Light Response of Seedlings of a Central African Timber Tree Species,Lophira alata (Ochnaceae), and the Definition of Light Requirements |
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Authors: | Achille Bernard Biwolé Kasso Dainou Adeline Fayolle Olivier J. Hardy Yves Brostaux Sabrina Coste Sebastien Delion Jean Lagarde Betti Jean‐Louis Doucet |
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Affiliation: | 1. Département Ingénierie des biosystèmes, Université de Liège, Gembloux Agro‐Bio Tech, Axe Gestion des ressources forestières, Gembloux, Belgium;2. Ecole Normale Supérieure d'Enseignement Technique, Université de Douala, Douala, Cameroon;3. Ecole Régionale Postuniversitaire d'Aménagement et de Gestion Intégrés des Forêts et Territoires Tropicaux, Kinshasa, République Démocratique du Congo;4. Laboratory of Applied Ecology, University of Abomey‐Calavi, Cotonou, Benin;5. Service d'Evolution Biologique et Ecologie, Université Libre de Bruxelles, Bruxelles, Belgium;6. Gembloux Agro‐Bio Tech, Unité de Statistique, Informatique et Mathématique appliquées, Université de Liège, Gembloux, Belgium;7. UMR Ecologie des Forêts de Guyane, Université de Guyane, Kourou Cedex, France;8. Wijma Cameroun SA, Douala, Cameroon;9. Faculté des Science, Département de Biologie des Organismes Végétaux, Université de Douala, Douala, Cameroon |
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Abstract: | Light is of primary importance in structuring tropical tree communities. Light exposure at seedling and adult stages has been used to characterize the ecological profile of tropical trees, with many implications in forest management and restoration ecology. Most shade‐tolerance classification systems have been proposed based on empirical observations in a specific area and thus result in contradictions among categories assigned to a given species. In this study, we aimed to quantify the light requirements for seedling growth of a Central African timber tree, Lophira alata (Ochnaceae), taking into account effects of population origin. In two controlled experiments: a light response experiment and a comparative population experiment, conducted in southwestern Cameroon, using seeds collected from four populations (three from Cameroon and one from Gabon), we examined the quantitative responses to irradiance of seedlings. After 2 years, mortality was very low (<3%), even in extremely low irradiance. Growth and biomass allocation patterns varied in response to light, with intermediate irradiance (24–43%) providing optimal conditions. Light response differed between populations. The Boumba population in the northeastern edge of the species' distribution exhibited the highest light requirements, suggesting a local adaptation. As a result of positive growth at low irradiance and maximum growth at intermediate irradiance, we concluded that L. alata exhibits characteristics of both non‐pioneer and pioneer species. Implications of our results to propose an objective way to assign the light requirement for tropical tree species are discussed. |
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Keywords: | biomass allocation Central Africa light requirement: Lophira alata population relative growth rate seedling growth timber species Afrique centrale allocation de biomasse besoins en lumiè re croissance des semis bois d'œ uvre
Lophira alata
population taux de croissance relatif |
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