滨海芦苇湿地土壤微生物数量对长期模拟增温的响应

采用开顶式生长室(Open-top chamber,OTC)连续8 a(2008~2015年)长期模拟温度升高,研究滨海芦苇湿地不同土壤深度,及两种代表植物芦苇(Phragmites australis)和白茅(Imperata cylindrical)根际、非根际土壤可培养微生物数量变化对长期增温的响应。结果表明:(1)相对于对照,长期增温导致土壤可培养微生物的数量显著增加。其中,增温对土壤表层细菌、真菌的数量影响显著,细菌在第一层的增幅最大,增加率为34.16%,真菌在第三层的增幅最大,增加了64.42%。增温对20~40 cm土层放线菌影响显著,其中在第二层达到最大增加率59.47%;(2)长期增温对芦苇根际土壤微生物的根际效应变化的影响不大,表现为各土层芦苇根际效应增温对照,而白茅根际真菌和放线菌分别在第二层和第三层有显著差异;(3)不同的植物类型,其根际可培养微生物数量及根际效应对长期增温的响应不一致,表现为芦苇和白茅根际土壤可培养微生物数量及根际效应的增加幅度不同,这可能与植物不同类型,根际分泌物种类、数量的差异有关。

RESPONSES OF SOIL MICROORGANISM QUANTITY TO SIMULATED TEMPERATURE ENHANCEMENT IN THE COASTAL PHRAGMITES AUSTRALIS WETLAND

By using the method of open-top growth chambers (OTC) to simulate temperature enhancement for 8 consecutive years(2008-2015), the study studied the response of different soil layers and rhizosphere and non-rhizosphere of Phragmites australis and Imperata cylindrica culturable soil microbial quantity change to long-term simulated temperature enhancement in coastal wetland in Estern Chongming Island. The results showed that:(1) long-term warming resulted in the quantity of culturable soil microbial increased greatly in warming group than in control group. Warming had a significant effect on the quantity of bacteria, fungi in surface layer. Bacteria number reached the largest increasing rate of 34.16% in the first layer, while fungi number reached the largest increasing rate of 64.42% in the third layer. The effect of warming on actinomycetes was significant in 20-40cm layer, with the largest increasing rate of 59.47%.(2) Long-term warming had little impact on the rhizosphere effect change of reed, with a smaller effect in different layer in warming group. Rhizosphere fungi and actinomycetes of Imperata cylindrical differed obviously in second and third layer, respectively. (3) The study showed different responses of soil culturable microorganism quantity and rhizosphere effect of different plants to long-term warming. There were different increasing percentage of soil culturable microorganism quantity and rhizosphere effect between Phragmites australis and Imperata cylindrical. It might be related to the plant type, the kind and quantity of rhizosphere secretion.