Element Stoichiometry Of Seven Common Woody Plants And Its Association With Habitat Conditions In The Karst Forests Of Maolan

The elemental content of plants is crucial for ecosystem functioning and biogeochemical cycling.Due to the influence of karst landforms,karst ecosystems exhibit unique ecological characteristics.The special and limited distribution of habitats has resulted in distinctive karst forest ecosystems,making research on karst plant ecology particularly significant.Southwest China,including Guizhou province,is a hotspot of biodiversity in karst regions worldwide.Therefore,studying the chemical stoichiometry of plants in Guizhou’s Maolan National Nature Reserve is of great importance for understanding the diversity of plant nutrient strategies and physiological adaptations to climate and soil heterogeneity.In this study,we selected seven common plant species from Maolan National Nature Reserve as research subjects,including two evergreen trees,Quercus glauca and Lindera communis;two evergreen shrubs,Pittosporum glabratum and Pittosporum trigonocarpum;and three deciduous trees,Clausena dunniana,Platycarya longipes,and Carpinus pubescens.We sampled and measured the elemental content of carbon,nitrogen,phosphorus,calcium,and magnesium in plant leaves,branches,and soils,as well as recorded habitat conditions such as topography and landforms.We investigated the interactions between plant-soil elemental content and stoichiometric characteristics,as well as the relationships among plants,soils,and biomass in different habitats.The results revealed that:Quantitative analysis and cluster analysis of plant elemental composition revealed that Lindera communis belongs to the calciphobe plant species,while Clausena dunniana belongs to the calciphile plant species.In terms of different plant functional groups,leaf carbon(C)content follows the order of evergreen trees > evergreen shrubs >deciduous trees,while nitrogen(N),phosphorus(P),and magnesium(Mg)content follows the order of deciduous trees > evergreen trees > evergreen shrubs,and calcium(Ca)content follows the order of deciduous trees >evergreen shrubs > evergreen trees.The aboveground parts of plants have higher leaf C,N,P,and Mg content compared to branches,while Ca content is higher in branches than in leaves.The coefficient of variation of C element in branches and leaves is the lowest,while Ca and Mg show strong variability.The C/N ratio in branches and leaves follows the order of evergreen trees > evergreen shrubs > deciduous trees,and the C/P and N/P ratios in branches and leaves follow the order of deciduous trees >evergreen trees > evergreen shrubs.The Ca/Mg ratio in branches and leaves follows the order of deciduous trees > evergreen shrubs > evergreen trees.All seven study species in this study belong to the P-limited type.By comparing the partial correlations between different control types,it was found that N,shoot Ca,evergreen shrub leaf C and deciduous tree Mg in this study were mainly affected by soil,and leaf P of the three vegetation types were mainly affected by branches.The leaves P,Mg,branches Mg,and deciduous tree C were positively affected by aboveground biomass.Deciduous trees Ca,Mg,and shoot P were negatively affected by aboveground biomass.The environment affected the content of plant elements,and the impact on different living plants was different.Regulation of aboveground biomass of arbor plants can be considered from the elements P and Mg.Soil element content is significantly positively correlated with branch C content,significantly negatively correlated with branch P content,and significantly negatively correlated with leaf Ca and Mg content.Plant life form has the greatest influence on plant stoichiometric characteristics,and slope aspect is significantly negatively correlated with leaf P content and significantly positively correlated with branch N content.The environment affected the content of plant elements,and the impact on different living plants was different.Regulation of aboveground biomass of arbor plants can be considered from the elements P and Mg.The study found that the distribution of the same nutrient elements varies among different plant species and life forms,with Ca and Mg showing the most significant differences.Habitat type has a significant impact on the interactions among plants,soil,and biomass.The correlation between plant elemental content and soil,plant lifeform,and slope aspect is the most significant.This study provides data support and reference for future research on plant stoichiometric characteristics in karst forests.