Coarse woody debris decomposition documented over 65 years on southern Vancouver Island

Abstract

In 1929-1930, Stig Schenström and J.D. Curtis established an experiment to study thinning dynamics of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) on southern Vancouver Island, British Columbia. As a subcomponent of the experiment, the coarse woody debris (CWD) from the previous stand were mapped and the decay condition classified on five permanent plots. These scaled drawings and classifications were updated in 1945-1947 and 1995-1996. This unique 65-year period of CWD observation confirms that observations of CWD volume loss on Vancouver Island are similar to elsewhere in the Pacific Northwest. The simple exponential decay rate constant was 0.022 ·year -1 based on volume of primarily Douglas-fir on the five plots. The decay rate constant by large-end diameter was 0.067 ·year -1 for logs <= 20 cm, 0.056 ·year -1 for 21-40 cm, 0.021 ·year -1 for 41-80 cm, and 0.012 ·year -1 for logs > 80 cm.