Chronological dating of high-elevation dead and dying trees on northern Vancouver Island, British Columbia

Tree rings were analysed in order to determine the time of death for 18 moribund and dead trees of 3 species used as roosts by bats on the upper slopes (700-1500 m altitude) of Mt. Cain, northern Vancouver Island, Canada. The species were yellow cedar (Chamaecyparis nootkatensis), western hemlock (Tsuga heterophylla) and western white pine (Pinus monticola). Some 29 increment core samples were crossdated with tree-ring chronologies of living trees to estimate when the trees died. After they die, yellow cedar trees deteriorate slowly and remain standing for as long as 200 years. In contrast, few western hemlock and western white pine snags persist longer than 100 years. The ages at which the sampled trees died were highly variable, with western white pine, western hemlock, and yellow cedar exhibiting the narrowest to widest range of ages, respectively. The findings highlight the long persistence of snags in high-altitude coastal forests and the centuries of ecological service that these trees provide to snag-dependent wildlife.Kellner et al "Chronological dating of high-elevation dead and dying trees on northern Vancouver Island, British Columbia." Northwest Science. 2000; 74(3): 242-24