Successive Thinnings in a Natural Stand of Douglas-fir (EP 62-66 and 283)


This experiment was the first of its kind to be established in BC. The experiment, sometimes called the Schenstrom Thinning Plots, was established in 1929 in a naturally regenerated stand of Douglas fir at age 18 years near Lake Cowichan, at what was to become the Cowichan Lake Research Station. The experimental project number has multiple numbers because, at the time, individual plots were numbered. Please review a brief history of the establishment of the Cowichan Lake Research Station.


  1. To develop a yield table based on a series of successive remeasurements
  2. To compare the yield of several plots thinned by different methods


Two methods of thinning and two intensities of each method were allocated to one plot each, and each compared to a single control plot.  Althought the original design called for crown- and low-thinnings, there was no consistent application of treatments; in general, competitors to the potential final crop trees were removed, regardless of dominance as in the classic interpretation of crown- or low-thinning.  The first thinnings took place in 1929 but poor markets almost prevented thinning in 1935 and 1940, resuling in the removal of dead and dying trees only at that time. Since establishment, there have been 8 thinnings 




  • Warrack, G.C. 1979. Successive thinnings in a natural stand of Douglas-fir over a fifty year period. B.C. Min. For., Victoria, B.C. Res. Note 87. 
  • Stone, J.N., A. MacKinnon, J.V. Parminter, and K.P. Lertzman. 1998. Coarse woody debris decomposition documented over 65 years on southern Vancouver Island. Can. J. For. Res. 28:788–793.