Document: LUC-3-39-13

Jack Pine (Pinus banksiana Lamb.) population dynamics at its eastern distribution limit in Quebec.

BABEAU, M.* and L.SIROIS

Université du Québec à Rimouski, Rimouski, Québec, Canada ¹

Abstract:
At their geographical distribution limits, tree species are subject to local extinctions and expansions caused by environmental and climatic alteration of either natural or anthropic origin. This study of 24 jack pine populations at their eastern distribution limit in North America allows us to better understand ecological and physiological phenomena responsible for these limits. Our objective is to characterize and compare the dynamics and growth patterns of jack pine populations in three habitats: Glacial deposit, rocky outcrops, and peat bogs. Moreover, we want to measure the impact of fire suppression since 1973 on these populations. Populations on rocky outcrops have continuous regeneration, even without fire, because of opening of cones due either to lower serotiny and/or environmental factors, such as high sun exposure. The population on glacial deposit show signs of senescence because of low fire frequency. In this habitat, jack pine demonstrates: Comparatively fast growth because of a thick deposit; halts in development when it reaches its physiological limit; and lack of regeneration. As a result, there is development of competing species and these populations become depauperate. In a context of lower fire frequency at the eastern distribution limit of jack pine, rocky outcrops, frequent in this region, could become refuges for this species if it disappears in the other habitats.

Keywords: Jack Pine, distribution limit, population dynamics, glacial deposit, rocky outcrops, peat bogs

This abstract is being presented at: 4:30 PM in session:
Oral Session #16: Plant Demography: Trees and Shrubs.