模拟氮沉降对樟树林和湿地松林土壤呼吸的影响

发布时间：2018-03-27 13:34

本文选题：樟树　切入点：湿地松　出处：《中南林业科技大学》2015年硕士论文

【摘要】：上个世纪以来,全球范围内人类活动引发的陆地生态系统的氮输入增加了3-5倍,这一趋势仍在继续。中国亚热带地区已成为全球高氮沉降区之一,高氮输入对森林生态系统土壤呼吸等碳循环过程和生物生产力变化机制影响巨大。本研究以湖南省植物园的樟树林、湿地松林为研究对象,通过人工模拟氮沉降试验,设置对照(CK,0 kgN·hm-1·a-1)、低氮(LN,50 kgN·hm-2·a-1)、中氮(MN,150kgN·hn-1·a-1)、高氮(HN,300kgN·hm-1·a-1)4种模拟氮沉降水平,分析了樟树林、湿地松林土壤呼吸及其控制因素对模拟氮沉降处理的响应。主要结果如下：(1)4种模拟氮沉降浓度处理方式对樟树林、湿地松林土壤呼吸值日变化产生影响。樟树林样地在CK.LN.MN水平土壤呼吸最高值出现在晚上(22：00-4：00),最低值出现在中午12：00左右,HN水平最高值出现在中午12：00,且全天变化区间并不大；湿地松林样地4种模拟氮沉降浓度处理方式土壤呼吸值日变化不明显,最高值均出现上午9：00左右；樟树林、湿地松林在4种不同模拟氮沉降浓度处理下土壤呼吸速率均有相似的季节动态变化,与温度变化走势相近,峰值均出现在试验地温度最高的夏季(6-8月份),最低值均出现在试验地气温度最低的冬季(1-2月份)。(2)模拟氮沉降显著抑制樟树林、湿地松林土壤呼吸速率和年累积量,对照样地CK与LN.MN.HN样地的差异性显著(p0.05,n=9),3种模拟氮沉降处理均降低年累积量,但随时间的推移,模拟氮沉降对土壤呼吸的抑制效果随之减弱。2种林分之间年均土壤呼吸速率和土壤呼吸年累积量在3种模拟氮沉降浓度处理下差异性显著(p0.01),均表现为：樟树林湿地松林。(3)模拟氮沉降处理对2种森林类型的土壤呼吸速率的敏感系数Qlo的影响并不明显(p0.05)。樟树林在4种模拟氮沉降浓度处理下土壤呼吸的温度敏感系W10值表现出：LNCK)HN)MN;湿地松林土壤呼吸的温度敏感系数Q10表现出：CK)MNHN)LN;樟树林中的Q10值总体高于湿地松林。(4)土壤温度是影响土壤呼吸的主要因子之一,土壤温度控制土壤呼吸速率变异表现为：湿地松林樟树林。土壤湿度与土壤呼吸的关系不明显,土壤湿度对土壤呼吸影响表现为：樟树林湿地松林。(5)模拟氮沉降明显减少樟树林、湿地松林的有效氮,表现为：湿地松林樟树林,模拟氮沉降处理间无显著差异。模拟氮沉降增加了土壤中硝态氮的含量,且土壤硝态氮含量随模拟氮沉降水平升高而增大。在樟树林和湿地松林中,通过对土壤呼吸速率的日动态、季节动态、年均呼吸速率及年呼吸累积量的对比,不同模拟氮沉降浓度处理间均表现为：樟树林湿地松林。
[Abstract]:Since the last century, nitrogen input from terrestrial ecosystems caused by human activities worldwide has increased 3-5 times, a trend that continues. China's subtropical region has become one of the high nitrogen deposition areas in the world. High nitrogen input has a great influence on soil respiration and the mechanism of biological productivity change in forest ecosystem. This study took camphor forest and Pinus elliottii forest in Hunan Botanical Garden as the research object and simulated nitrogen deposition experiment. Four simulated nitrogen deposition levels, including CK 0 kgN hm-1 a-1, low N LNN 50 kgN hm-2 a-1, medium N MNN 150 kg N hn-1 a-1 and high N HN 300 kg N hm-1 a-1C, were set up, and the camphor forest was analyzed. Responses of soil respiration and its controlling factors to simulated nitrogen deposition in Pinus elliottii forest. The diurnal variation of soil respiration in Pinus elliottii forest was affected. The highest value of soil respiration at CK.LN.MN level appeared at 22: 00-4: 00 in the evening, and the lowest value appeared at around 12:00 at 12: 00 noon, and the whole day variation range was not large. The diurnal variation of soil respiration was not obvious in four simulated nitrogen concentration treatments of Pinus elliottii forest, and the highest value was about 9:00 in the morning. The soil respiration rate of Pinus elliottii forest was similar to that of temperature under four simulated nitrogen concentration treatments. The peak value appeared in June to August in summer when the temperature was the highest, and the lowest value was in the winter with the lowest air temperature. The simulated nitrogen deposition significantly inhibited the soil respiration rate and annual accumulated amount of camphor trees, Pinus elliottii forest, and Pinus elliottii forest. The difference between CK and LN.MN.HN plots was significant (p 0.05). All three simulated nitrogen deposition treatments decreased the annual accumulation, but with the time passing, the three simulated nitrogen deposition treatments decreased the annual accumulative capacity of CK and LN.MN.HN plots, but with the passage of time, there were significant differences between CK and LN.MN.HN plots. The inhibitory effect of simulated nitrogen deposition on soil respiration was decreased. 2. The average annual soil respiration rate and the annual accumulation of soil respiration were significantly different under the three simulated nitrogen deposition concentrations, all of which were: camphor forest wet. The effect of simulated nitrogen deposition on the sensitivity coefficient of soil respiration rate (Qlo) of two forest types was not obvious. The temperature sensitive line W10 of camphor forest under four simulated nitrogen deposition concentrations showed. The temperature sensitive coefficient Q10 of soil respiration in Pinus elliottii forest showed that the soil temperature was higher than that in Pinus elliottii forest, and the soil temperature was one of the main factors affecting soil respiration, and the Q10 value of camphor forest was higher than that of Pinus elliottii forest. The variation of soil respiration rate controlled by soil temperature was shown as follows: Pinus elliottii forest camphor forest, and the relationship between soil moisture and soil respiration was not obvious. The effect of soil moisture on soil respiration was as follows: Pinus elliottii forest. 5) simulated nitrogen deposition significantly reduced the available nitrogen of Pinus sylvestris forest, and the available nitrogen of Pinus elliottii forest was shown as follows: Pinus elliottii forest camphor forest. There was no significant difference between simulated nitrogen deposition treatments. Simulated nitrogen deposition increased the nitrate content in soil, and the nitrate nitrogen content in soil increased with the increase of simulated nitrogen deposition level. Through the comparison of daily, seasonal, annual and annual respiration rate and annual respiration accumulation of soil respiration rate, the different simulated nitrogen deposition concentration treatments were as follows: Pinus elliottii Pinus elliottii forest in camphor tree forest.
【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】：2015
【分类号】：S714

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