Soil Hydrological Characteristics And Corrosion Resistance Of Different Altitude Gradients In Alpine Mountainous Region Of Western Sichuan

In order to understand the changes of soil hydrological characteristics and corrosion resistance at altitude gradient in the alpine mountainous region of western Sichuan,the soil and litter were quantitatively and qualitatively analyzed by the combination of field investigation sampling and indoor analysis,5 elevation gradients were selected for the mountainous in Kangding,western Sichuan.My paper studies the soil physical properties and the variation of litter water holding in different altitude,and obtains the difference of hydrological characteristics and corrosion resistance of soil in this area.At the same time,the main component analysis method was used to comprehensively evaluate the corrosion resistance of five elevation gradient soil in Zheduoshan,and to provide scientific basis and the oretical support for improving soil water conservation and ecological protection and restoration.The main results are as follows:（1）The mean order of effective interception quantity of litter at different altitude is as follows:4000 m>3400 m>3800 m>4200 m,in which>3600 m litter at elevation 4000 m the highest amount of rainfall,to reduce the ability of rainwater to scour the soil,The effect of protecting soil on reducing surface runoff is better than that of other elevations.The water holdup of litter was increased in logarithmic form with the increase of soaking time,and the bibulous rate decreased exponentially,and the relationship was W=a ln（t）+b,v=at^-b.（2）Soil bulk density increased with soil depth and decreased with elevation.The mean size order of the total porosity is:4000 m（58.88%）>4200 m（56.94%）>3600 m（53.35%）>3800 m（53.21%）>3400 m（52.37%）,relative elevation 4200 m,The soil bulk density and soil porosity of 4000 m are superior to those of other altitudes.The mean value of the clay content is as follows:3600 m>4200 m>4000 m>3400 m>3800 m,the soil 4200m and 3600 m is higher than that at other elevation,and the corrosion resistance is the best;the soil of the elevation stickiness m has relatively large porosity,the soil structure is relatively loose,In favor of water infiltration;（3）In the range of soil 0-20 cm in different altitude,the mean amount of maximum holding water is decreasing with the elevation.There was no obvious change in the amount of capillary water,non capillary pore water holding capacity and soil water holding capacity.The initial infiltration rate and the rate of stabilization are increasing with the elevation,the initial permeability is obviously greater than the rate of stabilization,and the initial infiltration rate of soil in the same soil layer is obviously different,and the infiltration rate and time are power-function relations.The infiltration rate tends to stabilize with time,after which the basic maintenance in a stable infiltration state.（4）At different altitude,the content of organic matter in soil surface is relatively high,and the trend of decreasing with soil depth is obvious.Soil organic matter at different altitudes 0-20 cm soil size order is:3800 m（116.88 g/kg）>4000 m（106.16 g/kg）>4200 m（105.78 g/kg）>3400 m 84.66 g/kg)>3600 m（59.91 g/kg）.The aggregate content of>0.25mm particle size reached more than 80%at different altitude.The stability of soil water in different altitudes showed a decreasing trend of MWD and GMD with the deepening of soil layer,which showed that the stabilization of soil aggregates at different altitudes decreased with the increase of depth.In 0-20 cm soil,D is 3800 m minimum,4200 m value is similar to it,and 3400 m is the smallest;The smallest MWD is the soil at elevation 3400m;The largest GMD is the soil of elevation 3800 m,the soil of the elevation 4200 m is the second,the smallest is the soil of elevation 3400 m.The results show that the stability of the aggregates in the 4200 m and 3800 m is high,the soil structure is stable,it is not easily dispersed and broken under the rain water,the corrosion resistance is good,and the soil aggregates of the elevation 3400 m are relatively stable and prone to erosion.（5）The soil corrosion resistance was evaluated comprehensively by principal component analysis,and the corrosion resistance of soil at different altitude in the area was as follows:4200 m>3800 m>3600 m>4000 m>3400 m.The main contributing factors were dried aggregates>0.25 mm particle size content（%）,water stabilized aggregates>0.25mm particle size content（%）,water stability aggregates MWD.The main contributing factors of 4200 m and 3800 m were better than those of other elevations,while those indexes of 3400 m soil at elevation were the worst.Therefore,this experimental study area elevation 4200 m,3800 m soil corrosion resistance relative study area other elevation soil better,elevation 3400 m soil corrosion resistance is relatively poor.