Canadian Forest Service Publications
Competition theory – science and application in mixed forest stands: review of experimental and modelling methods and suggestions for future research. 2013. Larocque, G.R.; Luckai, N.; Adhikary, S.N.; Groot, A.; Bell F.W.; Sharma, M. Environ. Rev. 21:71-84.
Available from: Laurentian Forestry Centre
Catalog ID: 34756
CFS Availability: PDF (request by e-mail)
Competition in forest stands has long been of interest to researchers. However, much of the knowledge originates from empirical studies that examined the effects of competition. For instance, many studies were focused on the effects of the presence of herbaceous species on the development of tree seedlings or the decrease in individual tree growth with increases in stand density. Several models that incorporate competitive effects have been developed to predict tree and stand growth, but with simplified representations of competitive interactions. While these studies provided guidance useful for forest management, they contributed only partially to furthering our understanding of competitive mechanisms. Also, most competition studies were conducted in single-species stands. As competitive interactions occurring in mixed stands are characterized by a higher degree of complexity than those in single-species stands, a better understanding of these mechanisms can contribute to developing optimal management scenarios. The dynamics of forest stands with at least two species may be affected not only by competition, but also by facilitation or complementarity mechanisms. Thus, knowledge of the mechanisms may provide insight into the relative importance of intra- versus inter-specific competition and whether competition is symmetric or asymmetric. Special attention to the implementation of field experimental designs is warranted for mixed stands. While traditional spacing trials are appropriate for single-species stands, the examination of competitive interactions in mixed stands requires more complex experimental designs to examine the relative importance of species combinations. Forest productivity models allow resource managers to test different management scenarios, but again most of these models were developed for single-species stands. As competitive interactions are more complex in mixed stands, models developed to predict their dynamics will need to include more mechanistic representations of competition.
Plain Language Summary
In forest stands, competition affects tree growth. This positive or negative influence has most often been studied in stands composed of a single species, particularly in plantations.
However, the majority of Canada's forests are composed of more than one tree species, with up to a dozen species in some forest types, and many forests are composed of trees of different ages. Therefore, in order to study competition between the different species of trees and between trees of the same species, it is necessary to develop new methods of establishing appropriate experimental sites.
The knowledge gained regarding competition in mixed stands will then be integrated into existing models in order to predict tree growth and stand productivity. Improved understanding of the dynamics of mixed stands will help preserve the integrity of these ecosystems.
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