Historical vegetation change in the Kananaskis Valley, Canadian Rockies

Abstract

This study compares the vegetation composition in the Kananaskis Valley from a forest survey in 1883 to another survey in 1972 and reconstructs the fire frequency for the period 1783 – 1882 and the period 1883 – 1972. A comparison of the 1883 to 1972 forest surveys using transition probabilities revealed that sites populated mostly by lodgepole pine (Pinus contorta) or Englemann spruce (Picea Englemannii) tended to remain the same in both surveys. The fire reconstructions for the period 1730 – 1972 showed no change in fire frequency after the beginning of European activity in 1883. Further, for the periods both before and after 1883, the valley burned, on average, once every 150 years. The distribution of the fire sizes for the 100-year period before 1883 was slightly larger than the period after 1883. It appears that in 1972 natural processes (site differences and fire occurrence) still dominated the changes in the vegetation composition and age.