There is much interest in understanding how broad-scale patterns and dynamics emerge from the individual components that make up complex ecosystems. Of particular interest is whether an approach centered upon species traits, or trait combinations, can provide the needed link between individual species-specific characteristics and emergent dynamics at the ecosystem scale. Alternatively, ecosystem dynamics may be governed by macroscopic ecosystem properties (e.g., plant productivity, competition for light and resources, or disturbance agents) and that individual traits adapt to these ecosystem constraints rather than generate them. A third hypothesis is that both explanations apply and, in cases, can interact to form feedbacks that hold particular power to influence emergent ecosystem properties across the land biosphere. We will here address these three alternative hypotheses using a combination of observations and datasets from ecosystems across the land biosphere, and a new family of models that we are developing to evaluate the interaction between plant traits, plant strategies and the emergence of patterns and dynamics at the ecosystem scale.
Results/Conclusions
By focusing on a class of traits that includes symbiotic nitrogen fixation, we will show that simple evolution-based models can resolve some of the most fundamental (and previously unresolved) global patterns in forest nutrient cycling and in successional dynamics and plant-plant competition across biomes. The most parsimonious result is that, for a certain class of traits, there is a high likelihood that individual-ecosystem feedbacks emerge, and that these can transform properties at the ecosystem scale, but also form the template within which plant traits assemble and evolve. We will discuss the limits to this analysis and to our current ability to probe for traits that have disproportionate influences on ecosystem function and dynamics.