Plant And Soil Microbial Diversity In Different Vegetation Restoration Stages In Subtropical Region And Their Correlation

To understand the different stages of vegetation restoration of plant and soil microbial diversity characteristics and its correlation,this article adopts the method of spatial sequence instead of time series,in ganzhou city shicheng river source of national natural protection zones for k forest farm as study area,select Remnant forest(CC,vegetation recovery time of 10 a),mixed needle leaf(HJ,vegetation recovery time of 30 a),broad-leaved forest(CS,vegetation recovery time for 100 a)as the research object,represent the degradation of the ecological system for vegetation restoration after the early,middle and late stage,Based on the study of different stands,plant diversity,soil nutrients,litter biomass,fine root biomass and morphology,soil microbial diversity characteristics and their relationships,the following preliminary conclusions were obtained:(1)In the sample plots investigated,there were 22 species of arbor plants in 15families,18 genera,and CS(18 species)>HJ(8 species)>CC(7 species)in different vegetation recovery stages.In the shrub layer,there were 25 species of 22 genera and 17families,with CS(18 species)>HJ(15 species)>CC(13 species)at different vegetation recovery stages.There were 5 families,6 genera and 6 species in the herbaceous layer,and HJ(5 species)>CC(3 species)>CS(2 species)in the same vegetation recovery stage.Plant species richness,Simpson index and shannon-wiener index all increased with the progress of vegetation restoration,while Pielou index did not change significantly.The plant diversity index of CC and HJ changed into shrub>shrub>herbaceous layer and CS was shrub>herbaceous layer.The similarity between HJ and CS was higher(0.55),followed by that between HJ and CC(0.51),and lowest between CC and CS(0.33).(2)The contents of soil organic matter,total nitrogen,available phosphorus and available potassium increased with vegetation restoration,and the contents of total phosphorus and total potassium increased first and then decreased.The change of litter biomass with vegetation recovery stage was HJ(10160kg/hm~2)>CS(8850kg/hm~2)>CC(6470kg/hm~2).The total biomass of fine roots in 0~30cm soil layer was CC(19.61t/hm~2)>HJ(11.63t/hm~2)>CS(7.27t/hm~2),fine roots of trees and shrubs were CS>HJ>CC,and fine roots of herbs were CC(17.24t/hm~2)>HJ(8.37t/hm~2)>CS(0.07t/hm~2).The biomass of fine roots in 0~10cm soil layer was CC(14.31t/hm~2)>HJ(7.73t/hm~2)>CS(4.17t/hm~2),the biomass of fine roots in 10-20cm soil layer was CC(3.16t/hm~2)>HJ(2.25t/hm~2)>CS(1.82t/hm~2),and the biomass of fine roots in 20-30cm soil layer was CC(2.15t/hm~2)>HJ(1.64t/hm~2)>CS(1.28t/hm~2).The specific root length,specific surface area,root length density and root surface area density of fine roots decreased with the vegetation restoration stage.(3)The total number of soil microorganisms did not change significantly with the vegetation recovery stage,and the number of bacteria,actinomycetes,gram-positive bacteria,arbush-root fungi and anaerobic microorganisms basically changed with the vegetation recovery as CS>HJ>CC,while the number of fungi,gram-negative bacteria and eukaryotic microorganisms did not change significantly.Bacteria,actinomycetes and fungi were the fungi with high soil microbial quantity in the three stages of vegetation recovery,and all of them were bacteria>actinomycetes>fungi.The number of soil microorganisms decreases with the depth of soil.There was no significant difference in soil microbial diversity index among different vegetation restoration stages,but there was a slight difference among different soil layers.(4)The plant species richness index was significantly positively correlated with total phosphorus,available phosphorus,tree rootstock and shrub rootstock.It was negatively correlated with total potassium,fine roots and fine root length density,and negatively correlated with total biomass of fine roots,specific root length,specific surface area and density of fine roots.Simpson index was negatively correlated with total biomass of fine roots.Shannon-wiener index was significantly positively correlated with total nitrogen,and was significantly positively correlated with total phosphorus,available phosphorus and arbor root size.It was negatively correlated with total potassium,total arbor fine roots,herb fine roots,and fine root length density,and negatively correlated with specific root length,specific surface area,and density of fine root surface area.The total amount of soil microorganisms,bacteria and actinomyces reached or exceeded significant positive correlation with total phosphorus,available phosphorus,fine roots of trees and shrubs,and reached or exceeded significant negative correlation with total potassium and fine roots of herbs.Soil microbial species richness index was significantly positively correlated with organic matter,and was significantly positively correlated with total nitrogen and available potassium.Simpson index was positively correlated with available potassium.Shannon-wiener index was positively correlated with organic matter and total nitrogen,and positively correlated with rapidly available potassium.(5)Plant species richness index,Shannon-Wiener index and total number of soil microorganisms,bacteria,actinomyces,gram positive bacteria,am fungi,anaerobic microorganism quantity and the bacteria:fungi reached significant or extremely significant correlation,Pielou index and actinomycetes,gram positive bacteria,am fungi quantity is positive correlation,Simpson index and the number of microorganisms and other groups total correlation were not significant;Among the three microbial groups,actinomycetes had the highest correlation with plant diversity.The plant diversity of arbor layer was positively correlated with the total number of soil microorganisms,bacteria,actinomycetes,gram-positive bacteria,number of arbuscles and root fungi,and bacteria.Shannon-wiener index and shannon-wiener index in shrub layer were significantly or very significantly positively correlated with the total number of microorganisms,bacteria,actinomycetes,gram-positive bacteria,arbush-root fungi,anaerobic microorganisms and bacteria.The correlation between herb layer and microbial content was not significant.The correlation between plant diversity and soil microbial diversity was not significant.Species richness index of tree layer was significantly positively correlated with microbial Simpson index,shannon-wiener index of shrub layer was significantly positively correlated with microbial Simpson index,and four diversity indexes of herb layer were significantly negatively correlated with microbial Simpson index and shannon-wiener index.In conclusion,with the progress of vegetation restoration,soil nutrients,litter biomass and plant diversity improved to some extent.Plant diversity and soil microbial diversity is not the simple increase or decrease,and may be associated with a particular stage of forest vegetation species composition,part of the ground vegetation composition form specific litter and root system,which together affect soil microorganisms,therefore,in the production practice in order to maintain the balance and stability of forest ecosystem,should pay attention to in the process of vegetation restoration of vegetation community structure changes.