Yamagishi, Hiroki , Tomimatsu, Hiroshi , Ohara, Masashi .
Edge effects on demography of a perennial understory herb, Trillium camschatcense, within small forest fragments.
As habitats become fragmented and shrink in size, the relative proportion of the habitat that occurs on the boundary, or edge, increase. Edge effects can significantly degrade a populationís chances of survival. Changes in microclimate (temperature, wind, humidity, etc.) near edge may reduce appropriate habitat for many species more than the physical fragmentation suggests. However, it is difficult to detect edge effects on long-lived perennial plant populations. Since if we want to reveal the effects on population demography, we need long-term census for each individuals. Trillium camschatcense a long-lived perennial herb commonly occurs in the understory of broadleaved deciduous forests of Hokkaido, Japan. This species has been experienced dramatic changes in population size and spatial distribution by forest fragmentation due to. Our previous studies have suggested that alternation in population sizes by forest fragmentation may have significantly reduced seed production and genetic diversity. In this study, we analyzed how edge effect affects demography of T. camschatcense. We established a total of 43 (1m√ó1m) study plot at the forest edge and the interior in two fragmented populations. Every single individual within the study plots was monitored annually for four years. We analyzed these census data by matrix demographic modeling and compared those between the forest edge and the interior. Our results indicated that per-capita fertility (the number of recruits per plant) and population growth rates (λ) tended to be smaller in the edge than the interior. Life table response experiment analyses showed that the difference in fertility had not always largest effect on λ. The pattern of contribution to differences between the edge and the interior in λ was varied by the population and the years. This study revealed that edge effect reflected on difference in demography of T.camschatcense between the edge and the interior.
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1 - Hokkaido University, Faculty of Environmental Earth Science, Lab of Ecological Genetics, Sapporo, 060-0810, Japan
2 - University of British Columbia, Department of Botany, Vancouver, BC, Canada
Population growth rates
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM