Soil Ecological Stoichiometry Characteristics And Microbioal Diversity At Different Elevation In Lu Mountain

Ecological stoichiometry is a tool for studying the coupling and balance of various elements(mainly carbon,nitrogen,and phosphorus)that are required by living organisms and can affect ecosystem productivity and nutrient cycles.Soil biodiversity is considered to be a reliable indicator of soil health and quality,and it plays a key role in regulating ecosystem processes and functions.Environmental differences caused by elevation gradient,such as temperature,water content and vegetation type,lead to changes in soil physicochemical properties of alpine forest ecosystem,thereby affecting soil microbial biomass,soil enzyme activities and microbial diversity.In this paper,soil samples were collected along the elevation gradient on Lu Mountain in Jiujiang City,Jiangxi Province,East China as the research object.By measuring soil nutrients,microbial biomass,enzyme activity and microbial diversity,we first reveal the variation of soil nutrients,microbial biomass,enzyme activity and microbial diversity along the altitude gradient,and then explore the relationship of soil nutrients,microbial biomass and soil enzyme stoichiometry and their impact on soil microbial diversity.It can provide a theoretical basis for improving the soil fertility and productivity of the Lu Mountain forest ecosystem and formulating scientific forest management strategies.The main results are as follows:(1)The physicochemical properties of soil at diverse altitudes were significantly different.The elevation gradient(EG),total carbon(TC),and p H were all significantly correlated with the stoichiometric ratio of soil carbon,nitrogen,and phosphorus(C : N,C : P,N : P).It showed that EG and p H were the main factors affecting the distribution of soil nutrients in Lu Mountain.(2)Microbial biomass carbon,nitrogen,and phosphorus(MBC,MBN,MBP)in soils at diverse altitudes were significantly different.MBC : MBN had significant correlation with TC,TP,C : N,C : P,N : P,which implied that the soil biomass measurement ratio was in an unstable state and has high plasticity.(3)The altitude significantly affected the activities of four soil enzymes: β-D-glucosidase(BG),N-acetyl-glucosaminidase(NAG),leucine aminopeptidase(LAP)and acid phosphatase(AP).From Redundancy Analysis(RDA)and Variance Partitioning Analysis(VPA),soil abiotic factors(39.2%)had greater influence on soil enzyme stoichiometric ratio than biotic factors(17.2%).EG was the key abiotic factor leading to the change of soil enzyme activity and its stoichiometric ratio.At the same time,vector analysis showed that soil microbes were restricted by N below 1065 m,and P restricted above 1222 m.(4)The microbial α-diversity based on Shannon index and Simpson index was significantly different in altitude gradient.The Shannon index and Simpson index of bacteria and fungi were significantly correlated with C : N,C : P,and N : P,except for the Simpson index of bacteria.At the same time,redundancy analysis showed that C : N,C : P,N : P,MBC : MBP,MBC : MBN,and MBN : MBP were important factors influencing the composition of the Lu Mountain soil microbial community.This study shows that EG,TC,and p H were the main factors affecting the stoichiometric ratio of the soil in Lu Mountain,the growth of microorganisms in the soil was mainly limited by N,and abiotic factors were the main factors affecting the changes in soil enzyme stoichiometric ratio at different altitudes.At the same time,the measurement ratio of soil and microbial biomass was an important factor that led to changes in soil microbial biodiversity and community composition.