Journal of Tropical Ecology



The relative roles of environment, history and local dispersal in controlling the distributions of common tree and shrub species in a tropical forest landscape, Panama


Jens-Christian Svenning a1a2c1, Bettina M. J. Engelbrecht a2a3, David A. Kinner a4, Thomas A. Kursar a2a5, Robert F. Stallard a2a6 and S. Joseph Wright a2
a1 Department of Biological Sciences, University of Aarhus, DK-8000 Aarhus C., Denmark
a2 Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panamá
a3 Department of Plant Ecology and Systematics, University of Kaiserslautern, 67653 Kaiserslautern, Germany
a4 Central Region Geologic Hazards Team, U.S. Geological Survey, Box 25046 DFC, Mail Stop 966, Denver, CO 80225, USA
a5 Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
a6 U.S. Geological Survey, 3215 Marine St E127, Boulder, CO 80303-1066, USA

Article author query
svenning j   [PubMed][Google Scholar] 
engelbrecht bm   [PubMed][Google Scholar] 
kinner da   [PubMed][Google Scholar] 
kursar ta   [PubMed][Google Scholar] 
stallard rf   [PubMed][Google Scholar] 
wright sj   [PubMed][Google Scholar] 

Abstract

We used regression models and information-theoretic model selection to assess the relative importance of environment, local dispersal and historical contingency as controls of the distributions of 26 common plant species in tropical forest on Barro Colorado Island (BCI), Panama. We censused eighty-eight 0.09-ha plots scattered across the landscape. Environmental control, local dispersal and historical contingency were represented by environmental variables (soil moisture, slope, soil type, distance to shore, old-forest presence), a spatial autoregressive parameter (ρ), and four spatial trend variables, respectively. We built regression models, representing all combinations of the three hypotheses, for each species. The probability that the best model included the environmental variables, spatial trend variables and ρ averaged 33%, 64% and 50% across the study species, respectively. The environmental variables, spatial trend variables, ρ, and a simple intercept model received the strongest support for 4, 15, 5 and 2 species, respectively. Comparing the model results to information on species traits showed that species with strong spatial trends produced few and heavy diaspores, while species with strong soil moisture relationships were particularly drought-sensitive. In conclusion, history and local dispersal appeared to be the dominant controls of the distributions of common plant species on BCI.

(Published Online July 27 2006)
(Accepted February 6 2006)


Key Words: Barro Colorado Island; dispersal limitation; drought tolerance; environmental control; soil.

Correspondence:
c1 Corresponding author. Email: svenning@biology.au.dk