6 septembre - Conférence sur l'agroforesterie tempérée

Le ministère des Relations internationales et de la Francophonie du Québec, le Centre d’étude de la forêt, le Groupe interdisciplinaire de recherche en agroforesterie et la Chaire en développement international de l’Université Laval ont l’honneur d’accueillir deux sommités dans le domaine de l’agroforesterie pour une conférence portant sur les systèmes agroforestiers tempérés.

Shibu Jose
, professeur et directeur de l’école des ressources naturelles (School of Natural Resources) de l’Université du Missouri, et Rebecca L North, professeure associée à l’Université du Missouri, présenteront respectivement des communications sur les interactions écologiques au sein des systèmes agroforestiers des régions tempérées et sur les ressources hydriques dans un contexte de changements climatiques.

Ces conférences auront lieu le jeudi 6 septembre à 15h, à la salle 2320-2330 du pavillon Gene-H. Kruger de l’Université Laval.

Ecological interactions in polycultures: Lessons from temperate agroforestry

Shibu Jose
, Professor and Director, The School of Natural Resources, University of Missouri, Columbia, USA


The incorporation of multiple species in a single ecological system such as polycultures brings about a unique set of ecological interactions among the different species. If polycultures can be designed so that resource needs of individual species are spatially or temporally different, then there is a possibility that the system may accrue greater yield than the cumulative production of those species if they were grown separately on equal land area. Overtime, this advantage may disappear as competitive vectors overtake complementary interactions, but management intervention may bring the yield advantage back. An understanding of both the biophysical processes and the mechanisms involved in the allocation of resources is essential for the development of ecologically sound polyculture systems that are sustainable, economically viable, and socially acceptable. Results from temperate agroforestry trials during the past two decades have shown both competitive and facilitative (complementary) interactions in agroforestry systems, which occur both above-and below ground. For example, competition for light can decrease yield of C4 crops such as warm season grasses or corn in the understory, but cool season perennial grasses may benefit from partial shade. While competition for nutrients occurs in temperate agroforestry, nutrient capturing from deeper layers of soil by deep-rooted trees has beneficial effects in terms of efficient nutrient recycling and water quality. Hydraulic lift by tree roots can redistribute water to upper direr layers of the soil and help shallow-rooted species in mixed plantings. The complex biophysical interactions of multiple species in polycultures that determine the ecological sustainability are still not fully understood. Although scientific principles developed in temperate agroforestry may be applicable in some situations, site-specific research and demonstration are needed for the broad spectrum of environmental conditions and species combinations found across the temperate world.