HoangLuu.com - My Research

Changes to forests take many years to transpire and running experiments on a forest to test an ecological theory isn’t practical. It would be great to test the effects of global climate change on a forest before climate change happens. Such a test would give hard evidence on how climate change will impact our forests, but that currently isn’t possible. Using models that are reflective of forest dynamics is currently the best tool that we have to explore forest dynamics.

Individual-based models have been used to understand how seemingly small individual interactions can influence large-scale ecosystem dynamics. Predator-prey models that explore hypothetical individual predation and reproductive values of an ecosystem are one example. Forest gap models are a class of the individual-based model that simulate the recruitment, growth, and death of trees. Advances in science and technology lead to more computationally complex models that would include the inter-and intra-specific competition and disturbances. Many of the forest gap models have scaled up to a global level and have served as excellent tools to predict how climate change affects our global forests.

One of the biggest assumptions made by many of these models is how recruitment occurs. A lot of models use the idea of “sapling rain” where it is assumed that the seeds of every potential tree are always present. Thus, it ignores the variation in seed production and establishment in the forest. Climate and the size/age of a tree influence the fecundity of an individual and omitting that interaction can lead to wrong forest projections. The current commonly used framework in these models doesn’t have a connection between mature trees and the seeds that they produce. One of the goals of my graduate research is to update how recruitment is presented in the models by adding seeds into the framework. Mature trees will produce seeds, those seeds will establish into seedlings, the seedlings will become saplings, those saplings become mature trees, and the cycle continues.

Empirical data is publicly available and will be used to create the fecundity and establishment functions. Once implemented into a model, we can then answer how reproduction will influence forest dynamics? How will climate change and our management activities affect those forest dynamics with and without the new framework for modeling recruitment?