Soil-leaf Ecological Stoichiometric Characteristics of Different Vegetation Types in the Karst Area of Northwest Yunnan

In order to support the selection of vegetation in the ecologically fragile karst region of Northwestern Yunnan when carrying out ecological management, soil and leaf samples were systematically collected from different types of forests (three types of natural forests, two types of plantation forests and a shrub forest), and analyzed for organic carbon, total nitrogen and total phosphorus, finally, multivariate statistical analysis were comprehensively applied to study the ecological stoichiometric characteristics and correlations of soils and leaves in the Karst region of Northwest Yunnan. The results show that: (1) Natural forest communities have higher soil organic carbon, total nitrogen and total phosphorus contents than plantation and shrub forests, and have slower decomposition rates and soil nitrogen mineralization rates and higher phosphorus effectiveness, in the entire karst region of Northwestern Yunnan, the soil is N-constrained. (2) Based on the leaf organic carbon, total nitrogen and total phosphorus and stoichiometric characteristics of the region, it was shown that the Juniperus squamata in planted forests had the slowest growth rate, while several other vegetation types showed little difference in growth rate. Natural, planted and shrub forest leaves are all N-limited. (3) Soil stoichiometric characteristics in the karst region of Northwestern Yunnan are not directly determined by vegetation leaves, and the correlation between the two is weak. This is related to the fact that soils in the study area are shallow and plant roots move through weathered rocks to take up excess elements. (4) Therefore, natural restoration should be considered as the mainstay of ecological management in the future, Cupressus duclouxiana, J. squamata grown in captivity are not as effective as they could be. If artificial restoration is required, it is recommended to change the tree species or apply additional organic fertilizer as appropriate.