Relationship Between Community Diversity And Productivity And Influencing Factors In Phoebe Bournei Natural Forest

Productivity and biodiversity are the key indicators for services and functions of ecosystem.The influences of biodiversity on ecosystem productivity globally and regionally and its mechanisms are a key focus for ecologists.Phoebe bournei,a rare wild tree species,is difficult to regenerate naturally.To elucidate the connection between the diversity and productivity of the Phoebe bournei community and the influencing factors within a natural forest,we selected the natural forest of Nanmuchong in Mingyueshan Forest Farm,Jiangxi Province as our research site.Spanning four consecutive years from 2018 to 2021,we undertook observational studies,focusing on the fluctuations in species composition and the notable changes in the natural forest community at different regeneration stages of the Phoebe bournei community.Our examination encompassed species diversity,structural diversity,productivity attributes,alongside environmental factors such as soil nutrients,enzyme activity,and microbial diversity.To decode the relationship between biodiversity and productivity,we deployed linear regression analysis,along with correlation and redundancy analysis to discern the influential factors.The salient conclusions drawn from this research are as follows:(1)Throughout the renewal process from the seedling stage to maturity,the dominance of Phoebe bournei within the community progressively strengthens,indicating superior competitiveness compared to other species.Phoebe bourneis value proves to be pivotal at each renewal phase,optimizing resource utilization for growth,renewal,and consequent productivity.In the latter stages of renewal,Phoebe bournei firmly establishes itself as the cornerstone species within the community.This study finds the renewal process of Phoebe bournei analogous to an invasive procedure.Initially,community species,structural diversity,and biomass have an increase,followed by a decrease during regeneration,correlating with tree growth and interspecific competition.As the renewal process advances,the biomass,productivity,and representation of Phoebe bournei within the community significantly increase,gradually marking it as the primary contributing species to community biomass and productivity.(2)The renewal process of Phoebe bournei markedly transforms soil nutrients,microbial composition,and enzymatic activities.An appreciable increase in soil moisture content and phosphorus nutrient availability was observed during the regeneration process.Plant growth was principally constrained by soil nitrogen content,with the restrictive effect intensifying as regeneration progressed.Enzymatic activities within the Phoebe bournei natural forest were notably reduced.Dominant soil bacteria groups facilitated Phoebe bourneis expanding dominance within the community by degrading plant residues and suppressing pathogen proliferation.Similarly,dominant soil fungi groups supported bourneis dominance in the community by fostering mycorrhizal formation and obtaining soil nutrient elements.The Shannon diversity index of soil bacteria showed a significant increase during the regeneration process,indicating that soil bacterial diversity was significantly higher than that of the soil fungi community.(3)Aboveground and belowground biodiversity jointly regulate the productivity of the plant community within the Phoebe bournei natural forest.There is a considerable positive association between community diversity and biomass,as well as between soil microbial diversity and productivity.Soil carbon to phosphorus(C/P)ratio,nitrogen to phosphorus(N/P)ratio,and the availability of N/P nutrients emerged as the principal environmental factors influencing the species and structural diversity within the Phoebe bournei natural forest.Community diversity displays a positive correlation with soil nutrients,suggesting that soil environmental factors could positively impact productivity via community diversity.In conclusion,this paper has explored the relationship between community diversity and productivity,as well as the influencing factors,through an extended observation and study of the natural regeneration community of bournei over four consecutive years.As community diversity increased during the regeneration process,so did the community biomass.Community productivity demonstrates a substantial positive correlation with soil microorganisms.The availability of soil nitrogen and phosphorus nutrients,as well as the carbon to phosphorus ratio,surfaced as the key factors affecting community diversity and productivity.The biodiversity found both aboveground and belowground collectively regulated the plant community’s biomass and productivity,with soil environmental factors exerting either direct or indirect positive influences on community diversity and productivity.