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土壤微生物作为生态系统分解者,在物质循环和能量流动中起着重要作用。人类活动引起的氮沉降增加会直接或间接改变土壤微生物结构和功能,最终影响生态系统物质循环和能量流动。于2012年5月起每月月初添加硝酸铵模拟不同梯度氮沉降(5.6、15.6、20.6 g N·m~(-2)·a-1),2013年4月中旬(雨季)和10月中旬(旱季)运用磷脂脂肪酸(PLFAs)法研究氮沉降对马尾松(Pinus massoniana)、海南红豆(Ormosia pinnata)、荷木(Schima superba)和马占相思(Acacia mangium)4个树种土壤微生物群落结构的影响。结果表明:随氮沉降水平的增加,土壤微生物总PLFAs降低,但细菌仍然是土壤微生物的优势类群。旱季土壤微生物PLFAs高于雨季。土壤微生物与土壤含水率、p H和总氮具有显著相关性。雨季土壤微生物主要受p H和含水率影响,而旱季土壤微生物主要受养分的影响。氮沉降胁迫下,固氮树种海南红豆和马占相思土壤微生物PLFAs高于其他树种。采样时间、氮水平和树种对土壤微生物(总土壤微生物、细菌、真菌和放线菌)PLFAs有显著影响,但没有显著改变土壤F/B值。因此,在研究氮沉降对土壤微生物的影响时,需综合考虑氮沉降时间效应、氮沉降水平和不同树种的影响,以便更好地为环境保护以及生态系统可持续发展等提供科学依据。
Soil microorganisms, as ecosystem decomposers, play an important role in material circulation and energy flow. The increase of nitrogen deposition caused by human activities will directly or indirectly change the structure and function of soil microorganisms and ultimately affect the ecosystem material circulation and energy flow. At the beginning of each month from May 2012, ammonium nitrate was added to simulate different gradient nitrogen depositions (5.6,15.6,20.6 g N · m -2 · a -1), mid-April 2013 (rainy season) and mid-October (Dry Season) Phospholipid fatty acids (PLFAs) were used to study the effects of nitrogen deposition on soil microbial community structure in four species of Pinus massoniana, Ormosia pinnata, Schima superba and Acacia mangium influences. The results showed that with the increase of nitrogen deposition, the total PLFAs of soil microorganisms decreased, but the bacteria were still the dominant groups of soil microorganisms. The dry season soil microbial PLFAs higher than the rainy season. Soil microorganisms had significant correlation with soil water content, p H and total nitrogen. Soil microbes in rainy season are mainly affected by p H and water cut, while dry soil microbes are mainly affected by nutrients. Under nitrogen deposition stress, the PLFAs of soil microorganisms of Hainan red beans and Acacia mangium plants were higher than those of other species. Sampling time, nitrogen level and tree species had a significant effect on PLFAs of soil microorganisms (total soil microorganisms, bacteria, fungi and actinomycetes), but did not significantly change soil F / B values. Therefore, when studying the effect of nitrogen deposition on soil microorganisms, the effects of nitrogen deposition time, nitrogen deposition and different species should be considered in order to provide a scientific basis for environmental protection and ecosystem sustainable development.