Recent studies suggest that functional diversity is the driver of the positive relationship between species diversity and ecosystem function observed in numerous ecosystems.  As a result, quantifying changes in the functional diversity of communities following environmental disturbances will provide insights into how anthropogenic change will ultimately affect ecosystem function. Using two experimental sites, the Jasper Ridge Global Change Experiment and the Chronic Nitrogen Amendment study, we examined the effect of nitrogen additions on two types of mycorrhizal fungi, arbuscular mycorrhizal fungi (AMF) and ectomycorrhizal fungi (EMF).  We tested the hypothesis that increased nitrogen inputs will lead to reduced diversity of mycorrhizal fungi by taking a phylogenetic approach to infer function based on evolutionary history.  This method provides the means to quantify not only how many taxa are present, but also how divergent the taxa within a community are. 

Results/Conclusions

Experimental nitrogen additions resulted in non-random losses within both AMF and EMF communities, leading to decreases in phylogenetic diversity that were higher than predicted based on observed taxonomic losses.  In addition, community composition was significantly different when compared using both taxonomic and phylogenetic measures of community similarity.  These findings suggest that anthropogenic inputs could alter ecosystem functions by selectively eliminating taxa and functional groups within mycorrhizal communities.