Carbohydrate storage enhances seedling shade and stress tolerance in a neotropical forest
Article first published online: 10 JAN 2007
© 2007 The Authors. Journal compilation © 2007 British Ecological Society
Journal of Ecology
Volume 95, Issue 2, pages 383–395, March 2007
How to Cite
MYERS, J. A. and KITAJIMA, K. (2007), Carbohydrate storage enhances seedling shade and stress tolerance in a neotropical forest. Journal of Ecology, 95: 383–395. doi: 10.1111/j.1365-2745.2006.01207.x
- Issue published online: 12 FEB 2007
- Article first published online: 10 JAN 2007
- Received 27 April 2006 revision accepted 10 October 2006Handling Editor: David Burslem
- carbohydrate reserve;
- carbon balance;
- growth–survival trade-off;
- life-history strategy;
- relative growth rate;
- seed size;
- seedling survival;
- shade tolerance;
- tropical forest
- 1To survive in forest understoreys, seedlings must depend on carbohydrate reserves when they experience negative carbon balance imposed by occasional light reduction and tissue loss to herbivores and diseases. We present the first experimental evidence in support of this hypothesis, using seven woody neotropical species.
- 2We transplanted seedlings that had recently expanded their first photosynthetic cotyledon or leaf to the forest understorey (1% of full sun) and quantified initial biomass and total non-structural carbohydrate (TNC) in stems, roots and storage cotyledons. We then randomly assigned seedlings to control and two stress treatments: light reduction (0.08% of full sun for 8 weeks) and complete defoliation.
- 3First-year survival of control seedlings, a comparative measure of shade tolerance, differed widely among species. The two stress treatments reduced survival and relative growth rates (RGR) of all species. Shade-tolerant species were little impacted by the stress treatments, whereas the two least shade-tolerant species experienced 100% mortality.
- 4In all treatments, 8-week and first-year survival was positively correlated with initial TNC pool size in stems and roots. By contrast, survival was generally not correlated with initial TNC concentration in any organ, TNC pools in cotyledons, seed mass or seedling biomass.
- 5TNC in stems and roots, but not in cotyledons, decreased in response to light reduction and defoliation over 8 weeks. Leaf area recovery of defoliated seedlings was positively correlated with initial TNC pools in stems and roots.
- 6First-year survival in each treatment was negatively correlated with 0–8 week RGR of control seedlings, suggesting higher stress tolerance of species with inherently slow growth rates in shade. RGR of control seedlings from 0 to 8 weeks was negatively correlated with initial TNC pools, but not concentrations, in stems and roots. After 8 weeks, RGR was positive for all species, without clear relationships with survival or TNC.
- 7We conclude that carbohydrate storage in stems and roots enhances long-term survival in shade by enabling seedlings to cope with periods of biotic and abiotic stress. Carbohydrate storage is a key functional trait that can explain species differences in growth and survival that lead to species coexistence through niche assembly processes and life-history trade-offs.