Species assembly in vegetation under a changing climate: plant traits, contested resources, and community consequences

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A fundamental goal for conservation and restoration ecology is to understand the mechanisms that explain why the species richness and productivity of vegetation are greater in some places than in others. Answers to this question are essential for making informed predictions and recommendations associated with vegetation response to rapid climate change. In the first major component of my research program, I will explore a new way of thinking about competitive ability in plants - one that recognizes that fitness under competition involves more than just growth (plant size) and survival; it also involves, most importantly, producing offspring. Projects will examine how the deployment and allocation of plant meristems / buds affects all three components of fitness under competition - plant size, survival and fecundity, and they will test predictions about how these can be used to define a theory for the coexistence of many species without requiring that they compete weakly, and without requiring a heterogeneous physical environment. In the second component of my research program, the above multi-trait-based approach to plant competitive ability will be tested in the specific context of competition for water using resource manipulation experiments within long-term field plots in natural vegetation along environmental gradients. On a world-wide scale, water is the most significant limiting resource and object of competition in cropping systems. Forecasters predict that, because of climate change and other anthropogenic effects, concerns for water supply in the 21st century will be what oil supply was in the last century. I predict that water is the most limiting resource affecting plant competition and plant community structure and assembly even in non-arid environments, yet the vast majority of studies and theory in vegetation ecology emphasize competition for light and nutrients as the most important objects of competition and limitation on biomass production in natural vegetation. This research program will address this imbalance.