| Urbanization in Winnipeg has been associated with both a loss of forest cover and a change in the species composition of the remaining forest communities. This thesis is an attempt to discover the role seed dispersal plays in the decline and recovery of riparian forests.; The relatively limited dispersal evidenced from isolated forest fragments suggests that active planting of propagules may be necessary to maintain native species diversity as distance from extant forest increases. An introduction experiment was undertaken in an abandoned agricultural field and two neighbouring, historically grazed, forest patches. That the seed rain, seed bank, and aboveground vegetation at these sites were all depauperate and similar to one another indicates that, if left to natural processes, little vegetation change would occur in the future. The introduction of native species was hampered by the dominance of competitive exotic species. The introduction of shade and leaf litter mulch concurrently with planting suppressed exotic species and increased success of planted species. (Abstract shortened by UMI.)... |
