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开展亚高山针叶林典型林地土壤有效氮和微生物特性对气候变化的响应研究,对预测未来气候变化背景下亚高山针叶林生态系统C、N的源/汇功能具有重要意义。该文采用红外辐射加热器模拟增温结合外施氮肥的方法,研究了川西亚高山针叶林下土壤化学特性、有效氮含量以及微生物生物量对夜间增温和施氮的短期响应。结果表明:在模拟增温试验期间(2009年4月–2010年4月),空气平均温度和5cm土壤平均温度分别比对照提高了1.93和4.19℃,增温幅度分别以夏季和冬季最为显著。增温对土壤pH值、有机碳、全氮和微生物生物量无显著影响。增温在试验前期降低了土壤NH4+-N含量,增加了NO3–-N含量,其影响程度随着增温时间的延长而下降。施氮显著增加了有效氮和微生物生物量氮,降低了土壤pH值,使土壤表现出明显的酸化现象。与单独的增温和施氮处理相比,增温和施氮联合处理对林下土壤的有效氮和微生物特性有显著的交互作用,显著增加了土壤的有机碳、有效氮及土壤微生物生物量氮含量,并导致土壤进一步酸化。结果说明,川西亚高山针叶林的土壤有效氮和微生物特性对土壤氮素状况的变化反应敏感,而林下土壤有效氮和微生物特性对单独的温度升高表现出一定的适应性,但更对增温和施氮双因素结合处理反应敏感且表现出不同的响应方式。因此,该区域在未来全球变化下的氮沉降状况及气候变化的多因素协同效应值得长期深入的探讨。
To study the response of soil available nitrogen and microbial characteristics to climate change in typical subalpine coniferous forest land is of great significance in predicting the source / sink function of C and N in the subalpine coniferous forest ecosystem in the future climate change. In this paper, the infrared radiation heater was used to simulate the warming and nitrogen fertilizer application. The short-term response of soil chemical properties, available nitrogen and microbial biomass to nighttime warming and nitrogen application in the subalpine coniferous forest of western Sichuan was studied. The results showed that air temperature and average soil temperature increased by 1.93 and 4.19 ℃ respectively during the simulated temperature increase experiment (Apr. 2009-Apr. 2010), the most significant increase was in summer and winter respectively. Temperature warming had no significant effect on soil pH, organic carbon, total nitrogen and microbial biomass. The warming reduced the content of NH4 + -N in the soil and increased the content of NO3 - N in the early stage of the experiment, and the influence degree decreased as the warming time prolonged. Nitrogen addition significantly increased nitrogen and microbial biomass nitrogen, decreased soil pH and resulted in significant soil acidification. Compared with the independent warming and nitrogen treatments, the combination of warming and nitrogen application had significant interaction on available nitrogen and microbial characteristics of undergrowth soil, and significantly increased soil organic carbon, available nitrogen and soil microbial biomass Nitrogen content and lead to further soil acidification. The results showed that soil available nitrogen and microbial characteristics of subalpine coniferous forest in western Sichuan were sensitive to changes of soil nitrogen status, while available N and microbial characteristics of subsoil showed some adaptability to individual temperature increase, but more It is sensitive to the combination of warming and nitrogen application and shows different response modes. Therefore, the nitrogen deposition in the region in the future global changes and the multi-factor synergy of climate change deserve long-term and in-depth discussion.