Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, Uppsala, 750 07, Sweden.
Department of Biology, University of Copenhagen, Copenhagen, 2100, Denmark.
Ecol Lett. 2021 Jun;24(6):1193-1204. doi: 10.1111/ele.13735. Epub 2021 Mar 22.
Tundra ecosystems are global belowground sinks for atmospheric CO . Ongoing warming-induced encroachment by shrubs and trees risks turning this sink into a CO source, resulting in a positive feedback on climate warming. To advance mechanistic understanding of how shifts in mycorrhizal types affect long-term carbon (C) and nitrogen (N) stocks, we studied small-scale soil depth profiles of fungal communities and C-N dynamics across a subarctic-alpine forest-heath vegetation gradient. Belowground organic stocks decreased abruptly at the transition from heath to forest, linked to the presence of certain tree-associated ectomycorrhizal fungi that contribute to decomposition when mining N from organic matter. In contrast, ericoid mycorrhizal plants and fungi were associated with organic matter accumulation and slow decomposition. If climatic controls on arctic-alpine forest lines are relaxed, increased decomposition will likely outbalance increased plant productivity, decreasing the overall C sink capacity of displaced tundra.
苔原生态系统是全球地下 CO 的汇。灌木和树木的持续增温入侵，可能会使这个汇变成 CO 的源，从而对气候变暖产生正反馈。为了深入了解菌根类型的变化如何影响长期的碳 (C) 和氮 (N) 储量，我们研究了亚北极高山森林-石南植被梯度上真菌群落和 C-N 动态的小尺度土壤深度剖面。从石南到森林的过渡地带，地下有机储量突然减少，这与某些与树木相关的外生菌根真菌的存在有关，当它们从有机物中提取 N 时，这些真菌有助于分解。相比之下，杜鹃花菌根植物和真菌与有机物积累和缓慢分解有关。如果对北极高山森林线的气候控制放宽，那么增加的分解可能会超过植物生产力的增加，从而降低被取代的苔原生态系统的整体碳汇能力。
