| Carbon?C?,Nitrogen?N?and Phosphorus?P?stoichiometry are important characteristics of ecosystem processes and functions,and are of great significance for understanding nutrient cycling in forest ecosystems and improving nutrient utilization efficiency.This study adopts the method of space instead of time,and takes the natural forest of pine massoniana in ganzhou city,Jiangxi province as the research object,the research is based on the investigation and determination of the standard sample plots of young,medium aged,near-mature forests,to analyzed the stoichiometric characteristics of C,N and P in the ecosystem,which provided reference basis for sustainable management measures scientifically of the natural forest of pine massoniana in southern Jiangxi.The main research results and conclusions are as follows:?1?The average contents of C,N and P in all age groups was the largest in leaf,and the contents of C and N in leaf increased first and then decreased,while the contents of P increased with the stand age increased;The C,N contents of shrubs and herbs were significantly higher in the aboveground part than in the underground part?p<0.05?;The C contents of litters showed that the semi-decomposed layer was smaller than the undecomposed layer,while the N and P contents showed that the semi-decomposed layer was larger than the undecomposed layer;The contents of C,N and P in soil decreased gradually with the soil depth deeped,but increased with the stand age increased,among the contents of C and N in 0-10 cm soil layer were significantly higher than those in other soil layers?p<0.05?.The total C contents in the tree layer was larger than that in the understory vegetation layer,while the N and P contents were smaller than that in the understory vegetation layer,the contents of C?N and P in tree layer,understory vegetation and litter layer were all higher than that in soil layer,and the overall contents was medium low to very low in the soil layer.?2?The C:N of the tree layer showed that the trunk was the largest and the leaf was the smallest,the C:N of the leaf,branches and trunks and the C:P of the leaf and branches all showed trend of decreased first and then increased with the stand age increased,the N:P range of the leaf was 10.78-13.90 in all age groups.Understory vegetation in different components,the C:N and C:P of the shrub leaf in each age group were the smallest,the C:N and C:P of the shrub leaf and the C:N of the overground part of the herb decreased gradually with the stand age increased,the N:P range of the shrub leaf was 7.24-8.88 in all age groups.The C:N and C:P of litters showed that the semi-decomposed layer was smaller than the undecomposed layer,the range of different decompoded layers was 13.3-20.8,the range of P content was higher than 0.5-0.8 g·kg-1.The C:N,C:P of soil showed an deccened with the soil depth deeped,but upward trend with the stand age increased.The growth of trees and shrubs and decomposition of litter were limited by N element to a certain extent.?3?There were significant correlation at all layers of the ecosystem.Among them,there was a significant negative correlation between the C content of the tree layer and the undergrowth layer,and the growth of the vegetation layer was competitive;litters were negatively correlated with C,C:N and C:P of soil as a whole.when the C,N and P contents of litters decrease in the undercomposed layer and increase in the semi-decomposed layer,the soil presents a corresponding increase;the correlation the contents of C,N,P and their stoichiometric ratio in leaf,litter,topsoil?0-10 cm?respectively were better than that between them,the correlation between them were mainly reflected in the P element. |
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