COS 56-8
Stoichiometric homeostasis underlies species dominance, stability and responses to global change
Stoichiometric homeostasis (H) refers to the degree to which an organism maintains elemental concentrations or ratios within tissues despite variation in the relative availabilities of elements in its resource supplies, which ultimately reflects underlying physiological and biochemical allocations as organisms respond to their surrounding environments. Ecological theory predicts that species with high H should dominate communities and confer greater temporal stability, and regulate species response to climate change. In this study, we will focus on three scientific questions. First, is high H related to high species dominance and stability in a highly productive tallgrass prairie system? Previous research supporting H as a key plant trait has been limited low productivity grasslands. Second, are differential responses of plant species to N additions related to H? Third, is H predictive of species responses to alterations in water availability? We estimated H of 11 common species in a North American tallgrass prairie and assessed the relationships between H and species dominance and temporal stability based on long-term community composition data from the Long-Term Ecological Research (LTER) program at the Konza Prairie Biological Station. We then evaluated how long-term N addition altered the relationship between H and species dominance. Finally, we determined how three species with different H values responded to short and long-term precipitation manipulation experiments.
Results/Conclusions
Analysis of 25-yrs of plant community composition data from a central US grassland showed H was positively correlated with both species-level abundance and temporal stability. Relationships between H, species dominance and stability were strong in the graminoids but not for the forbs. Here we show that consequences of differences among species in H also may extend to responses to global change – based on both short and long-term N and water manipulation experiments conducted in the same grassland. In a 10-yr chronic nitrogen (N) deposition experiment, species with high H maintained their dominance during the initial 5 years, but as predicted by theory, species with low H eventually increased. However, in climate change experiments that varied from 2- yrs of extreme drought, 10-yrs of altered precipitation patterns, and 20-yrs of irrigation, species with the highest H were the least responsive to changes in this resource. The temporal stability of species with high H in this range of precipitation manipulation experiments suggest that H, or additional traits correlated with H, may play a broader role in determining ecosystem responses to global changes drivers.