Factors limiting the early survivorship of Thuja plicata on northern

) Sarg.) – amabilis fir (Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes) (HA) stands. Shade, moss competition, and substrate were tested as causes of low cedar establishment. Cedar seeds were sown on reference and local soils isolated from surrounding soil, on nonisolated local soil, and on forest floor with moss removed. Western hemlock, amabilis fir, and cedar seeded on forest floor acted as controls. Treatments were implemented in the HA interior and the HA–clearcut edge, with soil treatments also imple-mented in clearcuts. Germinants and very young seedlings of cedar have a low leaf area of needle-like primary foliage. Cedar development of secondary foliage (the scale foliage normally associated with this species) was correlated with greater vigour and growth. Secondary foliage developed in the rankings forest edge and clearcut> forest interior, and reference isolated soil> local isolated soil> nonisolated local soil. Seedling survival rankings were edge> interior, and amabilis fir> hemlock> cedar on soil and with moss removed> cedar on forest floor. Cedar and amabilis fir showed a smaller growth response to light than hemlock. The results indicate that cedar, normally considered a late successional species, needs disturbance for early seedling establishment and survival and thus has some characteristics of an early seral species. Résumé: Les semis de thuya (Thuja plicata Donn ex D. Don), une espèce de fin de succession dans le Nord de l’île de Vancouver, ont un faible taux de survie dans les peuplements murs de pruche (Tsuga heterophylla (Raf.) Sarg.) e