Warming and drying suppress microbial activity and carbon cycling in boreal forest soils
Warming and drying suppress microbial activity and carbon cycling in boreal forest soils
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DOI：
10.1111/j.1365-2486.2008.01716.x
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发表时间：
2008-12-01
影响因子：
11.6
通讯作者：
Treseder, Kathleen K.
中科院分区：
文献类型：
--
作者：
Allison, Steven D.;Treseder, Kathleen K.
预计气候变暖将对苔原和北方生态系统产生特别强烈的影响，但相对较少的研究探讨了这些系统中土壤对温度变化的反应。我们使用封闭式温室，以研究土壤呼吸，养分供应，微生物丰度，和活跃的真菌群落土壤变暖的反应在阿拉斯加北部森林为主的成熟的黑云杉。这种处理使土壤温度提高了0.5摄氏度，也导致土壤含水量下降了22%。我们假设，微生物的丰度和活性将增加与温室处理。相反，我们发现细菌和真菌的丰度下降了50%以上，并且几丁质降解酶N-乙酰氨基葡萄糖苷酶的活性有降低的趋势。土壤呼吸也下降了50%，但只是在生长季节后期。这些变化是伴随着显着的变化，在活跃的真菌群落结构，减少相对丰度的优势Thelephoroid真菌和增加相对丰度的子囊菌和接合菌在变暖。与我们的假设一致，我们发现变暖略微增加了土壤铵和硝酸盐的可用性以及活性真菌的整体多样性。我们的研究结果表明，在北纬度生态系统的温度上升可能并不总是导致土壤碳循环的正反馈，特别是在北方森林与干燥的土壤。碳循环-气候反馈模型可以通过将土壤特性和整个寒带微生物群落的异质性纳入其中来提高其预测能力。
Climate warming is expected to have particularly strong effects on tundra and boreal ecosystems, yet relatively few studies have examined soil responses to temperature change in these systems. We used closed-top greenhouses to examine the response of soil respiration, nutrient availability, microbial abundance, and active fungal communities to soil warming in an Alaskan boreal forest dominated by mature black spruce. This treatment raised soil temperature by 0.5 degrees C and also resulted in a 22% decline in soil water content. We hypothesized that microbial abundance and activity would increase with the greenhouse treatment. Instead, we found that bacterial and fungal abundance declined by over 50%, and there was a trend toward lower activity of the chitin-degrading enzyme N-acetyl-glucosaminidase. Soil respiration also declined by up to 50%, but only late in the growing season. These changes were accompanied by significant shifts in the community structure of active fungi, with decreased relative abundance of a dominant Thelephoroid fungus and increased relative abundance of Ascomycetes and Zygomycetes in response to warming. In line with our hypothesis, we found that warming marginally increased soil ammonium and nitrate availability as well as the overall diversity of active fungi. Our results indicate that rising temperatures in northern-latitude ecosystems may not always cause a positive feedback to the soil carbon cycle, particularly in boreal forests with drier soils. Models of carbon cycle-climate feedbacks could increase their predictive power by incorporating heterogeneity in soil properties and microbial communities across the boreal zone.