Department of Earth Science, University of Gothenburg, Gothenburg, Sweden.
Isotope Bioscience Laboratory (ISOFYS), Department of Green Chemistry and Technology, Ghent University, Ghent, Belgium.
Mycorrhiza. 2022 Jul;32(3-4):305-313. doi: 10.1007/s00572-022-01075-4. Epub 2022 Mar 21.
The soil nitrogen (N) cycle in cold terrestrial ecosystems is slow and organically bound N is an important source of N for plants in these ecosystems. Many plant species can take up free amino acids from these infertile soils, either directly or indirectly via their mycorrhizal fungi. We hypothesized that plant community changes and local plant community differences will alter the soil free amino acid pool and composition; and that long-term warming could enhance this effect. To test this, we studied the composition of extractable free amino acids at five separate heath, meadow, and bog locations in subarctic and alpine Scandinavia, with long-term (13 to 24 years) warming manipulations. The plant communities all included a mixture of ecto-, ericoid-, and arbuscular mycorrhizal plant species. Vegetation dominated by grasses and forbs with arbuscular and non-mycorrhizal associations showed highest soil free amino acid content, distinguishing them from the sites dominated by shrubs with ecto- and ericoid-mycorrhizal associations. Warming increased shrub and decreased moss cover at two sites, and by using redundancy analysis, we found that altered soil free amino acid composition was related to this plant cover change. From this, we conclude that the mycorrhizal type is important in controlling soil N cycling and that expansion of shrubs with ectomycorrhiza (and to some extent ericoid mycorrhiza) can help retain N within the ecosystems by tightening the N cycle.
寒冷陆地生态系统中的土壤氮（N）循环缓慢，有机结合态 N 是这些生态系统中植物 N 的重要来源。许多植物物种可以直接或间接地通过其菌根真菌从这些贫瘠的土壤中吸收游离氨基酸。我们假设植物群落的变化和当地植物群落的差异会改变土壤游离氨基酸库和组成；长期变暖可能会增强这种效应。为了验证这一点，我们在斯堪的纳维亚亚北极和高山的五个不同的石南、草地和沼泽地地点研究了可提取游离氨基酸的组成，这些地点都进行了长期（13 至 24 年）的变暖处理。植物群落都包含了外生菌根、内生菌根和丛枝菌根植物的混合物。以具有丛枝和非菌根关系的禾本科和草本植物为主的植被具有最高的土壤游离氨基酸含量，这使它们与以具有外生菌根和内生菌根关系的灌木为主的地点区分开来。在两个地点，变暖增加了灌木而减少了苔藓的覆盖，通过冗余分析，我们发现土壤游离氨基酸组成的改变与这种植物覆盖的变化有关。由此我们得出结论，菌根类型在控制土壤 N 循环中很重要，外生菌根（在某种程度上还有内生菌根）灌木的扩张可以通过收紧 N 循环来帮助保留生态系统中的 N。
