forests the largest and second Betula luminifera forests.2 four-year observation period,Arundinaria amara forests and Betula luminifera forest prime infiltration rate of soil over time have risen situation.Betula luminifera forest the stable infiltration rates of the soil had increased.Bambusa pervariabili-s×Dendrocalamopsis oldhami forests the stable infiltration rates of the soil and the stable infiltration rates of the soil has been dropping,prime infiltration rate of the farmland soil had increased,the stable infiltration rates of the soil has been dropping.Different forest vegetation patterns prime infiltration rate of the soil and the stable infiltration rates of the soil were ranked as follows:Arundinaria amara forests＞Betula luminifera forests＞farmland＞Bambusa pervariabilis×Dendrocalamopsis oldhami forests.3 2003,different patterns of accumulation of soil infiltration capacity as follow:Arundinaria amara forests＞farmland＞Bambusa pervariabilis×Dendrocalamopsis oldhami forests×Betula luminifera forests 2006,different patterns of accumulation of soil infiltration capacity is the greatest Arundinaria amara forests,second Betula luminifera forests.Testify that the Arundinaria amara forests Can effectively weaken the surface flow yield,reduce surface soil erosion.Betula luminifera forests in the early stage of this experimental,the water retaining capacities of the soil and infiltration capacities of the three vegetation model of a worst,With vegetation growth,its infiltration capacities of the soil significantly to exceed over farming and Bambusa pervariabilis×Dendrocalamopsis oldhami forests..Inferior to Arundinaria amara forests.The improve function for increasing growth.Bambusa pervariabilis×Dendrocalamopsis oldhami forests the water retaining capacities of the soil and infiltration capacities of the soil has been an obvious decline,less than Betula luminifera forests and farmland.4 2003,surface flow yield as follows:Betula luminifera forests＞farmland＞Bambusa pervariabilis×Dendrocalamopsis oldhami forests＞Arundinaria amara forests.From the 2006,surface flow yield as follows:farmland＞Bambusa pervariabilis×Dendrocalamopsis oldhami forests＞Betula luminifera forests＞Arundinaria amara forests.Note Betula luminifera forests on soil improvement good effect.But Arundinaria amara forests and Bambusa pervariabilis×Dendrocalamopsis oldhami forests the infiltration capability had fallen,surface flow yield increasing trend.5 The four years of data on three infiltration model fitting,in accordance with decision factor in the selection of the most suitable areas Kostiakov3 parameter model-at f=n+b(b=f₀t).20 CM layers of soil temperature(X1),to the initial soil surface Water Content(X2),the initial soil the bottom water content(X3),non-capillary soil porosity(X4),total soil porosity(X5),the sand content in the soil(X6) Soil physical clay content(X7),coarse silt content(X8)Eight factors for variables,180 minutes of cumulative infiltration is the dependent variable.Building soil cumulative infiltration model.Forecast for 180 minutes of cumulative infiltration H180.According Kostiakov3 parameter model to simulate the process of infiltration.Method 1,according to the eight conventional soil physical parameters observed values of the soil infiltration model of the three parameters a,n,b make a prediction,and establish a corresponding model of infiltration,which is the equivalent of soil infiltration process made a prediction. Two methods,the model forecasts a total of 180 minutes infiltration values H₁₈₀,infiltration coefficient b, infiltration index n,so determine the infiltration coefficient of a,the establishment of vegetation suitable for the soil infiltration model,Forecast this vegetation patterns of soil and water conservation benefits.6 The soil infiltration capacity of the soil water retaining is an important indicator of function,and soil properties,soil temperature and moisture content of the soil.Rainfall intensity in certain conditions,the water fully formed into the soil or underground storage runoff,reducing surface runoff.On the other hand,forest measures on the soil properties have improved,and with the increase of age,such a role gradually increased,reflected in the penetration curve shape changes,even the same type of soil, vegetation types because of the impact of soil physical properties there will be quite different. Comparison of different vegetation patterns at the same soil permeability,soil water and soil hydrology of the physical nature of the change,Arundinaria amara forests the largest and second Betula luminifera forests,Bambusa pervariabilis×Dendrocalamopsis oldhami forests the poor.