Dona, Amy J. , Galen, Candace .
On the edge: Survival in coloninzing populations of fireweed, Epilobium angustifolium.
Fireweed, Epilobium angustifolium, has recently established in the willow mosaic (Salix sp.) that characterizes the timberline ecotone in the Colorado Rocky Mountains. To investigate the influence of abiotic and biotic landscape structure on survival, seedlings and adults of fireweed were transplanted into experimental microsites varying in shade, wind exposure and proximity to willow over-story. Microsites varied dramatically in abiotic conditions. Average values for wind speed, soil relative water content and light intensity ranged from 0-2.47km/hr, .067-.343, 81-2172 µmol s-1 m-2 respectively. Wind break presence significantly decreased seedling survival in experimental plots while increased wind speed under the willow canopy promoted seedling survival. These trends likely reflect the role of wind in promoting rainfall penetration through artificial obstructions and through the willow canopy. Adult plant survival was enhanced by artificial shade and correlated with soil relative water content within the willow canopy. Seedling survival was positively correlated with adult survival in experimental plots, suggesting significant overlap in the regeneration niche and fundamental niche of fireweed. Results suggest that water relations have an important role in determining fireweed’s capacity to successfully colonize the alpine habitat. In this process, willows appear to have complex effects: acting as nurse plants by providing shade but as possible competitors in excluding rainfall to fireweed immigrants.
1 - University of Missouri-Columbia, Biological Sciences, 105 Tucker Hall, Columbia, Missouri, 65211, USA
Presentation Type: Poster
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM