近日，中科院华南植物园博士方熊在研究员周国逸和刘菊秀的指导下，发现气温上升对土壤团聚体微生物群落功能的影响。相关研究成果发表在《土壤微生物与土壤施肥》上。

研究气候变暖对土壤微生物过程的影响，对于预测土壤有机碳贮量对气候变暖的响应具有重要意义。目前，大量的模拟土壤增温对土壤微生物量、群落组成以及功能影响的研究结果尚存在较大争议。这其中一个重要原因可能是忽略了土壤不同团聚体中微生物具有不同的温度敏感性这一因素。

研究人员在鼎湖山森林生态系统定位研究站野外自然增温试验平台，开展了模拟增温对针阔叶混交林土壤不同团聚体的微生物量、群落组成及酶活性影响的研究。研究发现：土壤增温（~1℃）对不同团聚体的微生物总量没有显著影响，但显著改变了大团聚体（250~2000 微米）的微生物群落组成。同时，土壤增温显著增加了土壤三个粒径团聚体的多酚氧化酶和过氧化物酶活性。

据介绍，由外界因素引起的土壤有机碳分解的微小变化，都可能导致土壤有机碳库绝对量的变化，从而引起与大气碳库之间交换量的巨大变化，并对全球碳平衡和全球气候变暖产生重大影响。（来源：中国科学报 朱汉斌 周飞）

Warming effects on biomass and composition of microbial communities and enzyme activities within soil aggregates in subtropical forest

Abstract  This study investigated the effects of warming (about 1 °C) on the biomass and composition of microbial communities and enzyme activities in soil macroaggregates and microaggregates. We fractionated the bulk soils from the control and warming treatments into large macroaggregates (>2000 μm), small macroaggregates (250–2000 μm) and microaggregates (<250 μm) using the optimal moist sieving approach. Warming did not significantly affect soil microbial biomass in all aggregate fractions, but significantly altered the soil microbial community composition in the large macroaggregates. The G+:G− ratio was significantly higher in the small macroaggregates and microaggregates than that in the large macroaggregates in warmed soils, while the stress ratio was significantly higher in the large and small macroaggregates than that in the microaggregates. Soil warming did not significantly affect β-glucosidase, cellobiohydrolase and N-acetylglucosaminidase activities, but significantly decreased acid phosphomonoesterase activity and increased oxidase activities. Our results suggest that soil microbial community composition in the large macroaggregates might be more sensitive to warming. The differential responses of soil microbial communities and enzyme activities in different aggregate fractions in the warmed soils may have important implications for C cycling in subtropical forest ecosystems.

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