DRY4: Incorporating seasonally and spatially dynamic ectomycorrhizal fungal communities strengthens predictions of soil biogeochemical cycling in neotropical dry forests

Ectomycorrhizal (ECM) symbioses support forest functioning globally, yet both the structure and function of ECM fungal communities in seasonally neotropical deciduous forests (STDF), known for extreme heterogeneity in vegetation and edaphic properties, remains under characterized.Here we evaluated the relative influences of seasonal versus spatial variation in ECM fungal community structure in four SDTFs. We also identified environmental drivers of STDF ECM fungal community structure and assessed ectomycorrhizal effects on soil carbon (C) and nitrogen (N).ECM fungal abundance and richness increased in the wet season, but spatial rather than seasonal effects explained more variation in community composition. Tree community differences drove ECM community turnover across SDTFs. Although soil moisture and ECM tree basal area were stronger predictors of soil biogeochemistry, incorporating ECM fungal community metrics added explanatory power to models of soil C and N cycling in the wet season.These results highlight the importance of SDTF plant communities in shaping ECM fungal communities and the potential for both the plant and fungal components of ECM symbioses to impact soil functioning. Our findings suggest that alterations in SDTF plant community composition due to climate or land-use change will have important consequences for ECM fungal diversity and soil biogeochemical cycling.