【作者】 胡忠良；

【导师】 潘根兴；

【作者基本信息】 南京农业大学 ， 土壤学， 2009， 硕士

【摘要】 中国西南喀斯特是受地质条件严重制约的特殊的生态系统,该地区的生态治理和恢复是当今生态学界研究的热点之一。土壤是生态系统内最重要的养分和水分资源的调控者,在维持和稳定生态系统结构和功能的过程中发挥核心作用。研究植被因素对土壤养分含量与空间分布的影响及土壤养分循环中的微生物过程,可为喀斯特生态恢复和治理提供科学理论依据。本文以贵州中部喀斯特生态系统不同植被条件下的土壤为研究对象,分析了植被因素对土壤厚度、碳、氮、磷养分元素含量、空间分布及与之相关的微生物功能特点的影响,主要研究结论如下：(1)不同植被下土壤厚度变化特点表现为：乔木林演替为灌木林后,土壤厚度并未发生显著变化,由于植被类型和覆盖率的变化,灌草丛下土壤厚度较灌木林显著降低；(2)各养分元素在不同植被下表现为：土壤有机碳、全量氮、磷养分含量变化表现为：乔木林>灌木林≈灌草丛；有效态养分的变化表现为：乔木林>灌木林>灌草丛。显示有效态养分变化对植被演替的响应较全量养分更灵敏；土壤养分空间变异大,灌木林系统下的土壤养分空间变异性显著高于乔木林和灌草丛；土壤磷素尤其是有效态磷素在各系统中表现出含量低且空间变异性大的特点；因子分析的结果显示：土壤有机质和土壤全氮属同一因子,有效养分及全磷因素归一因子,碳素和氮素间关系紧密且受植被显著影响,有效态养分的变化主要受土壤生化活性的影响；(3)在微生物量上,不同植被条件下的土壤微生物碳量不存在显著差异,但土壤微生物氮量及土壤微生物量碳氮比在各系统间差异显著,显示在土壤微生物群落区系在不同植被下发生显著变化；(4)不同土壤酶活性对于植被演替的响应程度不同,植被条件改变后土壤蔗糖酶活性变化最为显著,而脲酶表现为乔木林>灌木林≈灌草丛,碱性磷酸酶表现为乔木林>灌草丛>灌木林,在低磷条件下,植物和微生物可能通过提高磷酸酶活性的方式以适应之。总之,由以上结果可以发现,土壤养分含量在植被演替后不断下降,特别是有效养分含量下降较全量养分含量更为显著,土壤养分的空间异质性随之增加,而同时,与土壤养分含量与活性相关的土壤微生物区系和土壤酶活性也发生改变。在植被条件改变后,土壤养分循环过程发生改变,生态系统对土壤养分的调控能力下降。更多还原

【Abstract】 Karst ecosystem of southwest China is seriously constrained by geological settings. The restoration and reconstruction of degraded karst ecosystem has been one of the most focused problems of modern ecology. Soil is considered as the main nutrient and water provider, which plays key role in maintaining and stabilizing the structure and functions of ecosystem. Based on understanding the effect of vegetation on the quantity and distribution of soil nutrient, and the microbial process will provide us scientific and practice theory in karst ecosystem reconstructing. In this study, based on the soil under three different karst vegetations in central Guizhou province, the effect of vegetation on the contents and distribution of soil depth, carbon, nitrogen and phosphorus, and microbial functions were analyzed.The following conclusions were drawn from the analysis:(1) By comparing the soil depth under three secession sequences, it was found that three has no significantly different between forest and shrubs, but soil depth decreased significantly when the shrub degraded to grassland.(2) Under three different vegetation conditions, Soil available nutrient content followed such order:forest>shrub>grassland. At the same time, the total nutrient content followed the order:forest> shrub≈grassland. Available nutrient was more sensitive to the vegetation succession than the total nutrient. The highest spatial heterogeneity of soil nutrient pools was found under shrub associated with soil P. Moreover, according to the factor analyze result, we found that soil organic carbon and total nitrogen belong to one factor, soil available nutrient and total phosphorus belong to the other factor; carbon and nitrogen closely related in ecosystem which mainly affected by plant, soil biochemical activities affected the content of available nutrient significantly.(3) The soil micro biomass carbon had no significant difference among three different vegetations, while the soil micro biomass nitrogen changed significantly. Soil micro biomass carbon/nitrogen changed significantly indicated that the micro flora changed accordingly with the vegetation conditions.(4) The response of each type of soil enzyme activity to the change of vegetation was different. Among them, invertase was found the most sensitive. Urease activity followed the order:forest>shrub≈grassland. But alkaline phosphatase activity followed the order: forest> grassland>shrub, which showed that plant and microbial may increase phosphatase activity to adapt to the low phosphorus environment.As a whole, we can find that soil nutrient content decreased with the vegetation succession, especially for the available nutrient, and the soil nutrient spatial heterogeneity became higher as well. The micro-flora and enzyme related with the nutrient cycle changed indicated that when the vegetation changed, the process of soil nutrient cycle and the ability of regulation and control over soil nutrient of ecosystem decreased.更多还原