發(fā)布時(shí)間：2018-05-31 06:03

  本文選題：土壤微生物呼吸 + 降水形式�。� 參考：《西北農(nóng)林科技大學(xué)》2017年碩士論文

【摘要】：陸地表面三分之一以上為干旱半干旱生態(tài)系統(tǒng),而降水是調(diào)節(jié)該區(qū)域水分和碳平衡的關(guān)鍵因素。土壤呼吸作為陸地生態(tài)系統(tǒng)碳循環(huán)的重要環(huán)節(jié),是陸地生態(tài)系統(tǒng)和大氣碳交換的最大組成部分。了解干旱半干旱地區(qū)土壤呼吸對(duì)極端降水的響應(yīng)特征及其影響因素,有助于深入了解氣候變化對(duì)此區(qū)域碳循環(huán)的影響。本研究依托中科院長(zhǎng)武生態(tài)試驗(yàn)站,依據(jù)該地區(qū)氣象數(shù)據(jù)資料,設(shè)置3種雨季總降水量(600 mm、300 mm、150 mm)和3種次降水量(10 mm、100 mm、150 mm,依次簡(jiǎn)稱“P10、P100、P150”)。選取農(nóng)田休閑季土壤,通過(guò)在短時(shí)間尺度上模擬雨季不同降水形式、不同底物和土壤氮素殘留量,在此條件下研究:1)土壤微生物呼吸對(duì)極端降水的響應(yīng);2)不同底物條件下土壤微生物呼吸對(duì)極端降水的響應(yīng);3)不同氮素條件下土壤微生物呼吸對(duì)極端降水的響應(yīng)。主要結(jié)果如下:(1)降水形式變化顯著影響土壤微生物呼吸速率動(dòng)態(tài)變化及土壤累積呼吸量。相同總降水量下,P150下土壤微生物呼吸速率波動(dòng)較P10劇烈;不同雨季降水量下,土壤累積呼吸量隨降水變化呈現(xiàn)600 mm300 mm150 mm的趨勢(shì);相同降水量下,600 mm總降水量下土壤累積呼吸量表現(xiàn)為P10P150的趨勢(shì);150 mm降水量下趨勢(shì)相反:P150P10;300 mm降水量下則無(wú)顯著差異。土壤微生物呼吸的水分脅迫時(shí)間是影響土壤微生物呼吸累積量的重要因素。(2)底物添加顯著影響土壤微生物呼吸對(duì)降水的動(dòng)態(tài)響應(yīng)及土壤累積呼吸量。添加秸稈后,土壤呼吸速率隨水分變化波動(dòng)更加劇烈,其中P100下更明顯;土壤累積呼吸量隨總降水量的增加而增大(P10:176 g·m-2 vs 299 g·m-2;P100:305 g·m-2 vs 368 g·m-2),而隨次降水量的增加,300 mm總降水量下土壤累積呼吸量增大了73%(176 g·m-2 vs 305g·m-2),顯著高于600 mm總降水量下土壤微生物呼吸的增大幅度23%(299 g·m-2 vs 368g·m-2)。(3)氮素在土壤微生物呼吸對(duì)降水的響應(yīng)過(guò)程中無(wú)顯著影響(P0.05)。在本研究中,氮素對(duì)土壤微生物呼吸表現(xiàn)出輕微抑制作用與降水對(duì)土壤微生物呼吸的激發(fā)效應(yīng)表現(xiàn)出相互抵消;而添加秸稈后,施氮對(duì)土壤呼吸的抑制效果有略微增強(qiáng)趨勢(shì)(P0.05),且次降水量相同條件下,添加氮素后300 mm總降水量下土壤累積呼吸量下降幅度略大于600 mm總降水量。極端降水事件顯著影響土壤CO_2通量變化,且土壤氮素和底物是影響該過(guò)程的重要因素。評(píng)估氣候變化條件下,干旱半干旱區(qū)土壤CO_2通量變化需考慮降水形式變化及土壤性質(zhì)的影響。
[Abstract]:The land surface above 1/3 is an arid and semi-arid ecosystem, and precipitation is the key factor to regulate the water and carbon balance in the region. Soil respiration, as an important part of terrestrial ecosystem carbon cycle, is the largest component of terrestrial ecosystem and atmospheric carbon exchange. Understanding the response of soil respiration to extreme precipitation and its influencing factors in arid and semi-arid areas is helpful to understand the effect of climate change on the carbon cycle in this region. Based on the meteorological data of Changwu Ecological Experimental Station of the Chinese Academy of Sciences, three kinds of rainy season total precipitation of 600 mm ~ 300 mm ~ 150 mm) and three kinds of secondary precipitation of 10 mm ~ 100 mm ~ 150 mm are set up, which are referred to as "P10 P100 + P150" in turn. In the short time scale, different rainfall forms, different substrates and soil nitrogen residues were simulated on a short scale by selecting farmland soil in leisure season. Under this condition, the response of soil microbial respiration to extreme precipitation was studied. (2) the response of soil microbial respiration to extreme precipitation under different substrate conditions. (3) the response of soil microbial respiration to extreme precipitation under different nitrogen conditions. The main results were as follows: (1) the change of precipitation form significantly affected the dynamic changes of soil microbial respiration rate and soil cumulative respiration. Under the same total precipitation, soil microbial respiration rate fluctuated more sharply than that of P10, and soil cumulative respiration showed a trend of 600 mm300 mm150 / mm with precipitation in different rainy seasons. Under the same precipitation, there was no significant difference in the trend of soil cumulative respiration with P10P150 under the same precipitation ( P150P1010 / 300mm). Water stress time of soil microbial respiration was an important factor affecting soil microbial respiration accumulation.) substrate addition significantly affected the dynamic response of soil microbial respiration to precipitation and soil cumulative respiration. After adding straw, the soil respiration rate fluctuated more sharply with the change of water content, especially under P100. Soil cumulative respiration increased with the increase of total precipitation (P 10: 176 g m -2 vs 299 g m -2 vs 299g m -2 P 100 305 g m -2 vs 368 g m -2), and the soil cumulative respiration increased by 73% 176 g m -2 vs 305 g m -2 under 300 mm total precipitation, which was significantly higher than that under 600 mm total precipitation. The increasing range of microbial respiration was 299g m ~ (-2) vs 368g m ~ (-2).) nitrogen had no significant effect on the response of soil microbial respiration to precipitation. In this study, the slight inhibition of nitrogen on soil microbial respiration and the stimulation effect of precipitation on soil microbial respiration were counteracted. The inhibition effect of nitrogen application on soil respiration showed a slight increasing trend (P0.05), and under the same condition of secondary precipitation, the soil cumulative respiration decreased slightly more than 600 mm under the condition of 300 mm total precipitation after nitrogen was added. Extreme precipitation events significantly affected the change of soil CO_2 flux, and soil nitrogen and substrate were important factors affecting the process. In order to evaluate the climate change, the change of soil CO_2 flux in arid and semi-arid region should be taken into account in the change of precipitation form and the influence of soil properties.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：S154.1

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