Species Interactions and Environmental gradients

What factors determine how tree species are distributed across a landscape? Are interactions and feedbacks between species, or species responses to the environment more important constraints on aboveground biomass? Are these feedbacks and environmental responses constant over time?

Both environmental gradients and interactions between tree species can influence the geographic distribution of different species and the total biomass stored on the landscape. Thus, our ability to forecast responses to climatic changes depends on both species responses to environmental limits, and the competitive or facilitative interactions between species.

I used a Generalized Joint Attribute Modelling (GJAM) approach to quantify past (1800’s) and modern (2000’s) species responses to environmental gradients in the US Midwest, and identify strong interactions between species that are not due to common environmental sensitivities. I show that while environmental responses are relatively conserved over time, historical land use change and loss of late successional forests removed strong species interactions that historically led to high biomass forests.