增温对生物土壤结皮微生物群落组成及其呼吸作用的影响

Effects of warming on composition and respiration of microbial community in biological soil crusts

生物土壤结皮作为干旱区土壤表层主要的覆盖者,生存于其中的微生物在调节旱区碳循环的气候敏感性方面发挥着重要作用。目前气候变暖对生物结皮微生物群落及其呼吸作用的研究结论尚有分歧。为了更加准确预测未来干旱地区的碳收支,本文归纳了模拟气候变暖的增温试验中不同试验周期、不同季节和不同类型的生物结皮碳排放规律,并结合微生物丰度和有机碳的变化分析了引起碳排放差异的内在原因。短期增温(低于2 a)导致生物结皮中苔藓或地衣丰度显著性降低,从而增加土壤有机碳含量,碳排放量是否同步增加取决于土壤含水量。长期增温(大于5 a)降低了微生物对温度和湿度的敏感性,微生物丰度和组成趋于稳定,从而使有机碳含量和净碳排放量保持相对稳定。已有的研究结果揭示了生物结皮碳排放规律和原因,但微生物参与的内在调控机制仍不明确。因此,今后需重点探究结皮微生物碳代谢对增温的响应机制,为评估干旱区碳平衡提供重要理论依据。

Biological soil crusts are the main cover of the soil surface in arid areas,in which the microorganisms play an important role in regulating the climate sensitivity of carbon cycling in dry areas.At present,there are still disagreements in the studies on the effects of climate warming on the microbial communities and their respiration in biological soil crusts.This article summarized the emission patterns of carbon in biological soil crusts in different experimental cycles,seasons,and types of biological soil crusts through the warming experiments of simulating climate warming to more accurately predict the carbon balance in arid areas in the future.The intrinsic reasons for the differences in carbon emissions were analyzed by combining changes in microbial abundance and organic carbon.The results showed that short-term warming(below 2 year)led to a significant decrease in the abundance of moss or lichens in the biological soil crust,thereby increasing the content of organic carbon in soil,with a synchronous increase in the emissions of net carbon depending on the content of moisture in soil.Long-term warming(greater than 5 year)reduced the sensitivity of microorganisms to temperature and humidity,and the abundance and composition of microorganisms tended to stabilize,resulting in relatively stable content of organic carbon and the emissions of net carbon.The existing results reflect the patterns of and reasons for carbon emissions in biological soil crusts,but the underlying regulatory mechanisms involved by microorganisms are still unclear.Therefore,it is necessary to focus on studying the response mechanism of the carbon metabolism of microorganisms in biological soil crusts to warming in the future.It will provide important theoretical basis for evaluating carbon balance in arid areas.