氮沉降对北方森林土壤微生物的影响研究进展

Research Progress of Nitrogen Deposition Effect on Soil Microorganism in Boreal Forest

大气氮沉降导致土壤有效氮含量增加,将改变作为陆地生态系统重要组成部分的土壤微生物群落结构,尤其在高纬度氮限制地区,土壤微生物对这种变化更为敏感。北方森林地处高纬度地区,氮沉降将改变其土壤微生物的结构、功能和动态。为全面了解近年来氮沉降对北方森林土壤微生物的影响,笔者综述了氮沉降对北方森林土壤微生物量、群落结构和生物多样性、功能和酶活性等方面的影响。结果表明:(1)氮沉降减少了土壤微生物量;(2)氮沉降改变土壤中真菌与细菌,革兰氏阴性细菌(G-)与革兰氏阳性细菌(G+)之间的比值,而这种改变大多数是趋向于减小;(3)氮沉降加剧,将导致土壤微生物群落中贫营养微生物处于劣势地位,富营养微生物处于优势地位,间接地影响了微生物群落结构和生物多样性;(4)氮沉降抑制了微生物呼吸,但对于土壤酶的影响尚无统一规律;(5)氮沉降改变了微生物底物利用模式,导致土壤微生物对复杂有机物质的分解能力下降;(6)氮沉降导致固氮基因等功能基因相对丰度下降。

Atmospheric nitrogen deposition leads to an increase in available nitrogen（N） content in the soil,which will change the soil microbial community structure as an important part of terrestrial ecosystem,especially in the area of high latitude N limitation, soil microorganisms are more sensitive to this change. Theboreal forest is located in high latitude, and N deposition will change soil microbial community structure,function and dynamics. To fully understand the effect of N deposition on soil microbes in boreal forest, theauthors summarized the effect of N deposition on boreal forest soil microbial biomass, community structure andbiodiversity, function and enzyme activity and so on. The results showed that：（1） N deposition reduced soilmicrobial biomass;（2） nitrogen deposition altered the ratio between fungi and bacteria, Gram-negative bacteria（G-） and Gram-positive bacteria（G＋） in soil, most of the change tended to decrease;（3） the increase of Ndeposition might lead to nutrient poor microorganisms in disadvantaged status and nutrient richmicroorganisms in dominant position in soil microbial communities, which indirectly affected the microbialcommunity structure and biodiversity;（4） N deposition inhibited microbial respiration, but the influence on soil enzyme had no uniform law;（5） N deposition changed microbial substrate utilization patterns, which led to thedecline of soil microbial decomposition of complex organic matter;（6） N deposition resulted in a decrease inthe relative abundance of N fixing genes and other functional genes.