Study On The Effects Of Different Pinus Tabuliformis Forest Types On Soil Chemical Properties And Microbial In Western Liaoning Province

Western Liaoning is a typical semi-arid area with serious soil erosion.Since the 1950 s,a large area of pure P.tabuliformis forest has been planted.Due to the single tree species and excessive density,this kind of stand gradually has some problems,such as frequent occurrence of diseases and pests,difficult growth of understory vegetation and so on.In 1998,the local forestry authorities carried out a zonal clear cutting of some pure P.tabuliformis forests,which was set along the contour line with a cutting width of 30 m.R.pseudoacacia and A.sibirica were planted in some cutting zones respectively,forming a mixed forest of P.tabuliformis R.pseudoacacia and P.tabuliformis A.sibirica with the original P.tabuliformis reserve zone;The naturally renewed V.negundo in the cutting zone without broad-leaved trees and the original P.tabuliformis reserve zone form a P.tabuliformis V.negundo mixed forest;The natural regeneration of P.tabuliformis in the cutting zone without broad-leaved trees forms a pure P.tabuliformis forest with the original P.tabuliformis reserve zone.Taking pure P.tabuliformis forest,P.tabuliformis A.sibirica mixed forest,P.tabuliformis R.pseudoacacia mixed forest and P.tabuliformis V.negundo mixed forest as the research objects,this study explored the effects of four different types of P.tabuliformis forest on soil chemical properties,soil microbial community structure,diversity and uniformity,and the correlation between soil microbial community structure and soil chemical properties.The results showed that compared with pure P.tabuliformis forest,mixed P.tabuliformis and A.sibirica forest,mixed P.tabuliformis and R.pseudoacacia forest and mixed P.tabuliformis and V.negundo forest could increase the soil p H value,total carbon,total nitrogen,hydrolyzable nitrogen and available potassium in varying degrees.Among them,mixed P.tabuliformis and A.sibirica forest increased the most significantly,with 7.71,20.10 g / kg,1.48 g / kg,108.38 mg / kg and 102.80 mg / kg respectively.Compared with P.tabuliformis pure forest,different types of P.tabuliformis mixed forest stands can improve the Pielou of soil bacteria＿E index,Shannon index,Simpson index and Chao1 index of soil fungi.There are 10 dominant groups of soil bacteria at the phylum level.Ascomycota,Basidiomycota and Mortierellomycota are dominant fungal communities in different P.tabuliformis mixed forests.Different types of P.tabuliformis forest branches enrich different types of soil bacterial and fungal communities.There were significant differences in soil bacterial and fungal communities among pure P.tabuliformis forest,P.tabuliformis A.sibirica mixed forest,P.tabuliformis R.pseudoacacia mixed forest and P.tabuliformis V.negundo mixed forest,with P.tabuliformis and A.sibirica mixed forest changing the structure of soil microbial community significantly.There was an obvious correlation between soil environmental factors and the community structure of bacteria and fungi.Significant differences existed in soil bacterial and fungal communities among P.tabuliformis-A.sibirica mixed forest,P.tabuliformis-R.pseudoacacia mixed forest,P.tabuliformis – V.negundo mixed forest and P.tabuliformis pure forest.Soil environmental factors can significantly affect the bacterial community structure.p H value,total nitrogen,carbon nitrogen ratio,total phosphorus,hydrolyzable nitrogen and available potassium have a great effect on Proteus,blastomonas and Campylobacter.At the level of soil fungi.Mortierella is greatly influenced by total nitrogen and hydrolyzable nitrogen.To sum up,the results reveal the effectiveness of different types of P.tabuliformis mixed forests on soil nutrients,soil microbial diversity and composition,and provide scientific theoretical support for the implementation of sustainable management and management of pure P.tabuliformis forests.Compared with pure P.tabuliformis forest,mixed P.tabuliformis-A.sibirica forest,mixed P.tabuliformis – R.pseudoacacia forest and mixed P.tabuliformis-V.Negundo forest can improve soil p H value,total carbon,total nitrogen,hydrolyzable nitrogen and available potassium in varying degrees;In western Liaoning,the diversity of soil microbial communities,as well as their composition,functional characteristics and structural characteristics of P.tabuliformis mixed forest,P.tabuliformis mixed forest and P.tabuliformis mixed forest are better than those of pure P.tabuliformis forest.