| In the present study,five secondary forest types(Coniferous forest,Coniferous broad-leaved mixed forest,Deciduous broad-leaved forest,Deciduous broad-leaved mixed forest,Evergreen and deciduous broad-leaved mixed forest)in Karst area in southwest China were selected.Through the five leaf layer,litter layer and soil layer three nutrient cycle research,from the ecological characteristics of chemometrics,stability characteristics,nutrient use efficiency,nutrient cycling in the region of five forest community types of nutrient adaptability to make analysis and evaluation,the results indicated that:The leaf N:P values of arbor,shrub and herb were 10.65,10.55,11.76,which were less than 14,and the overall performance was limited by N,The deficiency of N element may be the main nutrient limiting the growth of plants in Karst region of Guizhou Province.The N:P value of the nitrogen fixing plant mulberry and Alder is close to 14,which is not limited by N.The changes of C,N,P and stoichiometry of plant leaves in different communities were consistent,The soil N,P content showed a trend of rise after the first reduce;The variation is not obvious in litter layer.The correlations between C、N、P of plants,litter and soil in Karst area.There was no significant correlation between plant and litter(P>0.05);There was a significant negative correlation between N content and N,C:N(P<0.05)in soil.Tree layer of nutrient accumulation of the vegetation layer is up to 77.57%~92.05%,The nutrient accumulation of tree layer was the main producer of organic matter in forest ecosystem,and the nutrient elements accumulated in the tree layer accounted for most of the whole forest stand.The Nutrient utilization coefficient of forest community in kaster area is 0.10~0.44,Circulation coefficient is 0.44~0.60,the highest nutrient resorption efficiency in community of Cupressus funebris had the highest plant nutrient use efficiency and the stability of the community features.The stability intersection points of each community are far from the equilibrium stable points 20/80,the homeostasis indexes HN、HP、HNP of arbor layer under different community types in Karst area is 0.78,1.05,0.78;The stability of the forest communities in the 5 secondary forests was unstable;The homeostasis indexes HN、HP in the order of.Community Ⅰ> Community Ⅱ,Community Ⅲ> Community Ⅳ,CommunityⅤ;In plants,the stability index of stem was the highest,and leaf was the lowest.The plants with high nutrient use efficiency were more competitive,the N,P had the highest nutrient use efficiency in community of Cupressus funebris and Pinus armandii,with an NUEN average of 101.82,NUEP average of 1994.05;The community of Betula luminifera had the lowest,and an average of NUEN,NUEP is 70.20 and 924.62.Nutrient resorption is an adaptation mechanism of plants to nutrient poor environment,which can reflect the degree of nutrient re absorption.the N,P had the highest nutrient resorption efficiency in community of Cupressus funebris and Pinus armandii,with an REN average of 30.76,REP average of 69.12;The community of Betula luminifera had the lowest nutrient resorption efficiency,and an average of REN,REP is 17.71 and 18.39.Ecological stoichiometry,Nitrogen nutrient cycling coefficient,Phosphorus nutrient cycling coefficient,It is important to reveal the mechanism of plant adaptation to nutrient use efficiency and homeostasis indexes,Comprehensive comparison and analysis,the community of Cupressus funebris and Pinus armandii have the highest homeostasis indexes,The ability of plants to utilize nutrients is high,the environment has little effect on it,have a strong ability to adapt to the poor environment,the community of Betula luminifera is lowest. |
