Increased snow and cold season temperatures alter High Arctic parasitic fungi – host plant interactions

In the Arctic, fungal mycelial growth takes place mainly during cold season and beginning of growing season. Climate change induced increases temperatures may, hence, benefit increase their abundance. This is particular importance for parasitic fungi, which may significantly shape Arctic vegetation composition. Here, we studied two contrasting plant fungi’s occurrences (biotrophic Exobasidium hypogenum Nannf. on vascular Cassiope tetragona (L.) D. Don., necrotrophic Pythium polare Tojo, van West & Hoshino moss Sanionia uncinata (Hedw.) Loeske) in response to increased snow depth, a method primarily used temperatures, after 7–13 years manipulation Adventdalen, Svalbard. We show that enhanced depth both fungi tested here indicate infections host plants were at least partly responsible decreases occurrences. Although bryophyte growth, general, be influenced by soil moisture reduced competition from plants, likely combination milder winter moister environment provided snow. The relationships between infection ongoing processes involved dynamics compositional adjustment changing climate.