氮沉降对土壤微生物影响的研究进展

Effects of nitrogen deposition on soil microbes

土壤中氮沉降增加作为全球环境变化的重要现象之一,给人类带来了巨大挑战。笔者综述了近年来氮沉降对土壤微生物的影响研究,从土壤微生物生物量、群落结构和多样性、微生物活性、功能基因与底物利用等方面进行总结分析。综合来看,氮沉降对土壤微生物的影响主要表现为:1土壤微生物生物量、真菌生物量以及真菌与细菌生物量比值下降;2外生菌根真菌子实体生产力和外生菌根丰度下降,外生菌根真菌群落结构组成改变;3丛枝菌根真菌群落结构组成改变,但氮沉降对丛枝菌根真菌的多样性和对腐生真菌的影响结果存在较大争议;4细菌群落结构组成改变,贫营养细菌丰度下降,富营养细菌丰度上升;5土壤微生物活性下降,某些功能基因丰度下降,对复杂有机碳、氮的代谢能力下降。同时,相关研究报道表明:氮沉降可以直接或通过降低土壤p H,增加微生物的碳限制,改变底物的数量和质量等途径间接对微生物生物量和群落结构产生影响。

Increased nitrogen deposition may impact on soil microbes which play an important role in ecosystems. We re.viewed the effects of nitrogen deposition on soil microbes in respect of soil microbial biomass, microbial structure and di.versity, microbial activity, functional genes, and substrate utilization. In general, the potential effects of nitrogen deposi.tion included the following aspects：① Decreased soil microbial, fungal and the ratio of fungal to bacterial biomass;②Led to a reduction of the productivity of ectomycorrhizal fungal fruit body and the arbuscular mycorrhiza abundance;③Altered the structure of arbuscular mycorrhizal fungal community, but there were still some debates on the effects on ar.buscular mycorrhizal fungal diversity and saprophytic fungi;④The bacterial community structure changed. Oligotrophic bacterial abundance decreased, while copiotrophic bacterial abundance increased;⑤Soil microbial activity, some func.tional genes abundance and the catabolic capabilities of complex organic carbon and nitrogen decreased. Moreover, nitro.gen deposition have been shown to affect microbes direct or through decreasing soil pH, making microbes carbon.limited, changing the quantity and quality of litter indirectly.