Interannual variation in competitive interactions from natural and anthropogenic disturbances in a temperate forest tree species: Implications for ecological interpretation

Hartmann, Henrik et Messier, Christian (2011). « Interannual variation in competitive interactions from natural and anthropogenic disturbances in a temperate forest tree species: Implications for ecological interpretation ». Forest Ecology and Management, 261, pp. 1936-1944.

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Résumé

Competition is a major determinant of plant growth and is often used in studies of tree growth and species coexistence. However, these approaches are usually temporally static, i.e., assessed at a single point or period in time. While constantly changing forest conditions due to natural and human-induced disturbances potentially alter competition among individuals, static approaches cannot qualify the temporal variability of competitive interactions. Herewepresent a longitudinal analysis of competitive interactions among trees and discuss the implication of our results for ecological interpretation. Spatially-explicit tree growth data were obtained from 18 study plots (0.4 ha each) in sugar maple (Acer saccharum Marsh.) stands in Quebec, Canada. During the studied period (1980–2003), these stands had been disturbed by insect outbreaks (forest tent caterpillar, Malacosoma disstria Hubner) and by commercial partial harvest. We analyzed radial growth rates (outcome of competition) on an annual basis and as a function of tree biology (bole diameter, crown position), competition (above- and belowground competition from neighbours) and environmental conditions (light availability, harvest disturbance). Competitive interactions changed throughout the studied period. Canopy disturbance from partial harvest interacted with defoliators and influenced competition symmetry by favoring smaller trees. Competitive interactions seemed to have switched from below- to above-ground following canopy recovery after harvest. Release from competition due to partial harvest increase neighbourhood size (radius of effective competition) and enhanced the competitive pressure from larger individuals. The temporal variability in parameter estimates may be used for setting confidence intervals on competitive success (growth rates), thereby yielding a more robust basis for ecological interpretation. Our results also show that temporal variability in competitive interactions could contribute to the maintenance of high tree species diversity and structural complexity in some ecosystems by temporally altering species-specific responses to environmental change and disturbance.

Type:	Article de revue scientifique
Mots-clés ou Sujets:	Acer saccharum, Competition–growth relationship, Ecological interpretation, Temporal variation, Disturbance, Light environment, Above-ground competition, Species coexistence
Unité d'appartenance:	Centres institutionnels > Centre d'étude de la forêt (CEF) Faculté des sciences > Département des sciences biologiques
Déposé par:	Christian Messier
Date de dépôt:	29 nov. 2011 14:18
Dernière modification:	01 nov. 2014 02:20
Adresse URL :	http://archipel.uqam.ca/id/eprint/4272

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