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Relationships Among Leaf Construction Cost, Leaf Longevity, and Light Environment in Rain-Forest Plants of the Genus Piper

Among seven Piper species characteristic of multiple stages of rain-forest secondary succession, leaf construction cost increased and leaf longevity decreased as available light increased. Our results extend the observations of several recent studies reporting a striking constancy of leaf construction costs among co-occurring plants that differ in growth form or phenology. When Piper species characteristic of different habitats co-occurred, their leaf construction costs were similar. However, mean leaf construction costs for sun and shade species, based on plants sampled from the entire range of light environments, were quite different. We reject the hypothesis that leaf construction cost and leaf longevity are generally positively related. The arguments previously used to support the hypothesis lack generality because they fail to consider carbon income as well as cost. The data presented here are consistent with the results of several other recent studies in failing to support the hypothesis. We conclude that the more general hypothesis, predicting a positive relationship between longevity and the ratio of cost to carbon gain, is conceptually more robust and consistent with the data we present. This more general hypothesis derives logically from the arguments previously used to predict a positive relationship between longevity and cost.