Research was supported by the Center for Tropical Forest Science – Arnold Arboretum Asia Program, a CTFS research grant and a postdoctoral fellowship to J. L. B. from the Natural Science and Engineering Research Council of Canada.
Rainfall seasonality and pest pressure as determinants of tropical tree species' distributions
Article first published online: 27 SEP 2012
© 2012 The Authors. Ecology and Evolution published by Blackwell Publishing Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Ecology and Evolution
Volume 2, Issue 11, pages 2682–2694, November 2012
How to Cite
Ecology and Evolution 2012; 2(11): 2682–2694
- Issue published online: 8 NOV 2012
- Article first published online: 27 SEP 2012
- Manuscript Accepted: 27 AUG 2012
- Manuscript Revised: 17 AUG 2012
- Manuscript Received: 14 JUN 2012
- Center for Tropical Forest Science
- Natural Science and Engineering Research Council of Canada
- global change;
- Kangar-Pattani Line;
- species distributions;
- tropical forests
Drought and pests are primary abiotic and biotic factors proposed as selective filters acting on species distributions along rainfall gradients in tropical forests and may contribute importantly to species distributional limits, performance, and diversity gradients. Recent research demonstrates linkages between species distributions along rainfall gradients and physiological drought tolerance; corresponding experimental examinations of the contribution of pest pressure to distributional limits and potential interactions between drought and herbivory are limited. This study aims to quantitate differential performance and herbivory as a function of species range limits across a climatic and floristic transition in Southeast Asia. Khao Chong Botanical Garden, Thailand and Pasoh Forest Reserve, Malaysia straddle the Kangar-Pattani Line. A reciprocal transplantation across a seasonality gradient was established using two groups of species (“widespread” taxa whose distributions include seasonally dry forests and “aseasonal” taxa whose distributions are limited to aseasonal forests). Growth, biomass allocation, survival, and herbivory were monitored for 19 months. Systematic differences in performance were a function of species distribution in relation to rainfall seasonality. In aseasonal Pasoh, aseasonal species had both greater growth and survivorship than widespread species. These differences were not a function of differential herbivory as widespread and aseasonal species experienced similar damage in the aseasonal forest. In seasonally dry Khao Chong, widespread species showed higher survivorship than aseasonal species, but these differences were only apparent during drought. We link this differential performance to physiological mechanisms as well as differential tolerance of biotic pressure during drought stress. Systematic decreases in seedling survival in aseasonal taxa during drought corresponded with previously documented physiological differences and may be exacerbated by herbivore damage. These results have important implications for tropical diversity and community composition in light of predicted increases in the frequency and severity of drought in hyperdiverse tropical forests.