Research

Maintenance of biodiversity

How can so many tree species occur in tropical forests? Do they coexist stably or are they subject to neutral dynamics? I suspect that, in such species-rich systems, fitness equalizing mechanisms are the strongest driver of species maintenance. An evidence is the explanatory power neutral theory has to predict diversity patterns and dynamics on these forests. As tropical forest trees are most limited by light, I focus on trade-offs that may reduce fitness differences between species, such as the light aquisition - light use trade-off. Because most species regenerate in the shade, I restricted my sampling to shade-tolerant treelets and saplings of taller species that are found in the understory of a Central Amazon forest in Brazil. Preliminary results show that: 1) position along this trade-off can be predicted by adult size; and 2) departure from the trade-off can explain species abundance in the forest.

Evolution of plant architecture

In Amazon, I found distantly related tree species showing very similar growth strategies as well as clades that have conserved their architectural archetypes. My idea is to delve into this question initially by describing how crown architecture has evolved in Amazonian trees, and then testing what traits might be responsible for these patterns. Specifically, I want to test the old idea that leaf traits such as leaf size may constitute evolutionary constraints to the transition from one type of architecture to another. Additionally, I plan to analyze whether stem density, a phylogenetically conserved trait that may drastically change the carbon budget of a given architectural type, also has limited the evolvability of architecture in certain lineages.

Species distributions

What determines species distributions across the landscape? Why are there species constrained to certain habitats (specialists), while others seem to occur everywhere (generalists)? Why don't specialists, at their home habitats, exclude generalists? I think the key to answering these questions lies on demographic trade-offs, specifically on how they change across the landscape. I will be focusing at the relationship between growth and mortality rates of tree species and how it changes across topographic gradients in tropical forests. I also plan to test whether traits related to growth rates can predict the degree of habitat specialization of the studied species.