PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Assessing climate-related vegetation change through aerial photography – a study of the southern boreal forest.

Swarbrick, Vanessa^{*,1, 2}, Vetter, Mary ¹, ¹ Luther College, University of Regina, Regina, Saskatchewan, Canada² Spencer Environmental Management Services Ltd., Edmonton, Alberta, Canada

ABSTRACT- Major changes to both the northern and southern boundaries of the boreal forest due to climate change are predicted to occur over the next 50 – 100 years. These events include invasion of temperate woodland from the south, alteration in species composition, and a northward migration of current boreal species. To assess the merit of these predications a better understanding of how climate variation influences forest composition is needed. The objective of this study was to assess whether the composition of the southern boreal forest had changed over a 50 year period, if the magnitude of change followed a latitudinal gradient, and whether those changes were related to changes in climate. I compared aerial photographs of the southern boreal forest from the late 1940s and 1990s. 20 - 500m x 500m plots from the southern boreal forest were analyzed. The sites were then grouped into three zones to determine if differences in the magnitude of vegetation change had occurred along a latitudinal gradient. Changes in climate parameters between the 1940s and 1990s were assessed using data from long-term monitoring stations located near the plots. Principal Component Analysis indicated that vegetation change had occurred throughout the study area; however changes in the size of all stand types in the study area were not statistically significant. Regression analysis of climate parameters for the total study area also indicated that no significant changes had occurred. Principal Component Analysis indicated that differences in the magnitude of vegetation change existed along the latitudinal gradient, with southern sites showing a smaller degree of vegetation change than the northern sites. However, Kruskall-Wallis ANOVA indicated that there was no significant difference in community vegetation change between the individual zones. When smaller geographical scales (within a zone) were analyzed, paired t-tests showed that the size of individual stands, including hardwood, softwood-dominated mixedwood, black spruce and bog did significantly change. Those changes coincided with significant (p<0.05) changes in certain climate parameters within the respective zones. Together, these analyses indicate that variations in microclimate might have larger influences on forest composition than larger scale changes in climate.

Key words: boreal forest, vegetation change, climate, aerial photography