Combining distributed ecology with phylogenetics to understand global change: Lessons from the Nutrient Network
Responses of plant communities to anthropogenic global change will depend on individual species responses, which in turn are informed by both ecological interactions and evolutionary constraints. Predicting these changes requires a general understanding of both ecological and evolutionary influences on plant response to changes such as eutrophication or alteration of herbivory regimes. We combined plot-level observations from the Nutrient Network distributed experiment conducted at 59 grassland sites in 15 countries, with an assembled phylogeny for over 1500 species to examine the strength of evolutionary influence on how plant species respond to nutrient addition and exclusion of vertebrate herbivores. Specifically, we analyzed changes in abundance following treatments to separate clades in which responses were more conserved from those in which traits were more labile.
Plant species responses to different treatments varied from phylogenetically conserved to highly labile in response to the experimental treatments. For example, species’ changes in abundance in response to nitrogen and phosphorus addition were labile across and within clades The acquisition of these limiting nutrients is thought to be controlled by similarly evolutionarily labile functional traits. In contrast, species’ responses to the addition of potassium, sulfur, and other micronutrients were phylogenetically conserved and concentrated in specific clades. The response of plant species to removal of vertebrate herbivory also was significantly phylogenetically structured, emphasizing the importance of evolutionary history in predicting trophic interactions. The unique insights acquired here are made possible by two major advances represented in our approach: distributed experimentation and advances in phylogenetic systematics. The distributed experimental approach is generalizable to other important ecological questions.