Soil fungal community drives ecosystem multifunctionality: Variations across the Sub-, Low- and High Arctic

Xinyu Xu, Shunsuke Matsuoka, Keita Nishizawa, Shu Kuan Wong, Masaki Uchida, Akira S. Mori

Soil fungal communities support multiple ecosystem functions, including carbon sequestration, nutrient cycling, and parasite resistance. However, it still remains unclear whether and how soil fungal diversity and community composition drive ecosystem multifunctionality—the capacity of an ecosystem to simultaneously sustain multiple functions and services—particularly in the Arctic, an extremely vulnerable region with vast carbon reserves. Here, based on a series of surveys and soil sampling across the Sub-, Low-, and High Arctic, we examined the role of soil fungal diversity and composition in maintaining ecosystem multifunctionality and investigated the factors that mediate these contributions. High-throughput sequencing with LSU region and the GeoChip 5.0 M was used to identify the taxonomic and functional fungal community, respectively. Soil physical and chemical properties were determined, and plant composition and relative coverage were estimated. Multifunctionality was calculated based on 10 indicator variables of ecosystem functions, using the method of normalized average, multi-threshold and Hill-Chao numbers. We found a positive relationship between fungal diversity and ecosystem multifunctionality across three Arctic regions, and such a relationship was more pronounced in the High Arctic. The composition of fungal communities significantly impacted ecosystem multifunctionality, with this relationship being most robust in the High Arctic. Furthermore, the soil temperature was detected as a key factor regulating the contribution of soil fungal communities to ecosystem multifunctionality across the Arctic. Our findings suggest that the effects of diversity loss and community compositing shifts are more profound in vulnerable regions under greater cold stress in the Arctic.