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Plant traits and nutrient limitation of Cecropia in abandoned pasture in Puerto Rico.
Gleeson, Scott1, Fetcher, Ned2,3, Zimmerman, Jess2, 1 2 3
ABSTRACT- Cecropia schreberiana is a dominant pioneer species in natural forest disturbances but fails to colonize abandoned pasture. It grows poorly when planted there but flourishes when fertilized, indicating a strong nutrient sensitivity. A variety of traits were measured in an attempt to determine which plant traits most likely contribute to this sensitivity, that is, to identify the limiting traits. To examine these traits we planted two size classes of seedlings of Cecropia into pasture, with and without competitors and/or fertilizer. For comparison, we also planted it in rejuvenated forest gaps and included a second species (Tabebuia heterophylla) that does colonize pasture. Traits measured included growth, architecture, leaf size, angle, tissue N, chlorophyll, longevity, SLA, photosynthetic performance, and variable fluorescence. Most traits showed considerable plasticity to changed conditions in adaptive directions. Leaf longevity, however, was short in Cecropia and unaffected by nutrient supply (although it did respond to light level), suggesting that this trait may be important in inducing nutrient stress in degraded pasture.
KEY WORDS: nutrient limitation, limiting traits, leaf turnover, tropical pasture restoration