Historical Ecology

For my Master’s research, with Dr. Mark Vellend in the Department of Botany at UBC, I studied the historical ecology of southeastern Vancouver Island and Saltspring Island, Canada. In particular, I was interested in how First Nations communities altered the landscape, and how those patterns changed when European settlers arrived.

Understanding the processes that shaped the presettlement landscape is especially important in this region due to the growing concern over the conservation of the endangered Garry Oak ecosystem.  The Garry Oak ecosystem is an open, savanna-like ecosystem with a diverse mixture of wildflowers and scattered Garry Oak trees. However, nearly 95% of the historical (presettlement) range of the Garry Oak ecosystem has disappeared due to development and forest infilling.

Garry oak meadow
Flowers of the Garry oak meadow ecosystem

I used historical land survey records from 1859-1876 to reconstruct presettlement tree species composition, size distributions, and density estimates, and compared these with present-day field observations.

A section of the map drawn from the 1859 survey of the Cowichan District on Vancouver Island

Anecdotal accounts suggest that frequent, small-scale fires – likely deliberately set by First Nations communities – may have been historically important in maintaining the Garry Oak ecosystem, with the subsequent European suppression of fire accounting for the infilling by Douglas-fir dominated forest.

Our research provided strong support for this hypothesis by showing that changes in tree species composition, tree density, tree size structure, and the relative abundances of different habitat types were all consistent with the hypothesis that fire was indeed an important process in the presettlement landscape. Current conservation and restoration efforts will need to account for this historically important process through active management.

For more information, see our paper:

Bjorkman, Anne D. and Mark Vellend. 2010. Defining historical baselines for conservation: ecological changes since European settlement on Vancouver Island, Canada. Conservation Biology, 24(6): 1559-1568. (link)(pdf)

And our related study:

Vellend, Mark, A.D. Bjorkman, and Alan McConchie. 2009. Environmentally biased fragmentation of oak savanna habitat on southeastern Vancouver Island, Canada. Biological Conservation 141(10): 2574-2584. (link)(pdf)