Sapling size influences shade tolerance ranking among southern boreal tree species
Article first published online: 10 NOV 2005
Journal of Ecology
Volume 94, Issue 2, pages 471–480, March 2006
How to Cite
KNEESHAW, D. D., KOBE, R. K., COATES, K. D. and MESSIER, C. (2006), Sapling size influences shade tolerance ranking among southern boreal tree species. Journal of Ecology, 94: 471–480. doi: 10.1111/j.1365-2745.2005.01070.x
- Issue published online: 10 NOV 2005
- Article first published online: 10 NOV 2005
- Received 15 March 2005 revision accepted 2 August 2005 Handling Editor: Malcolm Press
- boreal forest;
- carbon balance;
- Québec (Canada);
- radial growth;
- sapling mortality;
- shade tolerance;
- 1Traditional rankings of shade tolerance of trees make little reference to individual size. However, greater respiratory loads with increasing sapling size imply that larger individuals will be less able to tolerate shade than smaller individuals of the same species and that there may be shifts among species in shade tolerance with size.
- 2We tested this hypothesis using maximum likelihood estimation to develop individual-tree-based models of the probability of mortality as a function of recent growth rate for seven species: trembling aspen, paper birch, yellow birch, mountain maple, white spruce, balsam fir and eastern white cedar.
- 3Shade tolerance of small individuals, as quantified by risk of mortality at low growth, was mostly consistent with traditional shade tolerance rankings such that cedar > balsam fir > white spruce > yellow birch > mountain maple = paper birch > aspen.
- 4Differences in growth-dependent mortality were greatest between species in the smallest size classes. With increasing size, a reduced tolerance to shade was observed for all species except trembling aspen and thus species tended to converge in shade tolerance with size. At a given level of radial growth larger trees, apart from aspen, had a higher probability of mortality than smaller trees.
- 5Successional processes associated with shade tolerance may thus be most important in the seedling stage and decrease with ontogeny.