Soil Fungi in Nothofagus Forests Under Reduced Rainfall: Implications of Climate Change for Central Patagonia, Argentina

For the western Patagonia region (Argentina), climate change models predict a 1–3 °C increase in temperature and a 10%–30% reduction in precipitation. Patagonia native forests are home to a variety of soil fungi, including ectomycorrhizal fungi (EcM), which play a crucial role in drought-tolerant trees. However, the responses of soil fungi to changes in rainfall remain poorly understood. To evaluate shifts in soil fungal communities’ response under reduced precipitation scenarios and identify potentially drought-tolerant EcM species, we took 144 composite soil samples associated with Nothofagus forests along an east–west rainfall gradient. We used environmental DNA to estimate alpha and beta diversity of soil fungi and EcM. Soil fungal richness did not differ across precipitation treatments, whereas EcM richness declined with decreasing precipitation. Shannon and inverse Simpson indices of EcM decreased under reduced precipitation, whereas no significant effects were observed on soil fungi, highlighting the EcM vulnerability to water limitation. Soil fungi community composition changes along the rainfall gradient due to species replacement. Tarzetta sp., Cortinarius sp., and Russula sp. were found in drier plots, indicating a potential association with drought tolerance. Selecting native drought-tolerant EcM for forest management and restoration can improve seedling establishment and ecosystem resilience under climate change.