喀斯特典型生态系统土壤胞外酶活性及其影响因素

发布时间：2018-02-27 00:21

本文关键词： 喀斯特土壤酶活性土壤理化属性树种不同土地利用方式　出处：《广西师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：土壤有机质分解是大气二氧化碳(CO2)的主要来源,也是生态系统内部碳、氮、磷等物质循环的关键步骤。土壤中的有机质需要经过胞外酶(除非特别说明,以下所指的土壤酶均指胞外酶)的解聚作用(Depolymerization)生成小分子或单分子有机物后,微生物才能直接吸收利用,土壤碳、氮、磷等物质循环的后续过程才能顺利进行。正因为如此,由土壤酶主导的大分子有机质解聚这一步骤往往成为土壤碳、氮、磷循环的限制性环节。可见,土壤酶在生态系统物质循环和能量流动中扮演着重要角色,深入认识土壤酶活性对于理解生态系统碳、氮、磷元素生物地球化学循环过程具有重要意义。喀斯特生态系统是地球表层系统的重要组成部分。由于其地质背景的特殊性,喀斯特生态系统的生物地化循环存在特异性,这可能导致土壤胞外酶活性及其主控因素有别于其它生态系统。然而,目前对西南喀斯特山区典型生态系统土壤胞外酶活性及其主控因素的研究非常缺乏。本研究以典型喀斯特生态系统为对象,首先研究了不同植被恢复阶段(农田、草地、灌丛、次生林)土壤碳、氮和磷转化相关胞外酶活性及其主控因素;在此基础上,对典型喀斯特与相邻非喀斯特森林土壤胞外酶活性开展了对比研究。研究得到的主要结论如下:(1)喀斯特山区植被恢复过程中,土壤水解酶(参与活性碳库的分解)和氧化酶活性(参与惰性碳库的分解)的响应结果显示,随着植被恢复,土壤水解酶(即β-葡糖苷酶、α-纤维素酶和β-木糖苷酶)活性不断增加(即次生林灌丛草地农田),土壤氧化酶(过氧化物酶)活性无明显变化。喀斯特地区退耕后,随着植被恢复,氮循环酶(即亮氨酸氨基肽酶、几丁质酶、脲酶、蛋白酶)活性不断增加。相关性分析发现脲酶和蛋白酶与有机质和全氮极显著相关。磷酸酶的活性与土壤pH和交换性镁离子有相关性,而与其他理化性质无明显相关性,综合分析表明:喀斯特地区土壤交换性镁离子对酸性磷酸酶具有正效应,而对碱性磷酸酶无显著效应;土壤理化指标与磷酸酶活性相关性分析发现,喀斯特地区土壤磷酸酶除受pH以及交换性镁离子的影响外,与其它所测理化指标均无显著相关性。(2)喀斯特与非喀斯特地区酶活性对比研究发现,两个地区属于不同的土壤类型,喀斯特地区(碱性的钙质土壤)酶活性普遍高于非喀斯特地区(酸性的红壤),除了酸性磷酸酶和几丁质酶活性外,其它所测的八种酶活性在喀斯特地区均显著大于非喀斯特地区,两种土壤类型的酶活性受控因子也不同,喀斯特地区受控因子较非喀斯特地区影响因子更集中。(3)通过方差分解的方法分析了树种、土壤理化性质和土壤类型三组解释变量对土壤酶活性的相对贡献,结果显示:三组解释变量总共解释了土壤酶活性变异的62.6%。其中,土壤理化性质解释了土壤酶活性变异的58.2%,土壤类型解释了土壤酶活性变异的38.7%,树种因子解释了土壤酶活性变异的27.8%。三组变量存在交互作用,三者共同解释的部分为17.8%。当剔除了两两间共同解释部分后,土壤理化性质净解释了土壤酶活性变异的23.4%,土壤类型净解释了土壤酶活性变异的3.9%,树种因子净解释了土壤酶活性变异的0.9%。
[Abstract]:Soil organic matter decomposition is atmospheric carbon dioxide (CO2) is the main source of internal ecosystem carbon, nitrogen, phosphorus and other key steps of material circulation. The organic matter in the soil by extracellular enzymes (enzyme unless otherwise specified, the following refers to the mean extracellular solution) poly (Depolymerization) generates a small role single molecule or molecular organic matter, microbes can be directly absorbed by soil carbon, nitrogen, phosphorus and other substances to the subsequent process of circulating smoothly. Because of this, the steps of macromolecular organic matter was dominated by soil enzymes often become soil carbon, nitrogen, phosphorus cycle restriction factors. Therefore, soil enzyme plays an important role in the material cycle and energy flow in ecosystem, in-depth understanding of soil enzyme activity to the understanding of ecosystem carbon, nitrogen, phosphorus plays an important role in the biogeochemical cycle of Karst ecosystem. The system is an important part of the earth surface system. Because of its special geological background, Karst ecosystem biogeochemical cycles in the presence of specific, which may lead to soil extracellular enzyme activity and its main controlling factors are different from other ecosystems. However, the current research on the southwest Karst area of typical soil ecological system and its extracellular enzyme activity the main control factors is lacking. In this study, the typical Karst ecological system as the object, firstly study the different vegetation restoration stages (farmland, grassland, shrub, secondary forest) of soil carbon, nitrogen and phosphorus transformation related extracellular enzyme activity and its