Post-Glacial Population Growth Rates of Pinus Contorta Ssp. Latifolia in Western Canada

Abstract

(1) Following the end of the last glacial stage, many plant species shifted their range limits to occupy favourable sites created by ice retreat and post-glacial environmental changes. The invasion of new sites consisted of range expansion and subsequent population growth. Little is known about geographic patterns in the rates of plant population growth as plant species invaded new regions. Information on geographic variation in population growth rates is important to understanding patterns and processes of plant invasion. (2) Pollen analysis is used to study the post-glacial rates of population growth of Pinus contorta ssp. latifolia at seven sites in western Canada. (3) The results suggest that pine invasion occurred by the establishment of small populations that then increased to present densities over periods ranging from 1000 to 4000 years. The rates of population growth were regionally variable and the degree of variability was extremely high. This variability may reflect climatic changes during periods of population growth and/or differences in regional edaphic conditions that affected regeneration.