The Descendants of Giants: In Search of Exemplary Specimens of At Risk Trees in Southern Ontario's Oak Ridges Moraine

Prior to widespread settlement by Europeans in the early to mid 19th century, southern Ontario (i.e., the region south of Lake Simcoe) was blanketed by dense mixed deciduous forests that had been shaping, and were being shaped by, the landscape for over 10,000 years. Today, over 95% of these once expansive forests have been cleared for agriculture and other forms of development (see Figures 1 and 2) (Berger, 2008; McLachlan and Bazely, 2003). This extensive clearance and land use alteration has imperiled the continued existence of many of southern Ontario's native tree species. \n \nCompounding this predicament has been a long history of over-harvesting the fittest trees in the forest, as well as the more recent introduction and spread of alien and native invasive species and diseases. There are no longer any old growth forests of significance left in southern Ontario. Over 95% of remnant Carolinian forest patches are less than 10 hectares in area and most are over 1.5 km apart (McLachlan and Bazely, 2003). The largest remaining stand of Carolinian forest in Canada is in Rondeau Provincial Park and is a mere 11 km2 (Tanentzap et al., 2011). Most remaining patches of Carolinian are tiny, scattered, and situated on marginal lands with poor soils that are ill-suited to agriculture (and thus ill-suited to supporting vibrant, diverse forests). As most of the healthiest and genetically superior specimens of rare southern Ontario trees were harvested for wood in centuries past, the genetic stock that remains in the region's patchwork of forests tends to be anything but robust (Schaberg et al., 2008). \n \nNot only are southern Ontario's Carolinian forests the most biologically diverse forests in all of Canada, but they are also the most threatened (Tanentzap et al., 2011). The Carolinian biome supports over half of Canada's total biodiversity, and over half of its tree species (roughly 100 tree species of the 180 in the country) (Feagan, 2013; Tree Canada, 2013). It is home to roughly 165 species officially recognized as vulnerable, of special concern, threatened, or endangered, 12 of which are trees (OMNR, 2011). In addition to these recognized species, there are also over 500 species considered to be rare in Canada's Carolinian forest region (CCC, n.d.). The Carolinian occupies roughly 0.25% of Canada's land area yet is home to over 25% of the country's population (McLachlan and Bazely, 2003; Tanentzap et al., 2011). The fact that such a densely populated and developed area also hosts such a rich array of native biodiversity poses many unique and formidable conservation challenges. \n \nThe purpose of this research was to survey a series of five protected areas in the western Oak Ridges Moraine region of southern Ontario, locate exemplary specimens of rare native trees, catalogue their exact location, write about my experiences, and make all of the information and resources I gather available to the general public.

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