杉木人工林土壤呼吸对干旱及氮沉降的响应研究

发布时间：2018-03-21 11:20

  本文选题：土壤呼吸　切入点：微生物呼吸　出处：《中南林业科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：土壤呼吸是陆地生态系统碳循环的最重要的环节之一,是土壤碳库的主要输出途径和大气cO2的重要来源,其微小的变化就会显著地减缓或加剧大气中CO2的增加,进而影响气候变化,森林土壤碳库是全球土壤碳库的重要组成部分,其比例约为73%。因此对森林土壤呼吸的研究是研究碳失汇现象以及包括全球变化在内等一系列重大环境问题的重要组成部分。本研究以湖南会同杉木林生态系统国家野外科学观测研究站试验基地的杉木人工林为对象,分别设立对照组、干旱组、低氮组和高氮组,共12块实验样地。每个样地内设去凋落物观测点、去根观测点、无处理观测点各3个,定期监测各观测点土壤总呼吸速率以及土壤呼吸组分(根呼吸和微生物呼吸速率),以探究杉木人工林土壤呼吸及各组分对干旱及氮沉降的响应机理,并对未来森林土壤呼吸情况,全球碳循环预测等其他相关研究提供科学研究数据,主要研究结果为:1.模拟氮沉降时,土壤总呼吸年平均速率为对照组1.53μmol/(m2·s)高氮组1.46μmol/(m2·s)低氮组1.24μmol/(m2·s)。从趋势来看模拟不同水平的氮沉降处理均会对杉木人工林土壤总呼吸产生抑制效果,在模拟低水平氮沉降时效果更明显,模拟不同水平的氮沉降处理均会对土壤呼吸组分的比例发生变化,使得微生物呼吸上升,植物根系呼吸下降,在低氮水平下,这种提升达到了 30.1%。2.隔离降雨总体上使得土壤总呼吸速率1.43μmol/(m2·s)比对照组l.53μmol/(m2·s)低,但差异不显著,但在隔离降雨10个月后,土壤总呼吸及各组分呼吸均表现出上升趋势。而去除凋落物对杉木人工林土壤呼吸的影响极为微小。3.土壤温度是影响实验地杉木人工林土壤呼吸的主要因素,温度可以解释实验地土壤总呼吸62.4-73.9%的变异,土壤微生物呼吸55.1-69.5%的变异,在模拟高水平氮沉降的条件下,土壤总呼吸的Q10值有所上升,而模拟低水平氮沉降和模拟干旱条件下,土壤总呼吸的Q10值有所下降。模拟氮沉降和干旱均使得土壤微生物呼吸的Q10值上升。土壤湿度对实验地杉木人工林土壤呼吸的影响较小,仅能解释土壤总呼吸的6.2%到22.9%的变异,土壤微生物呼吸11.1-24.7%的变异,模拟氮沉降和干旱处理后,土壤湿度与土壤微生物呼吸的关系进一步削弱。而低氮水平下土壤湿度与土壤总呼吸的关系有所加强。
[Abstract]:Soil respiration is one of the most important processes of terrestrial ecosystem carbon cycle, and it is the main output pathway of soil carbon pool and the important source of atmospheric cO2. The small change of soil respiration will significantly slow or aggravate the increase of CO2 in the atmosphere. Thus affecting climate change, forest soil carbon pool is an important component of global soil carbon pool, Therefore, the study of forest soil respiration is an important part of the study of carbon sequestration and a series of major environmental problems, including global change. The Cunninghamia lanceolata plantation in the experimental base of the field scientific observation and research station, Control group, drought group, low nitrogen group and high nitrogen group were set up with 12 experimental plots. Soil total respiration rate and soil respiration components (root respiration and microbial respiration rate) were monitored regularly in order to explore the mechanism of soil respiration and its response to drought and nitrogen deposition in Chinese fir plantation. And provide scientific data for future forest soil respiration, global carbon cycle prediction and other related studies. The main results are: 1. When simulating nitrogen deposition, The annual average rate of soil total respiration was 1.53 渭 mol/(m2 路s in control group (1.46 渭 mol/(m2 路s) in high nitrogen group (1.46 渭 mol/(m2 路s)) in low nitrogen group (1.24 渭 mol/(m2 路s). According to the trend, nitrogen deposition at different levels could inhibit soil total respiration in Chinese fir plantation, especially when simulating low nitrogen deposition. Simulation of nitrogen deposition at different levels will change the proportion of soil respiration components, resulting in the increase of microbial respiration, the decline of plant root respiration, and the decrease of plant root respiration at low nitrogen level. The total respiration rate of the soil was lower than that of the control group (1.43 渭 mol/(m2 路s), but the difference was not significant, but after 10 months of isolated rainfall, the total respiration rate of the soil was lower than that of the control group (1.43 渭 mol/(m2 路s). Soil total respiration and components respiration showed an upward trend, while the effect of litter removal on soil respiration of Chinese fir plantation was very small. 3. Soil temperature was the main factor affecting soil respiration in Chinese fir plantation. The temperature can explain 62.4-73.9% variation of soil total respiration and 55.1-69.5% variation of soil microbial respiration. Under the condition of simulating high nitrogen deposition, the Q10 value of soil total respiration increased, but under simulated low level nitrogen deposition and simulated drought condition, Q10 value of soil total respiration increased. The Q10 value of soil total respiration decreased. Simulated nitrogen deposition and drought increased the soil microbial respiration Q10 value. Soil moisture had little effect on soil respiration of Chinese fir plantation, which could only explain the variation of soil total respiration between 6.2% and 22.9%. The variation of soil microbial respiration was 11.1-24.7%. After simulated nitrogen deposition and drought treatment, the relationship between soil moisture and soil microbial respiration was further weakened, but the relationship between soil moisture and soil total respiration was strengthened at low nitrogen level.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714
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本文编号：1643623