土壤呼吸对极端降水响应的模拟研究

发布时间：2018-05-31 06:03

本文选题：土壤微生物呼吸 + 降水形式　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：陆地表面三分之一以上为干旱半干旱生态系统,而降水是调节该区域水分和碳平衡的关键因素。土壤呼吸作为陆地生态系统碳循环的重要环节,是陆地生态系统和大气碳交换的最大组成部分。了解干旱半干旱地区土壤呼吸对极端降水的响应特征及其影响因素,有助于深入了解气候变化对此区域碳循环的影响。本研究依托中科院长武生态试验站,依据该地区气象数据资料,设置3种雨季总降水量(600 mm、300 mm、150 mm)和3种次降水量(10 mm、100 mm、150 mm,依次简称“P10、P100、P150”)。选取农田休闲季土壤,通过在短时间尺度上模拟雨季不同降水形式、不同底物和土壤氮素残留量,在此条件下研究:1)土壤微生物呼吸对极端降水的响应;2)不同底物条件下土壤微生物呼吸对极端降水的响应;3)不同氮素条件下土壤微生物呼吸对极端降水的响应。主要结果如下:(1)降水形式变化显著影响土壤微生物呼吸速率动态变化及土壤累积呼吸量。相同总降水量下,P150下土壤微生物呼吸速率波动较P10剧烈;不同雨季降水量下,土壤累积呼吸量随降水变化呈现600 mm300 mm150 mm的趋势;相同降水量下,600 mm总降水量下土壤累积呼吸量表现为P10P150的趋势;150 mm降水量下趋势相反:P150P10;300 mm降水量下则无显著差异。土壤微生物呼吸的水分胁迫时间是影响土壤微生物呼吸累积量的重要因素。(2)底物添加显著影响土壤微生物呼吸对降水的动态响应及土壤累积呼吸量。添加秸秆后,土壤呼吸速率随水分变化波动更加剧烈,其中P100下更明显;土壤累积呼吸量随总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),而随次降水量的增加,300 mm总降水量下土壤累积呼吸量增大了73%(176 g·m-2 vs 305g·m-2),显著高于600 mm总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对降水的响应过程中无显著影响(P0.05)。在本研究中,氮素对土壤微生物呼吸表现出轻微抑制作用与降水对土壤微生物呼吸的激发效应表现出相互抵消;而添加秸秆后,施氮对土壤呼吸的抑制效果有略微增强趋势(P0.05),且次降水量相同条件下,添加氮素后300 mm总降水量下土壤累积呼吸量下降幅度略大于600 mm总降水量。极端降水事件显著影响土壤CO_2通量变化,且土壤氮素和底物是影响该过程的重要因素。评估气候变化条件下,干旱半干旱区土壤CO_2通量变化需考虑降水形式变化及土壤性质的影响。
[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.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S154.1

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