Research On Soil And Water Conservation Function Of Alpine/Subalpine Forest Soil In Northwest Sichuan

In order to understand the water conservation and soil and water conservation functions of the main forest soil types in the northwest of Sichuan and Sichuan,the method of field investigation and indoor analysis was used to analyze the relationship between cinnamon soil,yellow brown soil and brown soil,Dark brown soil,plateau meadow soil,subalpine meadow soil,and the quantitative and qualitative analysis of six main forest soil types.The physical characteristics and influencing factors of six main forest soils were studied,and the differences of soil and water conservation function indexes of six main forest soils in the region were analyzed comprehensively.At the same time,the main component analysis method was used to evaluate the soil and water conservation function of the main forest soil types in the north of the mountainous and subaqueous mountainous areas in order to improve the soil and soil conservation,water conservation and ecological protection and restoration of the study area.The main findings are as follows:(1)6 different types of soil bulk density increased with the soil layer increased,the order of its size is:brown soil(1.44 g/cm3)>yellow brown soil(1.40 g/cm3)>meadow soil(1.29 g/cm3)>dark brown soil(1.25 g/cm3)>subalpine meadow soil(1.17 g/cm3)>Cinnamon(1.14 g/cm3).(0.88%)was the largest in the dark brown soil(17.28%)and the lowest in the meadow soil(8.87%).The porosity of the capillary porosity was 38.87%,and the dark brown soil(29.95%)was the smallest Porosity of subalpine meadow soil(50.34%)is the largest,and brown soil(44.56%)is the smallest,which indicates that the water storage capacity and permeability of subalpine meadow soil are better than that of brown soil.The average order of sand content in different types of soil is:brown soil>plateau meadow soil>dark brown soil>subalpine meadow soil>yellow brown soil>cinnamon soil;clay content average order:yellow brown soil>subalpine Meadow soil>cinnamon soil>dark brown soil>plateau meadow soil>yellow brown soil,we can see that the highest content of yellow brown soil clay,the best resistance to rainfall erosion.(2)6 different types of soil>5mm dry agglomerate content is yellow brown soil>subalpine meadow soil>cinnamon soil>dark brown soil>brown soil>plateau meadow soil,in the A layer of soil in the proportion of the proportion of:subalpine meadow Soil>yellow brown soil>cinnamon soil>dark brown soil>plateau meadow soil>brown soil,indicating that subalpine meadow soil surface contains large particle aggregates more in soil stability is more advantages.The results showed that the stability of dark brown soil was relatively good,and the stability of dark brown soil was better than that of dark brown soil>brown soil>subalpine meadow soil>yellow brown soil>brown soil>plateau meadow soil,The ability to resist hydraulic erosion is higher than other types of soil.The order of retention of soil aggregates in different types of soil A>2mm was dark brown soil>cinnamon soil>subalpine meadow soil>brown soil>yellow brown soil>plateau meadow soil,indicating that in the surface soil dark brown The soil has the best stability after experiencing rainfall erosion.(3)6 different types of soil air-dried aggregates A layer,MWD is the largest yellow brown soil,the smallest is the brown soil,GMD is the largest subalpine meadow soil,the smallest is brown soil,indicating subalpine meadow soil and yellow brown soil dry body aggregates average diameter agglomeration High,the stability of agglomerates is relatively strong.The MWD and GMD of water-stable aggregates in subalpine meadow and cinnamon soils were relatively large,and the water-stable aggregates of brown soil MWD and GMD are the smallest,indicating that in the surface soil,sub-alpine meadow soil and cinnamon soil aggregates in the water stability is better,not easy to be broken and broken,the soil structure is relatively stable,to maintain strong soil and water capacity.(4)6 different types of soil(101.40 mm),and the order of the maximum water holding capacity of different soil types in the range of 0-100 cm soil layer was as follows:subalpine meadow soil>(101.85 mm)was the largest in the brown soil(118.87 mm),and the soil water was yellowish brown(113.47 mm)(93.62 mm),and the water holding capacity of plateau meadow soil and subalpine meadow soil was the best.(11.24 mm/min)>subalpine meadow soil(9.98 mm/min)>meadow soil(12.22 mm/min)>dark brown soil(11.24 mm/min)(4.13 mm/min)>yellow brown soil(3.23 mm/min)>brown soil(1.30 mm/min).Correlation analysis of soil physical properties and water holding capacity showed that soil bulk density was negatively correlated with organic matter content and maximum water holding capacity,and bulk density was negatively correlated with soil infiltration rate.Soil organic matter content and soil porosity,capillary porosity were significantly positively correlated.There was a significant positive correlation between soil capillary porosity and soil capillary water holding capacity and minimum water holding capacity.(5)Based on the analysis of principal component analysis,six kinds of soil and water conservation functions in the study area were evaluated comprehensively.The results showed that the soil and water conservation functions of six soils in the study area were:subalpine meadow soil>plateau meadow soil>cinnamon soil>yellow brown soil>Dark brown soil>brown soil.The main contributors were the total soil porosity(%),soil infiltration rate mm/min,soil maximum water holding capacity t/hm2,water stable aggregates>2mm content(%),subalpine meadow soil The relative performance of the indicators is relatively good,its water storage capacity is strong,resistance to various types of erosion,especially in the water erosion-based ability is better,soil and water conservation function is relatively good.