Spatial Variation In Nutrient Of Dominant Plant And Ecological Stoichiometry From Laohu Gou Of Qilian Mountain

Although the spatial patterns of plant nutrient and ecological stoichiometry has been widely studied at the species level in many fields of plant ecology,few study focused on the variation of ecological stoichiometry with altitude gradient. Three hundred twenty samples of plants and thirty soil samples had been collected from five different altitude gradients in Laohu Gou of Qilian Mountain.To clarify (1) the spatial characteristic of SOM,STN,STP,SAN,SAP content and stoichiometry along various altitude gradients in the study area;(2) the distribution pattern of TC,TN,TP and stoichiometry of leaf and root along various altitude gradients in the study area;(3) to determine the factor of nutrient limitation. The results were followed:1The elevation changes of leaf P, C:P and N:P were significant. There was no changes in leaf C,N and C:N ratio. This explained that each species has its own strategies in response to nutrient acquisition.The content of leaf C was positive correlated to leaf N significantly, the content of leaf N was high positive correlated to leaf P significantly, the content of leaf N was high positive correlated to leaf N:P significantly.This showed that N and P were influenced mutually and coupled greatly with each other in the processes of plant growth and metabolic.2The elevation changes of root C, P and C:P were significant. There was no changes in root N, C:N and N:P ratio. The content of root N was high positive correlated to root P significantly, the content of root N was high positive correlated to root N:P, N and P had better goodness of fit about altitude gradient.this showed that there was coupled about N and P in the growth and development of root.3There was significant changes on the content of SOM, STN, SAN, SAP and N:P ratio along various altitude gradient,but no TP. This explained that soil biogeochemical cycle was affected by a variety of factors.4There was no correlation between nutrient content and stoichiometry of root and soil nutrient content, this reflected that regardless of eutrophication or oligotrophic in the growth environment,plant roots had its own nutrient use strategies and adaptation mechanisms to the soil environment. There was high positive correlation between leaf P and root P significantly, leaf P was high positive correlated to root P significantly. This showed that there was integrity in the growth and metabolic processes of plant, and followed certain regulation in the process of nutrients distribution of leaf and root.5Leaf N:P ratio was15.20in the study area, it was between14and16. This explained that the productivity of vegetation community was N-and P-limited in the study area. The C:N:P of root was301.4:8.4:1in the study area, there was large difference from the results of other studies, the reason was needed to be explored.