COARSE WOODY DEBRIS DECOMPOSITION DOCUMENTED OVER 65 YEARS ON SOUTHERN VANCOUVER-ISLAND

In 1929-1930, Stig Schenstrom and J.D. Curtis established an experimen t to study thinning dynamics of Douglas-fir (Pseudotsuga menziesii (Mi rb.) France) on southern Vancouver Island, British Columbia. As a subc omponent of the experiment, the coarse woody debris (CWD) from the pre vious stand were mapped and the decay condition classified on five per manent plots. These scaled drawings and classifications were updated i n 1945-1947 and 1995-1996. This unique 65-year period of CWD observati on confirms that observations of CWD volume loss on Vancouver Island a re similar to elsewhere in the Pacific Northwest. The simple exponenti al 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 d iameter was 0.067.year(-1) for logs less than or equal to 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.