Conifer Encroachment on the Chilcotin Grasslands of British Columbia

Abstract

Detailed quantitative examination of a grassland/forest ecotone near Williams Lake, B.C. showed that a combination of fire, grass competition and subtle micro-site determinants of soil moisture availability appear to be the factors influencing tree encroachment most strongly. Historically fire has inhibited tree establishment on the grasslands — between 1759 and 1926 the fire interval approximated 10 years. Presumably because of heavy grazing, no severe fires have burned the area since 1926. Conifer encroachment began in 1931 and virtually ceased in 1972.