Interspecific demographic trade-offs and soil-related habitat associations of tree species along resource gradients
Article first published online: 12 DEC 2007
Journal of Ecology
Volume 96, Issue 1, pages 192–203, January 2008
How to Cite
Russo, S. E., Brown, P., Tan, S. and Davies, S. J. (2008), Interspecific demographic trade-offs and soil-related habitat associations of tree species along resource gradients. Journal of Ecology, 96: 192–203. doi: 10.1111/j.1365-2745.2007.01330.x
- Issue published online: 12 DEC 2007
- Article first published online: 12 DEC 2007
- Received 4 May 2007; accepted 16 October 2007; Handling Editor: Charles Canham
Vol. 96, Issue 6, 1330, Article first published online: 24 SEP 2008
- edaphic gradient;
- growth rate;
- life-history trade-offs;
- mixed dipterocarp forest;
- mortality rate;
- soil resources;
- tree demography;
- tropical rain forest
- 1Interspecific relationships between fundamental demographic rates, often called demographic trade-offs, emerge from constraints within individuals related to morphology, physiology and resource allocation. Plant species that grow fast in high light usually have high mortality in shade, and this well-established relationship in part defines a species’ successional niche. More generally, this relationship represents a trade-off between a species’ ability to grow quickly to exploit abundant resources vs. avoiding mortality when resources are less plentiful, but few studies have described this demographic trade-off with respect to environmental factors other than light.
- 2Using demographic data from 960 tree species in Bornean rain forest, we examined the evidence for an interspecific demographic trade-off between fast growth and low mortality and its variation among habitats defined by variation in soil fertility and moisture. Such a trade-off could contribute to sorting of tree species among habitats and partly explain the striking patterns of species’ edaphic associations in this and other forests.
- 3We found strong evidence for this demographic trade-off, both within the same habitat and when growth on edaphically rich habitats was compared with mortality on a habitat with lower below-ground resource availability.
- 4The slope of the growth-mortality relationship varied among habitats, being steepest on the habitat lowest in below-ground resources. For species with the fastest potential growth rates, mortality was higher on this habitat than at comparable growth rates on the three more edaphically rich habitats, providing a possible mechanism by which fast-growing species may be eliminated from the poorest habitat. Adaptations for fast growth may entail a greater mortality risk, if inherently fast-growing species fail to maintain a positive C-balance when below-ground resources are scarce.
- 5Conversely, for species with the slowest potential growth rates, the highest species’ mortality rates occurred on the habitats with greatest below-ground resource availability, implying that slow-growing species may have a competitive disadvantage in resource-rich environments.
- 6Synthesis. Differences among habitats in the steepness of this trade-off may sort species into different habitats along this edaphic gradient, whereas on the same soil, this demographic trade-off could facilitate coexistence of at least some species in this forest. Thus, by generating emergent demographic trade-offs that vary along resource gradients, plant life-history strategies can influence species diversity and distribution.