There is no understanding of the present without understanding the past. This is particularly true when the majority of the historical biogeographical setting is substantially different than the present situation. Even the most long-term ecological studies of existing rainforest communities, lasting for decades, capture the tiniest fraction of their overall history. Through the creation of dynamic computer simulations, bringing together paleoclimate models, historical land area, and parameters for vegetation response, we are examining the macroevolutionary landscape through the last ice age and using these findings to project back over the Quaternary Period.
Download our recent publication in PNAS here
Four scenarios for the distribution of forests at the Last Glacial Maximum
Our first publication on this topic came out in PNAS (see link above for publication) recently. We produced some neat animations of the distribution of evergreen rainforests over the last glacial cycle (0-120,000 years ago) available as supplementary material. These are worth watching, as the transition during the flooding of the South China Sea roughly 12,000 years ago is quite amazing. The results clearly indicate the familiar ‘island archipelago’, consisting of Borneo, Java, and Sumatra, is extremely unusual, at two time scales (over the last glacial cycle or over the last million years). In comparison to the north temperate zone, where forests went through a major expansion at the end of the last ice age, the forests of Southeast Asia went through a major contraction and fragmentation event, primarily due to the rise in sea levels. These dynamics also differed substantially for the major forest types found in the region.
There are several projects which could extend out of this research:
1) modeling of species distributions based on assumptions about dispersal mechanisms and environmental niche.
2) the natural formation of refugia. Is it a truncation process, where the core of the refugium is already saturated and highly resistant to invasion, or is it a reabsorption process, where diversity spread over a much larger geographic area becomes highly concentrated in the refugium.
3) test the various hypotheses about historical population sizes proposed by the model for the different vegetation zones.
Lowland evergreen rainforest over the last million years, given three scenarios at two different assumptions about temperature change
