Research initiated by the Center for Tropical Forest Science, a joint program of the Arnold Arboretum and the Smithsonian Institution, reveals that the structure and dynamics of many tropical forests are changing, though uncertainty still surrounds the causes and consequences of these changes. In a study published in Ecology, the journal of the American Ecological Society, scientists investigated shifts in tree species composition over the past 25 years within the 50-hectare Forest Dynamics Plot that CTFS maintains on Barro Colorado Island (BCI), Panama. The study examined how observed patterns relate to predictions of random population fluctuations, carbon fertilization, succession from past disturbance, recovery from an extreme El Nĩno drought at the start of the study period, and long-term climate change.
Data analyzed in the study suggest that there have been consistent and directional changes in the tree species composition at BCI, characterized by increased relative representations of drought-tolerant species. These fluctuations in forest composition may be the legacy of the El Nĩno drought, or alternatively, potentially reflect increased aridity due to long-term climate change. This investigation of forest compositional changes enhances our understanding of the ecology of tropical forests and their responses to large-scale disturbances, and informs predictions for how future global change will impact some of the critical services provided by these important ecosystems.
The results of the study appear as the cover story in the April, 2011 issue of Ecology (Vol. 92, No. 4). The paper is co-authored by Arnold Arboretum Director of Asia Programs Stuart J. Davies, with Kenneth Feeley (Florida International University and Fairchild Tropical Botanic Garden), Rolando Perez (CTFS), Stephen Hubbell (CTFS and University of California–Los Angeles), and Robin Foster (Field Museum, Chicago).
Feeley, K. J., S. J. Davies, R. Perez, S. P. Hubbell, and R. B. Foster. 2011. Directional changes in the species composition of a tropical forest. Ecology 92(4): 871-882. [pdf]