Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Key Laboratory of Crop Gene Resources and Germplasm Enhancement in Southern China, Ministry of Agriculture, Danzhou, Hainan, China.
Glob Chang Biol. 2021 May;27(10):2061-2075. doi: 10.1111/gcb.15553. Epub 2021 Feb 27.
Soil microbes are directly involved in soil organic carbon (SOC) decomposition, yet the importance of microbial biodiversity in regulating the temperature sensitivity of SOC decomposition remains elusive, particularly in alpine regions where climate change is predicted to strongly affect SOC dynamics and ecosystem stability. Here we collected topsoil and subsoil samples along an elevational gradient on the southeastern Tibetan Plateau to explore the temperature sensitivity (Q ) of SOC decomposition in relation to changes in microbial communities. Specifically, we tested whether the decomposition of SOC would be more sensitive to warming when microbial diversity is low. The estimated Q value ranged from 1.28 to 1.68, and 1.80 to 2.10 in the topsoil and subsoil, respectively. The highest Q value was observed at the lowest altitude of forests in the topsoil, and at the highest altitude of alpine meadow in the subsoil. Variations in Q were closely related to changes in microbial properties. In the topsoil the ratio of gram-positive to gram-negative bacteria (G+:G-) was the predominant factor associated with the altitudinal variations in Q . In the subsoil, SOC decomposition showed more resilience to warming when the diversity of soil bacteria (both whole community and major groups) and fungi was higher. Our results partly support the positive biodiversity-ecosystem stability hypothesis. Structural equation modeling further indicates that variations in Q in the subsoil were directly related to changes in microbial diversity and community composition, which were affected by soil pH. Collectively our results provide compelling evidence that microbial biodiversity plays an important role in stabilizing SOC decomposition in the subsoil of alpine montane ecosystems. Conservation of belowground biodiversity is therefore of great importance in maintaining the stability of ecosystem processes under climate change in high-elevation regions of the Tibetan Plateau.
土壤微生物直接参与土壤有机碳（SOC）分解，但微生物生物多样性在调节 SOC 分解的温度敏感性方面的重要性仍不清楚，特别是在预测气候变化将强烈影响 SOC 动态和生态系统稳定性的高山地区。在这里，我们沿着青藏高原东南部的海拔梯度收集了表土和底土样本，以探索 SOC 分解的温度敏感性（Q）与微生物群落变化的关系。具体来说，我们测试了当微生物多样性较低时，SOC 的分解是否会对变暖更敏感。估计的 Q 值在表土和底土中分别为 1.28 至 1.68 和 1.80 至 2.10。在表土中森林的最低海拔处观察到最高的 Q 值，在底土中高山草甸的最高海拔处观察到最高的 Q 值。Q 的变化与微生物特性的变化密切相关。在表土中，革兰氏阳性菌与革兰氏阴性菌（G+：G-）的比例是与 Q 的海拔变化相关的主要因素。在底土中，当土壤细菌（整个群落和主要类群）和真菌的多样性较高时，SOC 分解对变暖的抵抗力更强。我们的结果部分支持正生物多样性-生态系统稳定性假说。结构方程模型进一步表明，底土中 Q 的变化与微生物多样性和群落组成的变化直接相关，而微生物多样性和群落组成的变化受土壤 pH 值的影响。总的来说，我们的结果提供了令人信服的证据，证明微生物生物多样性在稳定高山山地生态系统底土 SOC 分解方面发挥着重要作用。因此，在青藏高原高海拔地区，保护地下生物多样性对于维持生态系统过程的稳定性在气候变化下具有重要意义。
