Characterizing the response of fungal taxa to global change drivers

Background/Question/Methods

Anthropogenic activity in the last several centuries has resulted in a number of global change stressors which have had effects on global ecosystem compositions and activities. This has resulted in an increase of atmospheric nitrogen (N) deposition, rising global atmospheric temperature, and non-native species invasion. Previous studies at the Harvard Forest Long-term Ecological Research (LTER) site have examined the alteration of fungal community composition in response to these stressors; however, an analysis across datasets has not yet been completed. The aim of this collaborative study was to investigate and characterize the responses of individual fungal taxa to environmental change drivers across the last decade of studies on soil warming, soil N enrichment, and non-native plant invasion at Harvard Forest. Using datasets containing fungal operational taxonomic units (OTUs) identified from soil samples from sites receiving varying treatments, alpha and beta diversity changes were measured. ANOVA tests were utilized to determine significant variation in this diversity. Indicator Species Analysis was performed to test for OTUs that had statistically significant elevated frequencies in one or more of the treatments. Cohen’s d was calculated as a measure of effect size, i.e., the change in OTU relative abundance from control and experimental treatments.

Results/Conclusions

Indicator species with strong positive effect sizes varied by treatment type; for example, the nitrogen enrichment treatment had the largest number of indicator species. In addition, all indicator species were unknown beyond the family level. For diversity measures, there was significant variation of beta diversity, but not alpha diversity between control plots and two of the global change drivers, suggesting that community composition (beta diversity) is impacted by warming and nitrogen enrichment. Such results suggest that fungal communities will likely experience changes in community composition from future climate change and other anthropogenic disturbances. These results are significant because fungi serve as important ecosystem regulators, and understanding their responses to future climatic conditions can help us prepare a response to that change.