During my field visits, I noticed that Redwood osier dogwood appeared more concentrated in the upland area that was further away from the human disturbance created by the intersecting walking path. In the southeast part of the upland, there were fewer shrubs under the canopy and more herbaceous species; however, in the northwest portion on the other side of the walking path, there was an increasing number of shrubs. One species that was more noticeably abundant in this region was the Redwood osier dogwood shrub. The dogwood species is the shrub that I chose to focus on for my research.
Observations during past sampling trips:
- The center contains moister soils due to the slight dip in elevation and the canopy cover of mature trees and increased understory.
- Edging effects are creating microclimatic conditions on the edge of the upland where there is less understory and the presence of a younger stand, resulting in drier conditions due to more radiation and wind exposure.
- The urbanization of the park and the trail system has intensified the habitat-edging effects.
- Dogwoods within the upland are relatively small and appear to be stunted (average shrub observed ~1.25m tall) to what literature suggests should be the mature size of the shrub. Possible factors causing the stunting could be the frequency of past flooding of the wetland and/or the browsing of ungulates on the shrub (browsing was detected on the dogwood plants, and flattened long grasses in the upland were an indicator of ungulates’ presence)
One of the ecological processes that might underlie my hypothesis below can be found in the literature reference below. The literature suggests that the edging influence created by anthropogenic disturbances on forest and wetland edges appears to extend a short depth into the habitat, and averages were consistently around 12 m or less (Harper et al., 2015). This finding is similar to my findings of the dogwood species at my sampling site, where the dogwood was almost absent in the first 10 m of the upland edge.
Keywords: anthropogenic, disturbance, ending effects
Hypothesis
Ha The distribution of the Redwood osier dogwood in the upland gradient at Lois Hole Park is controlled by habitat edging effects of urbanization.
Ho The distribution of the Redwood osier dogwood in the upland gradient at Lois Hole Park is not controlled by habitat edging effects of urbanization.
Supporting Literature
Harper, K. A., Macdonald, S. E., Mayerhofer, M. S., Biswas, S. R., Esseen, A., Hylander, K., Stewart, K. J., Mallik, A. U., Drapeau, P., Jonsson, G., Lesieur, D., Kouki, J., & Bergeron, Y. (2015). Edge influence on vegetation at natural and anthropogenic edges of boreal forests in Canada and Fennoscandia. Journal of Ecology, 103(3), 550-562. https://doi.org/10.1111/1365-2745.12398