Garry oak (Quercus garryana)
Garry oak, which has its northern-most range limit in southwestern British Columbia, is confined to only a few isolated locations on Vancouver Island in Canada. Supported by a near-Mediterranean climate unique to this area, the Garry oak ecosystems currently comprise less than 0.3% of British Columbia’s entire land coverage. Supporting tremendous biodiversity, this area has simultaneously attracted rapid and extensive human settlement. Peripheral populations such as those found on Vancouver Island may play an increasingly important role as leading edge populations as climatically favourable habitat expands to the north of the current species range with climate change. In the absence of high levels of gene flow, marginal populations are often more locally adapted and are thought to harbour rare alleles necessary for adaptation.
In order to better understand the evolutionary forces acting upon Garry oak, and in particular, the relative role of divergent selection in creating the current genetic structure, quantitative genetic variation among and between populations has been assessed in a range wide study. Utilizing a common garden design, data regarding the quantitative traits of 1500 trees from 15 populations was collected over a two-year period and subsequently analyzed (Huebert 2009 (MSc thesis)). Garry oak has significant but relatively weak climatic clines compared to other widespread tree species. This suggests that restoration does not need to be highly restricted to local populations as sources of acorns. The results will help guide future conservation efforts in British Columbia and inform seed translocation guidelines for restoration.
Funding: Forest Investment Account through Forest Genetics Council of BC