Dr. Karen L. Johnson, (Retired) Curator of Botany

One of my major research projects looks at the long-term effects of fire on the boreal forest of eastern Manitoba, Canada. The study started in 1976 and more than 40 Museum staff and volunteers have assisted me with it along the way. We are documenting and trying to interpret the patterns of plant recovery and distribution on wet and dry sites in the area. Dr. W.O. Pruitt and the University of Manitoba’s Department of Zoology maintain a small and primitive field research facility, the Taiga Biological Station (TBS), off the northwest end of Wallace Lake. TBS is reached only by boat in summer and skis or snowmobile in winter. It is usually the base camp for several research projects. This is rugged Canadian Shield granite ridge, lake and bog country, with no near neighbours to help if you get lost or break a leg.

Fire is a normal part of the life cycle of the boreal forest. Many of its plants are ingeniously adapted to survive it and colonize bare ground. The changing pattern of plants seen after fire is part of an ecological process called ‘succession’. In its simplest form, it starts with bare ground and ends up with a prairie, pine forest or tropical rain forest. In the boreal forest of Manitoba, most end-stage communities are dominated by jack pine on the driest sites, white spruce/balsam fir on moist sites, and black spruce/larch on bogs.

To follow succession, I set up permanent study plots on wet and dry burned areas after each of the three fires. These have been re-marked and monitored almost every year. ‘Control’ plots were set up nearby to serve as models of what had been on the ridges and bogs before the fires. The 1980 fire burned most of the north side of Wallace Lake, including parts of the TBS and one of my control plots. The 1987 fire burned off most of the remaining mature forest on the south side of Wallace Lake and burned a small area which had been hit by both the 1976 and 1980 fires.

Each plot provides information on the changing amount of ground covered by different plants as well as bare ground, charcoal, water or logs. It gives the number and kind of shrubs and trees present in addition to the estimated amount of ground shaded at noon by shrubs and trees. Each plot is photographed every year to record the changes taking place.

Since 1976, burned wet areas have gone from bare charcoal through mosses to jack pine trees more than eight metres tall. Plots with more than 500 jack pine seedlings in 1977 now have eight to 10 tall crowded trees with almost nothing growing under them. Dry areas went from bare rock to small areas of lichens, mosses and grasses. Differences between areas burned once, twice or three times are obvious, as are those between similar areas burned in 1976 and 1980. I suspect the latter are the result of a fairly moist summer after the fire in 1976 and a series of drought summers after 1980. Many more jack pines and other trees survived, and lichens cover more rock area on the 1976 burn than on the 1980 one.

I hope to some day start the analysis and writing on this project and to eventually publish it as a Museum Occasional Paper or in a major journal. This is ‘bare bones’ ecological research but even these simple methods should, because of the length of the study, yield useful information on the successional patterns in this interesting and little-studied region.