增氮增雨对贝加尔针茅草甸草原土壤理化特征及凋落物分解的影响

发布时间：2018-07-09 19:47

本文选题：贝加尔针茅草甸草原 + 凋落物分解　；参考：《东北师范大学》2017年硕士论文

【摘要】：大气氮沉降增加和降水格局改变影响草原生态系统的凋落物分解以及营养元素循环。但是,目前增氮、增雨及增氮与增雨交互处理对草原生态系统的土壤理化特征及凋落物分解的影响规律与机制还不十分清楚。本文以贝加尔针茅草甸草原土壤为研究对象,在野外原位条件下进行模拟增雨和增氮的控制实验,增氮量为5 g N m-2 a-1、10 g N m-2 a-1、增雨量为自然降水的14%和28%,自然降水且不增氮为对照,增氮与增雨二因素交互设计,研究模拟增氮、增雨对土壤理化特性和凋落物分解速率的影响,探讨凋落物分解季节动态变化规律,分析影响凋落物分解的主要土壤环境因子的作用。本研究对于深入理解草原生态系统凋落物分解对全球变化的响应过程与机制具有重要意义。主要研究结果与结论如下:(1)贝加尔针茅草甸草原的土壤理化特性受增氮、增雨、季节及三者交互作用影响显著(P0.05)。增氮、增雨以及二者互作均显著(P0.05)或极显著地(P0.01)增加了土壤速效N含量、土壤速效P含量,降低了土壤总有机碳含量(P0.05)。这说明,增氮和增雨对草地土壤N、P的利用和转化有一定的促进作用,而对土壤总有机碳贮存有一定的抑制作用。(2)凋落物分解速率和凋落物质量呈现明显的季节变化特征。总体上,凋落物质量随季节推移而逐渐降低。凋落物经过2015年的分解之后,2016年凋落物纤维素、半纤维素含量显著(P0.01)降低,而木质素含量显著(P0.01)增加。增雨、增氮和二者互作处理显著降低凋落物的纤维素含量,且增加了凋落物的N含量,降低了凋落物C含量和C/N值。总体上,增氮促进凋落物分解(P㩳0.05),而增雨对凋落物分解有阻碍作用,而氮、水耦合在一定程度上会促进贝加尔针茅草甸草原的凋落物分解。(3)相关性分析结果表明,土壤温度、土壤含水量、土壤pH和土壤营养元素含量是影响贝加尔针茅草甸草原凋落物分解的重要生态因子。增氮使凋落物的分解速率与土壤温度和含水量的相关性降低,增雨使凋落物的分解速率与土壤温度的相关性提高,而增氮、增雨交互作用则促进了凋落物的分解。这说明,增氮和增雨对贝加尔针茅草甸草原凋落物分解的小环境有重要影响,两者交互作用的影响更为突出。
[Abstract]:The increase of atmospheric nitrogen deposition and the change of precipitation pattern affect litter decomposition and nutrient cycling in grassland ecosystem. However, the effects of nitrogen, rain and interaction treatments on soil physical and chemical characteristics and litter decomposition of grassland ecosystem are still unclear. In this paper, the soil of Stipa baicalensis meadow was used as the research object, and the control experiment of simulated rain and nitrogen increase was carried out in the field in situ. The nitrogen increment was 5 g N m-2 a-1 + 10 g N m-2 a-1, and the precipitation rate was 14% and 28% of that of the natural precipitation. The effects of precipitation on soil physicochemical properties and litter decomposition rate were studied. The seasonal dynamic change of litter decomposition was discussed and the effects of main soil environmental factors on litter decomposition were analyzed. This study is of great significance in understanding the response process and mechanism of litter decomposition to global change in grassland ecosystem. The main results and conclusions are as follows: (1) the soil physical and chemical characteristics of Stipa baicalensis meadow were significantly affected by nitrogen, rain, season and interaction among them (P0.05). Nitrogen, rain and interaction were significant (P0.05) or extremely significant (P0.01) increased soil available N content, soil available P content, decreased soil total organic carbon content (P0.05). The results indicated that nitrogen and rain could promote the utilization and transformation of N ~ + P in grassland soil, but inhibit the storage of soil total organic carbon. (2) the decomposition rate of litter and the quality of litter had obvious seasonal variation characteristics. On the whole, the quality of litter decreased with the season. After litter decomposition in 2015, cellulose content and hemicellulose content in litter decreased significantly (P0.01) and lignin content increased significantly (P0.01) in 2016. The treatments of increasing rain, increasing nitrogen and the interaction of both decreased the cellulose content, increased N content, decreased C content and C / N value of litter. On the whole, nitrogen increase can promote litter decomposition (P0. 05), but increasing rain can hinder litter decomposition, and nitrogen and water coupling can promote litter decomposition in Stipa baicalensis meadow to some extent. (3) correlation analysis results show that soil temperature, soil temperature and soil temperature. Soil water content, soil pH and soil nutrient content were important ecological factors affecting litter decomposition in Stipa baicalensis meadow. Increasing nitrogen reduced the correlation between decomposition rate of litter and soil temperature and water content, increasing rainfall increased the correlation between decomposition rate of litter and soil temperature, while the interaction of nitrogen and rain increased the decomposition of litter. The results showed that nitrogen and rain had an important effect on the litter decomposition environment of Stipa baicalensis meadow, and the interaction between them was more prominent.
【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S812.2

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