Fire history and grassland vegetation change: three pollen diagrams from southern British Columbia

Abstract

Recent vegetation change in the grasslands of southern British Columbia is examined using pollen analysis, and the results are compared with documentary records. The increasing dominance of the grasslands after 1890 by Artemisia tridentata and other woody shrubs has often been attributed to overgrazing by domestic livestock, but pollen data indicate that shrub populations were substantial in presettlement times, and that the recent "invasion" represents a recovery from anomalously low population levels during the middle 19th century. These low Artemisia populations were probably due to a high frequency of fire in the early settlement period, and the subsequent recovery is probably related to fire suppression. Fire appears to have been an important element in the ecology of these grasslands over a long period, and it may have a place in modern management schemes.