冰川消退带微生物群落演替及生物地球化学循环

冰川是生物圈重要组分之一。由于全球气候变化世界多地冰川加速消融,暴露原本被冰盖覆盖的区域,这些区域被称为冰川消退区域(glacier retreat area)或冰川前部区域(glacier foreland)。自暴露开始消退区随即发生初生演替,随着演替进行,物质循环逐步建立,生物量和土壤C、N总量逐步增加。生态系统C、N输入最初以矿化外来物为主,逐渐转变为以生物固C、固N为主。演替早期生态系统的发育主要受土壤C、N含量的限制,而演替后期的限制性营养物转变为P。演替区域土壤逐渐发育并促进生态位的分化,细菌、真菌、古菌,病毒及其他微生物群落的生物量和多样性不断增加直至达到该地区可承受的极值。随着生存条件的改善,不同生态策略物种的更替导致每个演替阶段微生物群落结构的差异。整体上,伴随演替进行微生物群落丰度、结构和活性呈现梯度性变化。气候变化对冰川消退带生态演替结果产生多方面的影响,而这些影响结果又综合反馈气候变化,因此目前难以准确估计气候变化对消退带生态演替的净效应。综述了近年冰川消退带微生物群落演替方面相关的研究结果,同时分别对该区域物质循环的建立、微生物群落演替和气候变化造成的影响这三个方面进行详细描述,并指出当前研究的不足。

Microbial community succession in glacier retreat area and the biogeochemical cycles

The glacier is one of the most important parts of the biome. Because of global climate change, the retreat of most glaciers worldwide has been accelerated and areas are exposed that the retreated ice cap had covered. These areas are called glacier retreat areas or glacier foreland, and primary succession begins there when the area is exposed. With succession moving forward, cycles of matters are built step by step, biomass and total amounts of soil C and N biological increase gradually. The C and N input into the ecosystem is originally primarily supported by mineralization of allochthonous matter and gradually shifts to primarily C and N fixation. The ecosystem development is mainly limited by soil C and N content the early stages of succession, whereas P turns into the primary limit factor at the last stage of succession. Soil develops gradually through the successional area and accelerates niche differentiation, microbial community biomass, and diversity of bacteria, archea, fungi, viruses and other types of microbes increase until the climax community that the area is capable of supporting. With the amelioration of habitats, the replacement of different microbes that possess different eco-strategies leads to variation in the microbial community in each successional stage. Over all, the abundance, structure, and activity of the microbial community presents a gradient of variation with the pace of succession. Global climate change exerts multiple effects on the successional results of glacier retreat areas and feedback synthetically to climate change, thus making it difficult to estimate the net effect that climate change exerts on ecosystem succession in glacier retreat areas. This paper reviews recent research results with regard to microbial community succession in glacier retreat areas and comprehensively describes three aspects of cycles of matters, microbial community succession, and effects from climate change, and points out the weakness and gaps in our present knowledge.