Christie Lake Fire Barrens
|A brief introduction to fire barrens of Lanark County
The fire barrens of LanarkCounty are not well-documented in easily available sources. Since even locally important examples such as the Christie Lake fire barrens are given insufficient attention, I am providing this short treatment of the topic for field naturalists, students and local citizens.
On the west side of Lanark County there are extensive areas of fire barrens. These barrens typically have Precambrian rock ridges covered with a thin layer of stony glacial till. They extend westward past the Kaladar area, eventually all the way to the edge of Georgian Bay. These areas are called barrens because they do not have a dense forest cover. In small areas of deeper soil, forest may form, but elsewhere there are only scattered trees. Typical trees of barrens include red and bur oak, large-toothed aspen, and red or jack pine. The plants are arranged in distinctive patterns along soil depth gradients. The bare rock may have only a few lichens. In slightly deeper areas of soil there may be larger lichens such as reindeer lichens, along with typical rock barren grasses such as poverty grass (Danthonia spicata). In deeper soil there will be more kinds of herbaceous plants including goldenrods, asters, milkweed and sunflowers, along with shrubs such as blueberries. Often these grow in crevices or depressions in solid rocks. During dry summers, one can readily see plants wilting or dying back in the drier areas.
The absence of forest is largely explained by the shallow soil. The other key factor is fire. Lightning-caused fires were likely common in these barrens, and they may have burned large areas, with only rivers or wetlands to stop their spread. Fire has been rigorously suppressed during the last century, which is no doubt causing changes in the plant communities, but overall there is still a good deal of evidence of fire, from burned stumps to fire dependent species such as blueberries and jack pine. The jack pine is well known as a species that can reproduce only after fires have opened its resinous cones. Oaks also re-sprout rapidly after fire. Apart from the distinctive trees, barrens have many other interesting plant species. The adjoining table shows just how many kinds of plant species occur here. One locally rare plant species, northern downy violet (Viola sagittata) occurs near Christie Lake. Wild orchids such as slender ladies'-tresses (Spiranthes lacera) also can be found in drier meadows. The prairie warbler is a bird species typical of barrens across Ontario. In Lanark County, the black rat snake and the five-lined skink are two distinctive reptiles in barrens. (The black rat snake is now, we are told, to be called the central rat snake, as a result of research by molecular biologists, but that is a different story). Blanding's turtles and spotted turtles can sometimes be found in the small ponds that extend through valleys in the barrens.
Finally, along with shallow soil and fire, beavers play an important role in controlling water levels in the valleys. They also change the forest composition by selectively cutting oaks and poplars and leaving the conifers.
Six hundred hectares of the Christie Lake barrens west of Perth have been given status as a provincial Area of Natural and Scientific Interest. More areas of interest and importance are likely to be found as biologists explore. As but one example, a new species of tree for Canada, bear oak (Quercus ilicifolia), was discovered only a few years ago in fire barrens to the west of Lanark County.
To learn more:
The key article on the ecology of local fire barrens is by Paul Catling and Vivian Brownell (1999), a chapter (pages 392-405) in the book Anderson, R.C., J.S. Fralish and J.M. Baskin. 1999. Savannas, Barrens, and Rock Outcrop Plant Communities of North America. Cambridge University Press, Cambridge, UK. Their chapter includes a list of typical species and a list of significant species.
Another good source of information is David White's Lanark County flora, now updated to 2008, which is posted on line at http://www.lanarkflora.com/plantlist.html. This list includes more than 1,000 plant species with documented occurrence in Lanark County.
For more general background on geology, a map of significant areas, and a discussion of how beavers affect local plant communities, you can see my book (updated to 2008), Earth, Water, Fire: An Ecological Profile of Lanark County.
For the story about the discovery of bear oak, you will have to ask your local librarian to find you a copy of this article: Brownell, V.R., C.S. Blaney and P.M. Catling. 1996. Recent discoveries of southern vascular plants at their northern limits in the granite barrens area of Lennox and Addington County, Ontario. Canadian Field-Naturalist 110: 255-259.