Further study of conifer seed survival in a western Oregon clearcut

The survival of naturally disseminated, filled, seed of Douglas-fir (Pseudotsugamenziesii), western hemlock (Tsuga heterophylla), and western redcedar (Thuja plicata)was studied from 1960 to 1967. Ten per cent of the Douglas-fir seed survived from the startof seed fall until the end of germination the following year. Mice and shrews, mostly deermice (Peromyscus maniculatus), destroyed an estimated 41% of the seed; birds and chipmunks(mostly birds) took 24%; and other factors (nonviability of filled seeds, invertebrates, disease,and others) accounted for 25%. Western hemlock seed survival was 22%. Mice and shrews(mostly deer mice) destroyed an estimated 22% of the seed, birds and chipmunks (mostlybirds) 3%, and other agents 53%. The sample of western redcedar seed was too small tobe reliable. Douglas-fir seeds were preferred by ground-feeding birds and small mammals—less than half as many hemlock were taken. Most Douglas-fir and hemlock seed mortalityoccurred before the start of germination.