| As one of the important terrestrial ecosystems,forests involve many complex ecological processes,among which plant leaves,litter,and soil are important components that make up the forest ecosystem.Due to its unique and fragile habitat,karst landforms differ from normal landforms in various aspects such as vegetation types,community composition,and community succession.This study takes Guiyang City,one of the karst landforms concentrated areas in the southwest region,as a representative.In 8 districts and counties,12 karst forests of 4 categories were selected as the study area,with a total of 41 plots set up to study the organic carbon(C)of plant leaves,litter,and soil in karst forests The nutrient content characteristics of total nitrogen(N),total phosphorus(P),total magnesium(Mg),total potassium(K),and total calcium(Ca)are analyzed,and the flow patterns of these nutrients are analyzed.This provides a theoretical basis for revealing nutrient limiting factors,cycling patterns,and plant adaptation strategies in forest ecosystems in karst areas,and provides scientific basis for plant resource protection and soil desertification prevention and control in karst forests.The research results are as follows:(1)The growth of karst forest plants in Guiyang City is jointly restricted by N and P,and there are differences in C,N,and P among different types of forest plants.Moreover,forests with stronger human interference have lower C,N,and P,weaker plant competitiveness and defense against resources,lower decomposition rate of litter,and less nutrient return;The overall N/P shows a decreasing trend,and all are less than 25,indicating that the decomposition of litter in vegetation communities in karst areas is less limited by P;The decomposition rate of soil organic matter is slightly higher than that of the world,and there is little difference compared to the national and southwestern regions;The effectiveness of soil for P is relatively low,and it is even lower in forests with strong disturbances.(2)The correlation analysis of the stoichiometric characteristics of plant leaf litter soil continuum shows that there is a significant correlation(P<0.05)between the nutrient content of different groups of plant leaves,litter,and soil.The N and P content in plant leaves,as well as C/N,C/P,and N/P,significantly affect the changes in most nutrient content in soil.Among them,the correlation between C/N in plant leaves and Mg content in soil is extremely significant(P<0.001),And the correlation coefficient is the highest.Overall,there is a good correlation between plant leaves and nutrient content in the soil.(3)In terms of nutrient utilization rate,the karst forest plants in Guiyang city have the characteristics of high N utilization rate and low P utilization rate as a whole.In addition,according to the results of this study,in different types of forests,the utilization efficiency of N and P nutrients by plants in areas with strong interference such as forest parks and scenic spots shows an upward trend,strengthening the metabolic process to maintain normal levels of plant homeostasis and compensate for the negative impact of external environmental changes;In terms of reabsorption,the ability of karst plants in Guiyang to reabsorb P is higher than that of N,which to some extent compensates for the severe P deficiency of plants in karst areas.(4)The analysis of the internal stability characteristics of plant leaves in Guiyang shows that different types of karst forest plants in Guiyang have different strategies for the storage and absorption of C element.The stability of C element is weaker than that in old-growth forest and karst canyon plants,while the influence of soil on plant C in forest parks and scenic spots is very weak.In addition,overall,the internal stability of N element in Guiyang is worse than that of P element. |
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