College of Grassland Science, Beijing Forestry University, Beijing, China.
Key Laboratory of Alpine Ecology, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China.
Glob Chang Biol. 2019 Oct;25(10):3438-3449. doi: 10.1111/gcb.14734. Epub 2019 Aug 1.
Changes in labile carbon (LC) pools and microbial communities are the primary factors controlling soil heterotrophic respiration (R ) in warming experiments. Warming is expected to initially increase R but studies show this increase may not be continuous or sustained. Specifically, LC and soil microbiome have been shown to contribute to the effect of extended warming on R . However, their relative contribution is unclear and this gap in knowledge causes considerable uncertainty in the prediction of carbon cycle feedbacks to climate change. In this study, we used a two-step incubation approach to reveal the relative contribution of LC limitation and soil microbial community responses in attenuating the effect that extended warming has on R . Soil samples from three Tibetan ecosystems-an alpine meadow (AM), alpine steppe (AS), and desert steppe (DS)-were exposed to a temperature gradient of 5-25°C. After an initial incubation period, soils were processed in one of two methods: (a) soils were sterilized then inoculated with parent soil microbes to assess the LC limitation effects, while controlling for microbial community responses; or (b) soil microbes from the incubations were used to inoculate sterilized parent soils to assess the microbial community effects, while controlling for LC limitation. We found both LC limitation and microbial community responses led to significant declines in R by 37% and 30%, respectively, but their relative contributions were ecosystem specific. LC limitation alone caused a greater R decrease for DS soils than AMs or ASs. Our study demonstrates that soil carbon loss due to R in Tibetan alpine soils-especially in copiotrophic soils-will be weakened by microbial community responses under short-term warming.
在变暖实验中，易变碳 (LC) 库和微生物群落的变化是控制土壤异养呼吸 (R) 的主要因素。预计变暖最初会增加 R，但研究表明，这种增加可能不是连续的或持续的。具体来说，LC 和土壤微生物群落被证明有助于扩展变暖对 R 的影响。然而，它们的相对贡献尚不清楚，这种知识空白导致对气候变化下碳循环反馈的预测存在相当大的不确定性。在这项研究中，我们使用两步培养方法来揭示 LC 限制和土壤微生物群落响应在减弱扩展变暖对 R 的影响方面的相对贡献。从三个西藏生态系统（高山草甸 (AM)、高山草原 (AS) 和沙漠草原 (DS)）采集土壤样本，暴露于 5-25°C 的温度梯度下。在初始培养期后，土壤采用以下两种方法之一进行处理：(a) 土壤进行灭菌，然后接种原始土壤微生物以评估 LC 限制效应，同时控制微生物群落响应；或 (b) 使用培养物中的土壤微生物接种灭菌的原始土壤，以评估微生物群落效应，同时控制 LC 限制。我们发现 LC 限制和微生物群落响应分别导致 R 显著下降 37%和 30%，但它们的相对贡献是生态系统特定的。LC 限制单独导致 DS 土壤的 R 下降幅度大于 AMs 或 ASs。我们的研究表明，在青藏高原土壤中，由于 R 导致的土壤碳损失——尤其是在富营养土壤中——在短期变暖下，微生物群落响应将减弱。
