Nitrogen fertilisation differentially affects the symbiotic capacity of two co-occurring ectomycorrhizal species

Forest trees are reliant on ectomycorrhizal (ECM) fungi for their health and nutrition, however, the addition of nitrogen (N) to forest soils, either intentionally or through N deposition, threatens this relationship. The mechanism of this N-related impact and how it might differentially affect diverse fungal species is not well understood. We compared the responses of two ECM species within the Pisolithus genus to N fertilisation and demonstrated that their interaction with their host was negatively affected, but through a different mechanism for each species. These results highlight the importance of ECM species composition in evaluating the impact of N addition to forest ecosystems and add to our understanding of the mechanisms driving these N impacts, allowing us to better protect ECM diversity and forest resources into the future.