Emergence and mortality of Douglas-fir, western hemlock, and western redcedar seedlings

Emergence of natural seedlings on the H. J. Andrews Experimental Forestin west-central Oregon between 1956 and 1967 was irregular from year to year; butmost seedlings appeared between April 15 and May 15. Average percentage of first-year mortality was: Douglas-fir 82, western hemlock 97, and western redcedar 95.Major causes of first-year mortality, in percent, were: Douglas-fir—animal 58,weather 27, and disease 6; hemlock—weather 58, disease 21, and animal 11; redcedar-weather 80, animal 8, and disease 2. Cumulative losses of Douglas-fir seedlings, inpercent, were: 1 year 83, 2 years 86, 3 years 86, 4 years 88, 5 years 88, and 6 years 89.Seedling protection might be most productive if directed toward animals for Douglas-fir and toward weather for hemlock and redcedar. Forest Sci. 17:230-237.
Additional key words. Pseudotsuga menziesii, Tsuga heterophylla, Thuja plicata, animaldamage, mortality, natural regeneration.