main controlling factors; on this basis, the typical Karst and adjacent Karst forest soil enzyme the activity to carry out a comparative study. The main conclusions are as follows: (1) in the process of vegetation restoration in Karst mountain area, soil hydrolase (involved in the decomposition of active carbon pool) and oxygen Enzyme activity (in inert carbon decomposition) the response results show that, with the vegetation restoration, soil hydrolase (i.e. beta glucosidase, alpha cellulose and beta xylosidase) activity increased (i.e., secondary forest, shrub grassland farmland) soil enzymes (peroxidase) activity had no obvious change in Karst area. After returning, along with vegetation restoration, the nitrogen cycle enzyme (i.e., leucine aminopeptidase, chitinase, urease, protease) activity increased. Correlation analysis showed that urease and protease and organic matter and total nitrogen were significantly correlated. The phosphatase activity and soil pH and exchangeable magnesium ions are related, but had no correlation with other physical and chemical nature, comprehensive analysis showed that: Karst area soil exchangeable magnesium ion has a positive effect on acid phosphatase, but no significant effect on alkaline phosphatase; analysis of the correlation between physicochemical indexes and soil phosphatase activity Found that the Karst area affected by soil phosphatase pH and exchangeable magnesium ions, there was no significant correlation with other measured physicochemical indexes. (2) Comparative Study on enzyme activity of Karst and non Karst area found that two regions belong to different soil types, the Karst area (alkaline calcareous soil) enzyme activity is generally higher than non Karst area (acid red soil), in addition to acid phosphatase and chitinase activity, measured by the other eight kinds of enzyme activity in the Karst area were significantly higher than non Karst area, two types of soil enzyme activity of the controlled factors are different, the Karst area controlled factor of non Karst area influence factor is more concentrated. (3) through the variance decomposition analysis of tree species, soil properties and soil type three sets of explanatory variables on soil enzyme activity results showed that the relative contribution of the three sets of explanatory variables in total solution The release of soil enzyme activity variation of 62.6%. among them, soil physical and chemical properties explained 58.2% of the variation of soil enzyme activity, soil type explained 38.7% of the variation of soil enzyme activity, species factors explain interaction between soil enzyme activity variation of 27.8%. three group variables, three common interpretation of the part is 17.8%. when excluding the 22 the common explanation part, the physical and chemical properties of soil net explained 23.4% of variation in soil enzyme activity, soil type net explain 3.9% of the variation of soil enzyme activity, net factor explains the species variation of soil enzyme activity 0.9%.

【学位授予单位】：广西师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S154.2

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