XVI International Botanical Congess

Cecropia schreberiana is a dominant pioneer species in natural forest regeneration but is a suprisingly minor component of abandoned pasture succession. Why? Previous studies show high seed predation and low seed germinationfor Cecropia in pasture. We planted seedlings of Cecropia into pasture to study growth and ecophysiology in two size classes of seedling,with and without competitors and/or fertilizer. For comparison,we also planted it in rejuvenated forest gaps and included a second species (Tabebuia heterophylla) which does colonize pasture.In pasture, Cecropia growth and photosynthetic capacity were comparatively poor. Dramatic response to fertilizer implicated nutrients as the main stress inhibiting Cecropia growth in pasture. The physiological basis for this sensitivity to nutrient stress is unknown.