Variation Of Ecological Stoichiometry Characteristics Of Alpine Grassland Ecosystems On The Qinghai-Tibet Plateau

Ecological stoichiometry integrates ecological problems from different levels,such as individuals,species,populations,communities,and ecosystems,from the perspective of element stoichiometry and element balances.This provides a new approach to the unified theory construction from individuals to ecosystems.The ecological stoichiometry characteristics at the species-community-ecosystem level is a cutting-edge issue in the field of ecological stoichiometry research in recent years.However,the current research focus of ecological stoichiometry is mainly on carbon,nitrogen,and phosphorus elements.The research level mainly covers individual plants and species,with relatively little attention to the ecological chemical stoichiometric characteristics and influencing factors at the community and ecosystem levels.This study selected seven research sites along an environmental gradient in the alpine grassland and alpine meadow of the Qinghai-Tibetan Plateau.Through the combination of field investigation,sampling,and laboratory analysis,the concentration of 12 elements(C,N,K,Ca,Mg,P,Fe,Al,Na,Mn,Cu,and Zn)in plant leaves,roots,and soil samples,as well as the C,N,and P content of soil microbial biomass were obtained.Combining the ecological stoichiometry characteristics at the species level with the plant community structure,the ecological stoichiometry characteristics of various components(plants,soil,and soil microorganisms)of plant species,communities,and ecosystems were elucidated based on changes in environmental factors.The main results of this paper are as follows:1.At the species level,significant differences in the concentration of macroelement and C: N,C: P and N: P exist among different plant functional groups.The concentration of macro-element is higher in dicots plants than that of monocots,while C: N,C: P,and N: P are the opposite.The coefficients of variation of microelement and C: N,C: P,N:P in alpine meadow plants are greater than those in alpine steppe plants.There is a significant linear relationship between most elements in plant leaves and average annual precipitation.Variation of micro-element in plant leaves at the species level is greater than that of macro-element,and is more susceptible to environmental factors.2.At the community level,plant leaves have higher levels of macro-element,while roots have a higher concentration of micro-element.The element variation show a trend of decreasing with the increase of element concentration,and the variation of element concentration in roots is more intense.The concentration of macro-element in plant leaves significantly increases with an increase in annual precipitation,while the concentration of micro-element and such as C: N,C: P,and N:P significantly decreases with an increase in annual precipitation.The trend of changes in root elemental concentration with an increase in annual precipitation is opposite to that of leaves.The regulatory role of environmental factors on the elements in plant organs varies depending on the different physiological functions that these elements play in different organs.3.Among the components of the ecosystem,the concentration of microelement in plants show a significant increase trend with the increase of annual precipitation.Most of the elements in the soil don’t show a significant linear relationship with the average annual precipitation.Soil microbial biomass loads C,P,C: P have a significant linear relationship with the average annual precipitation.Variation of multi-element ecological stoichiometry characteristics of plants and soil affects by geographical conditions and climatic factors.C,P and C: P of soil microbial biomass are comprehensively regulated by geographical conditions,climate and soil.