Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, Zurich, Switzerland.
AMAP (botAnique et Modélisation de l'Architecture des Plantes et des végétations), Université de Montpellier, CIRAD, CNRS, INRAE, IRD, Montpellier, France.
Nat Ecol Evol. 2022 Apr;6(4):375-382. doi: 10.1038/s41559-022-01663-9. Epub 2022 Feb 24.
Most trees on Earth form a symbiosis with either arbuscular mycorrhizal or ectomycorrhizal fungi. By forming common mycorrhizal networks, actively modifying the soil environment and other ecological mechanisms, these contrasting symbioses may generate positive feedbacks that favour their own mycorrhizal strategy (that is, the con-mycorrhizal strategy) at the expense of the alternative strategy. Positive con-mycorrhizal feedbacks set the stage for alternative stable states of forests and their fungi, where the presence of different forest mycorrhizal strategies is determined not only by external environmental conditions but also mycorrhiza-mediated feedbacks embedded within the forest ecosystem. Here, we test this hypothesis using thousands of US forest inventory sites to show that arbuscular and ectomycorrhizal tree recruitment and survival exhibit positive con-mycorrhizal density dependence. Data-driven simulations show that these positive feedbacks are sufficient in magnitude to generate and maintain alternative stable states of the forest mycobiome. Given the links between forest mycorrhizal strategy and carbon sequestration potential, the presence of mycorrhizal-mediated alternative stable states affects how we forecast forest composition, carbon sequestration and terrestrial climate feedbacks.
地球上大多数树木与丛枝菌根真菌或外生菌根真菌形成共生关系。通过形成共同的菌根网络，主动改变土壤环境和其他生态机制，这些对比鲜明的共生关系可能会产生正反馈，以牺牲替代策略为代价，有利于它们自己的菌根策略（即共菌根策略）。正的共菌根反馈为森林及其真菌的替代稳定状态奠定了基础，在这种状态下，不同的森林菌根策略的存在不仅取决于外部环境条件，还取决于森林生态系统中嵌入的菌根介导的反馈。在这里，我们使用数千个美国森林清查点来检验这一假设，结果表明，丛枝菌根和外生菌根树木的繁殖和存活表现出正的共菌根密度依赖性。数据驱动的模拟表明，这些正反馈的强度足以产生和维持森林菌根生物群的替代稳定状态。鉴于森林菌根策略与碳封存潜力之间的联系，菌根介导的替代稳定状态的存在影响我们预测森林组成、碳封存和陆地气候反馈的方式。
