Correlation Between Soil Quality And Understory Plant Diversity In Different Types Of Non-profit Forest

The Changsha Ecological Public Welfare Forest plays an important role in maintaining and improving the ecological environment of Changsha and maintaining ecological balance,The total value of various ecological benefits has reached 2.041 billion yuan,it is very important to promote the sustainable development of ecological public welfare forests in Changsha.Soil is the carrier of ecological public welfare forests,The process of vegetation growth succession in ecological public welfare forests is the process of mutual influence and interaction between plants and soil.This article investigated and maked a scientific evaluation of the soil quality status of ecological public welfare forests in Changsha,aiming to further understand the growth and protection of ecological public welfare forests in Changsha,and promote the sustainable and healthy development of ecological public welfare forests in Changsha,with a view to giving play to the public welfare of Changsha The best ecological and social benefits of forest.This article toke ecological public welfare forests in the six districts of Changsha as the research object,and is divided into broad-leaved pure forest(M1),coniferous pure forest(M2),broad-leaved mixed forest(M3),coniferous mixed forest(M4),and coniferous-broad mixed forest(M5),6 types of secondary forests(M6),a total of 54 fixed standard plots were set up,vegetation surveys of tree layer,shrub layer and herb layer were carried out,and the plant diversity index of each layer of the plot was calculated.At the same time,mixed soil samples were collected at each standard site to determine the physical,chemical and biological properties of the soil.Use single factor analysis of variance(ANOVA)to determine the significant differences in soil properties,? and ? diversity indices of the shrub layer and herb layer between different vegetation types;use redundancy analysis to determine the correlation between soil biological indicators and soil physical and chemical indicators;Then through factor analysis and discriminant analysis,construct and verify the revised minimum data set,use the SOI model to calculate the soil quality index;and finally use canonical correlation analysis to determine the relationship between soil properties and understory plant diversity.The main research conclusions are as follows:(1)Principal component analysis and correlation analysis of the soil physical,chemical and biological properties of the ecological public welfare forest in Changsha City,and finally select soil bulk density,organic matter,total nitrogen,total potassium,available calcium,microbial biomass nitrogen,microbes A total of 9 indicators,biomass phosphorus,invertase and phosphatase,constitute the revised minimum data set.Using discriminant analysis to verify the revised minimum data set,the results show that the classification results of the sample points using the discriminant function based on the revised minimum data set are similar to the original situation,and the overall correct judgment rate has reached 84%,of which the coniferous broad-leaved mixed forest and the secondary forest are correct The rate reached 100%,indicating that the selected indicators are representative and can comprehensively and truly reflect the soil quality status.In the future soil quality evaluation process of ecological public welfare forests in Changsha City,the minimum data set can be revised to reduce the work.(2)The soil quality calculated based on the revised minimum data set and soil quality index method is:coniferous and broad-leaved mixed forest>secondary forest>broad-leaved pure forest>broad-leaved mixed forest>coniferous mixed forest>coniferous pure forest.The soil quality is divided into ??? grades.The samples of broad-leaved pure forests are all at grade ?;the 15 sample plots of coniferous pure forests are all at grade?except for 3 at grade ?;the broad-leaved mixed forests are at grade ?;One plot is at level ?,six at level ?,and four at level ?;two coniferous mixed forests are at level ?,one is at level ?,and the other three are at level ?;10 coniferous and broad-leaved mixed forests Among the plots,2 are in Grade ?,4 in Grade ? and 4 in Grade ?;6 plots in secondary forest,2 in Grade V,and the remaining four in Grade ?.The overall soil quality is low.The soil quality of pure coniferous forests and mixed coniferous forests is very low.It is necessary to improve soil quality in time to ensure the sustainable and healthy development of ecological public welfare forests.(3)Most of the public welfare forests of different forest types have significant differences in soil physical and chemical properties.Overall,the soil physical and chemical properties of mixed forests are better than pure forests,and the broad-leaved forests are better than coniferous forests.The bulk density differs most in physical properties.The soil bulk density of pure coniferous forest is 55.23%higher than that of secondary forest.The change trend of capillary porosity is opposite to the soil bulk density.Although there is no significant difference in organic matter in chemical properties(p=0.073),the gap between the groups is still obvious.The soil organic matter content of coniferous and broad-leaved mixed forests is 48.14%higher than that of pure coniferous forests.The soil trace elements in all standard lands are in a state of extreme lack.In the process of improving soil properties,attention should be paid to the input of soil trace elements.(4)There are significant differences in all soil biological properties of public welfare forests of different forest types.The changing trends of soil enzymes and soil microbial biomass carbon,nitrogen,and phosphorus are very similar to soil physical and chemical properties,and secondary forests,broad-leaved mixed forests,and conifer-broad mixed forests always perform better.The results of redundant analysis also show that soil biological properties are closely related to soil physical and chemical properties,especially a significant negative correlation with soil bulk density and a positive correlation with soil organic matter.(5)Among the six forest types,the difference in shrub layer plant diversity is more obvious.The shrub layer plant diversity in pure forest is lower,and the shrub layer plant diversity in coniferous and broad-leaved mixed forest and secondary forest is higher and the species composition tends to be higher stable.There is no significant difference in the plant diversity index of the herb layer,and the species richness of all herb layers is very low.Through typical correlation analysis,the plant diversity of the shrub layer and the herb layer of the public welfare forest has an obvious effect on the soil properties.The conclusions drawn are consistent.When improving the soil quality of coniferous forests and pure forests,it is possible to increase soil nutrient input and improve soil properties and soil quality by increasing the diversity of understory plants.