Correlation Between Plant Diversity And Soil Physical And Chemical Properties In Different Degrees Of Rocky Desertification In Western Hunan

In this study,the plant diversity and soil characteristics of different rocky desertification areas in western Hunan were studied.The vegetation composition types and structural characteristics in the study area were investigated and analyzed.The plants were diverse through gray correlation and stepwise regression.Sexual index and soil physical and chemical factors are quantitatively analyzed and related links are sought to provide a basis for the conservation and sustainable use of plant diversity in rocky desertification areas.Main conclusions are as follows:(1)There are fewer arbor species in the study area,and the average vegetation coverage is 66%,mainly shrub herb,and the arbor is mainly distributed in potential and mild rocky desertification areas.There are 30 families,50 genera and 60 species in the shrub ecosystem in the survey area,among which the number of plant species in the potential,mild,moderate,severe and extremely severe rocky desertification plots is 42,39,31,34,28 types respectively.The species and quantity of Rosaceae,Leguminosae,Lonicerae,Compositae and Gramineae in different rocky desertification plots were more,indicating that there were significant differences in the composition and structure of rocky desertification species.(2)As the degree of rocky desertification increasing,the species diversity index(a diversity)shows a downward trend,and the change trend of shrub layer and herb layer is similar,both of which show that the index value decreases with the severity of rocky desertification.The coefficient of differentiation((3 diversity)of different types of rocky desertification community types showed that the difference coefficient between severe and extremely severe rocky desertification areas and other plant communities was larger,indicating the species's components between severe,very severe and other communities are quite different.(3)The changes of various physical indicators in soil factors are as follows:the soil bulk density increases with the deepening of rocky desertification degree,and becomes firmer with the deepening of soil layers;the change of soil porosity decreases with the deepening of rocky desertification,both of which show the potential rocky desertification is biggest and the severe rocky desertification is least;the soil water gradually decreases with the deepening of rocky desertification.The changes of chemical indexes in soil factors are as follows:the soil pH value increases gradually with the deepening of rocky desertification,but the change is not obvious.The acid-base imbalance occurs in the extremely severe rocky desertification degree,which is weakly alkaline;the content of total nitrogen in soil decreases with the deepening of rocky desertification;the order of the soil total phosphorus content in the soil layers of three different depths was the largest in moderate rocky desertification and the least in severe rocky desertification;The variation of the content in three different depth soil layers shows that the rocky desertification is the least,and the variation trend of other rocky desertification degree is different,but the difference is not significant;the effective phosphorus content of the potential rocky desertification degree is significantly higher than other four.The degree of other species was not significant;the effective potassium content in soil showed potential and moderate rocky desertification was significantly higher than that of extremely severe rocky desertification;the change of organic matter content in soil showed from potential to extremely severe rocky desert.Gradual reduction,the law of change is obvious and the magnitude of change is large.(4)Using the stepwise regression analysis method,the soil factors that have great influence on the plant diversity index are capillary water content,saturated water content,field water holding capacity and total porosity.Using the gray correlation analysis method,the soil factors that have great influence on the plant diversity index are soil bulk density,total porosity,saturated water content and capillary water content.Through stepwise regression and grey correlation analysis,the soil factors that have great influence on plant diversity in rocky desertification areas are soil water and soil total porosity.