Climate change, regionally exacerbated by deforestation, could result in the transformation of evergreen rain forests into seasonal savanna-type vegetation, changing biogeochemical cycles and compromising ecosystem services. The impacts of 14 years of partial rainfall exclusion on soil fungal functional diversity and extracellular enzyme activities (EEA) were related to ecosystem carbon and nutrient dynamics in Amazonia. Soil samples collected in the rainy and dry seasons in 2016 from the rainfall exclusion experiment and a paired control plot, both established in 2002, were analysed for EEA and for soil fungal community composition.
Results/Conclusions
We report increases in fungal diversity in response to drought and striking changes in functional groups. There was a conspicuous increase in dark-septate fungi, likely related to water regulation under moisture stress with the effect of enhancing ecosystem resilience. Nutrient cycling also changed, as indicated by EEA data, from an apparent phosphorus and carbon limitation under natural precipitation seasonality to nitrogen limitation under long-term experimental drought. The high seasonality of EEA in the non-droughted control forest and its substantial suppression in the drought treatment may be an indication of the ecosystem operating at its limits in terms of functional adaptability under long-term soil drought.