本文選題：貝加爾針茅草甸草原 + 凋落物分解　； 參考：《東北師范大學(xué)》2017年碩士論文

【摘要】：大氣氮沉降增加和降水格局改變影響草原生態(tài)系統(tǒng)的凋落物分解以及營養(yǎng)元素循環(huán)。但是,目前增氮、增雨及增氮與增雨交互處理對草原生態(tài)系統(tǒng)的土壤理化特征及凋落物分解的影響規(guī)律與機制還不十分清楚。本文以貝加爾針茅草甸草原土壤為研究對象,在野外原位條件下進行模擬增雨和增氮的控制實驗,增氮量為5 g N m-2 a-1、10 g N m-2 a-1、增雨量為自然降水的14%和28%,自然降水且不增氮為對照,增氮與增雨二因素交互設(shè)計,研究模擬增氮、增雨對土壤理化特性和凋落物分解速率的影響,探討凋落物分解季節(jié)動態(tài)變化規(guī)律,分析影響凋落物分解的主要土壤環(huán)境因子的作用。本研究對于深入理解草原生態(tài)系統(tǒng)凋落物分解對全球變化的響應(yīng)過程與機制具有重要意義。主要研究結(jié)果與結(jié)論如下:(1)貝加爾針茅草甸草原的土壤理化特性受增氮、增雨、季節(jié)及三者交互作用影響顯著(P0.05)。增氮、增雨以及二者互作均顯著(P0.05)或極顯著地(P0.01)增加了土壤速效N含量、土壤速效P含量,降低了土壤總有機碳含量(P0.05)。這說明,增氮和增雨對草地土壤N、P的利用和轉(zhuǎn)化有一定的促進作用,而對土壤總有機碳貯存有一定的抑制作用。(2)凋落物分解速率和凋落物質(zhì)量呈現(xiàn)明顯的季節(jié)變化特征�？傮w上,凋落物質(zhì)量隨季節(jié)推移而逐漸降低。凋落物經(jīng)過2015年的分解之后,2016年凋落物纖維素、半纖維素含量顯著(P0.01)降低,而木質(zhì)素含量顯著(P0.01)增加。增雨、增氮和二者互作處理顯著降低凋落物的纖維素含量,且增加了凋落物的N含量,降低了凋落物C含量和C/N值。總體上,增氮促進凋落物分解(P㩳0.05),而增雨對凋落物分解有阻礙作用,而氮、水耦合在一定程度上會促進貝加爾針茅草甸草原的凋落物分解。(3)相關(guān)性分析結(jié)果表明,土壤溫度、土壤含水量、土壤pH和土壤營養(yǎng)元素含量是影響貝加爾針茅草甸草原凋落物分解的重要生態(tài)因子。增氮使凋落物的分解速率與土壤溫度和含水量的相關(guān)性降低,增雨使凋落物的分解速率與土壤溫度的相關(guān)性提高,而增氮、增雨交互作用則促進了凋落物的分解。這說明,增氮和增雨對貝加爾針茅草甸草原凋落物分解的小環(huán)境有重要影響,兩者交互作用的影響更為突出。
[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.
【學(xué)位授予單位】：東北師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S812.2

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