Soil samples were collected from an alpine coniferous forest. Soil cores with soil organic layer above and mineral soil layer below were incubated in plant growth chambers during 10 weeks. Taking the annual average soil temperature in the alpine forest as the control, and other two levels of temperature were increased 2 and 4 ℃, respectively, to investigate the responses of soil microbial community and soil enzyme activity to warming. The results showed that warming significantly reduced PLFAs content of bacteria in soil organic layer and PLFAs content of G- in the mineral soil layer, whereas soil fungi was slightly influenced by warming. Warming caused the G+/G- increasing and changed the microbial community structure, but had no significant effect on soil enzymes activity, i.e., laccase (Lac), β-1,4-glucoside (BG), acid phosphate (AP), β-1,4-N-acetylglucosaminidase (NAG). There were significantly positive correlations between fungi, bacteria, G+ and G-, showing the coordinated growth trend between soil microbial communities. There was significantly negative correlation between BG and bacteria, showing the BG competing for carbon source utilization with soil microbial community. In consequence, the soil microbe types responded differently to warming. Bacteria were more sensitive to temperature than fungi, and fungi had stronger ability to tolerate warming in the alpine forest.
将高山森林土壤装入PVC管中(土壤有机层在上、矿质土壤层在下)培养10周,以高山森林土壤年均温为对照,采用室内人工气候箱分别模拟增温2和4 ℃,研究土壤微生物群落和土壤酶活性对温度升高的响应.结果表明: 温度升高显著降低了土壤有机层中细菌、矿质土壤层中革兰氏阴性菌(G-)PLFAs含量,但对土壤真菌无显著影响.温度升高引起革兰氏阳性菌和阴性菌比值(G+/G-)升高,改变了微生物群落结构.增温对漆酶、β-葡萄糖酶、酸性磷酸酶和N-乙酰葡糖胺糖苷酶活性没有显著影响.土壤微生物群落之间呈现出协同增长的趋势,真菌、细菌、G+、G-等微生物群落之间均呈显著正相关.土壤有机层中β-葡萄糖苷酶与土壤微生物群落对碳源利用的竞争,导致β-葡萄糖苷酶活性与土壤有机层细菌、真菌、G+呈显著负相关.高山森林不同土壤微生物类群对增温的响应不同,细菌比真菌对温度的响应更敏感,真菌对增温有一定的耐受能力.
Keywords: alpine forest; phospholipid fatty acid (PLFA); simulated warming; soil enzyme activity; soil microbial community.