Postfire succession in Pinus albicaulis – Abies lasiocarpa forests of southern British Columbia

Abstract

To examine postfire succession in forests where Pinus albicaulis Englem. is common, we conducted chronosequence studies in two areas of contrasting climate in southern British Columbia. Tree age and growth data indicated that Pinus albicaulis established rapidly following fire disturbance but that trees also continued to establish in late seral stands. Interactions with Pinus contorta Dougl. ex Loud., which grows faster, are pivotal in controlling the population dynamics of Pinus albicaulis. Where Pinus contorta established abundantly after fire, it dominated stands and limited the abundance of Pinus albicaulis, even after the postfire Pinus contorta had largely died. In contrast, where few or no Pinus contorta established, Pinus albicaulis dominated stands throughout most of the successional sequence. Although Pinus albicaulis decreases in abundance in late seral stands, we found no evidence that it would be completely replaced by more shade-tolerant species in our study areas. Thus, Pinus albicaulis is not only a pioneer species like Pinus contorta, even though it establishes in abundance after disturbance, but also a stress tolerator, with population dynamics molded by its ability to grow slowly and persist for long periods under adverse conditions and by bird dispersal of its seeds.Key words: Abies lasiocarpa, forest fire, Picea engelmannii, Pinus albicaulis, Pinus contorta, succession.