Tree demography and migration:What stand level measurements can tell about the response of forests to climate change

Abstract

Renewed interest in plant migration has developed due to the potential impacts of global climate change. Predictions from general circulation models and bog/lake pollen analyses suggest major shifts in species ranges, and even extinctions, over the next 50 to 200 yr in response to temperature shifts of up to 4.5°C (e.g., Davis & Zabinski 1992; Overpeck et al. 1991; Pastor & Post 1988; Peters 1990). Using computer simulation, Overpeck et al. (1991) predicted shifts in plant ranges of as much as 500 to 1000 km within periods as short as 200 yr. Others (e.g. Davis & Zabinski 1992) suggest the possibility of near extinction of species such as sugar maple Acer saccharum Marsh, and American beech Fagus grandifolia Ehrh. because establishment in newly suitable sites would fail to keep pace with a changing climate. In developing simulation models, relationships between species’ occurrence and climatic variables are developed or inferred using modern or historical data (Denton & Barnes 1987; Gajewski 1987; Prentice et al. 1991; Spear et al. 1994). Future ranges are then predicted assuming a strong relationship between species and climate, which can be compared to estimated migration rates by species as evidenced in the pollen record.