滇中不同植物群落土壤养分及其计量比的变化特征

为了研究不同植物群落土壤养分的时空动态变化特征及其养分计量比特征，选择滇中高原五种典型植物群落的土壤为研究对象，分析了旱、雨季不同营养元素及其计量比在土壤不同深度中的分布特征，并应用灰色关联分析探讨了不同群落的土壤综合肥力及其改良效应。结果表明：（1）在空间尺度上，土壤全氮、碱解氮、有效磷、速效钾和有机质含量随土壤深度增加而降低，全钾含量则随土壤深度增加而增加，而磷含量在土壤剖面中相对保持稳定；除全钾含量外，植物群落对上层土壤的改良效益较高，导致土壤表层土壤养分明显高于中下层；（2）在时间尺度上，除常绿阔叶林雨季肥力略有下降外，其它4种群落雨季的综合肥力均比旱季有所增加。总体看来，常绿阔叶林对土壤养分的影响改良效益最高，而云南松林对土壤养分的改良效益最低；（3）不同植物群落上层土壤C:N、C:P和N:P总体上高于中层与下层土壤，雨季植物群落除桉树林外土壤C:N小于旱季，雨季土壤C:P、N:P总体上高于旱季；土壤养分化学计量比结果表明土壤氮、磷养分是限制植物群落发展的主要限制因子。因此，从不同群落对土壤养分的影响及其生态水文过程上差异的角度出发，建议在滇中脆弱区的生态修复过程中，尽量控制桉树林的种植面积，并对云南松林进行抚育增加阔叶树种的比例，以此增加植物群落对土壤养分的改善效益，进而减少水土流失的风险。为当地树种的选择，从土壤养分变化的角度提供一定的参考。

Changes of Soil Nutrients and Stoichiometric Characteristics Under Different Vegetation Communities in Central Yunnan Province

In order to study the spatial and temporal dynamics of soil nutrients in different plant communities and their nutrient measurement ratio characteristics. The soil of five typical plant communities in the central Yunnan plateau was selected as the research objects. The distribution characteristics of different nutrient elements and their measurement ratios in different depths of soil in dry and rainy seasons were analyzed. The comprehensive soil fertility and its improvement effects of different communities were discussed by means of grey correlation analysis. The results showed that: (1) On the spatial scale, the contents of total nitrogen, alkali-hydrolyzed nitrogen, available phosphorus, available potassium and organic matter decreased with the increase of soil depth, while the contents of total potassium increased with the increase of soil depth and the content of phosphorus remained relatively stable in the soil profile; besides total potassium content, the plant community had a higher effect on the improvement of upper soil, resulting in that the nutrients in the surface soil is higher than the middle and lower strata obviously. (2) On the time scale, except that the fertility of evergreen broad-leaved forest decreased slightly in rainy season, the comprehensive fertility of the other four communities increased in rainy season compared with that in dry season. Generally speaking, the beneficial effect of evergreen broad-leaved forest on soil nutrients was the highest, while the beneficial effect of Yunnan pine forest on soil nutrients was the lowest. (3) C:N, C:P and N:P in upper soil of different plant communities were higher than those in middle and lower soil, C:N in rainy season was lower than that in dry season except for Eucalyptus forest, C:P and N:P in rainy season were generally higher than that in dry season. The results of chemometric ratio of soil nutrition differentiation showed that soil phosphorus and nutrients were the main limiting factors for the development of plant communities. Therefore, considering the effects of different communities on soil nutrients and their differences in eco-hydrological processes, it is suggested that in the process of ecological restoration in fragile areas of central Yunnan, the planting area of Eucalyptus should be controlled as far as possible, and the proportion of broad-leaved trees should be increased by tending Pinus yunnanensis forests, so as to increase the improvement benefits of plant communities on soil nutrients and reduce the risk of soil and water losses.Providing some reference for the selection of local tree species from the perspective of soil nutrient changes.