Study On Soil Anti-erodibility With Different Vegetation Types In Typical Small Watersheds Of North Sichuan

The terrain in the small basin of northern Sichuan is complex and rich in vegetation.Due to the destruction of vegetation and unreasonable allocation by human activities,the soil quality of small watersheds is degraded,and soil erosion is serious.It is particularly urgent and important to study the soil erosion resistance of strong small watersheds.Over the years,soil erosion has been severe in large areas of small watersheds due to man-made damage to forest stands and unreasonable allocation.Therefore,in this paper,five typical vegetation types of SBL mixed forest,BS mixed forest,BM pure forest,JA pure forest,and ZL pure forest were selected as the research objects.17 soil physical corrosion resistance indicators were selected.,Through a combination of outdoor survey and indoor analysis,the corrosion resistance characteristics and particle characteristics of the soil under five planting conditions were studied,and the relationship between the two was analyzed.On this basis,a comprehensive evaluation of the soil erosion effect at the different vegetation conditions in the study area was conducted through the principal component analysis method,with a view to providing a theoretical basis for the rational allocation of vegetation and effective prevention and control of soil erosion in the study area.The main findings are as follows:(1)The soil erosion index of 0-20 cm soil layer of different vegetation types in the study area is as follows:SBL mixed forest(45.3%)> BS mixed forest(33.3%)>BM pure forest(32.0%)>ZL pure forest(25.3%)>JA pure forest(21.3%).In addition,the study found that the content of <0.002 mm clay particles was significantly positively correlated with the soil corrosion resistance index.It shows that the soil texture is better and the erosion resistance of the SBL mixed forests is better than other stands.The soil corrosion resistance index of the 20-40 cm soil layer also showed the same change rule,and the soil corrosion resistance index of the 0-20 cm soil layer was higher than that of the 20-40 cm soil layer.It shows that the 0-20 cm soil layer has stronger soil corrosion resistance.(2)The agglomeration of soil micro-aggregates of different vegetation types in the study area shows that mixed forests are better than pure forests.Comparing the ZL pure forest,the JA pure forest and the BM pure forest,it was found that the reunion status of the BM pure forest was better,and the JA pure forest was the worst.The size of fractal dimension of soil microaggregates in the 0-20 cm soil layer of the five planting types is the highest in the ZL pure forest(2.57),followed by the BM pure forest(2.55)and the JA pure forest(2.54),the SBL mixed forest(2.50)and BS mixed forest are lower(2.46).(3)The soil gradation in different vegetation types of the study area showed that the SBL and the BS mixed forest were the best,the unevenness coefficient(Cc)was greater than 5,and the curvature coefficient(Cu)was between1-3.However,the soils of BM pure forest,JA pure forest,and ZL pure forest soil gradation was poor.The skewness of the 0-20 cm soil layer under the conditions of the five planting types is:ZL pure forest(1.72)> JA pure forest(1.27)>BM pure forest(1.25)> SBL mixed forest(1.02)> BS mixed forest(0.99).In the 20-40 cm soil layer,the skewness also shows the same change law.This study also found that soil skewness and soil erosion index showed a significant negative correlation,and a significant positive correlation with the curvature coefficient.(4)Among the five different vegetation types,the comprehensive score of the corrosion resistance index of the 0-20 cm soil layer from large to small is:SBL mixed forest(0.109)> BS mixed forest(0.051)>BM pure forest(-0.043)> ZL pure forest(-0.055)> JA pure forest(-0.099);the comprehensive erosion resistance score of20-40 cm soil layer is:SBL mixed forest(0.081)> BS mixed forest(0.025)>ZL pure forest(-0.053)>BM pure forest(-0.083)> JA pure forest(-0.137).The soil anti-corrosion effect of SBL mixed forest is the best,and that of JA pure forest is the worst.