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Leaf lifespans of five dominant shrub species, belonging to the Asteraceae (Compositae), were determined at a high elevation páramo site (4060 m a.s.l.) in Ecuador. Although climatic conditions in this cold, aseasonal environment appear to be quite constant year-round, leaf half-lifes of shrubs varied by nearly an order of magnitude (2.7 to 21.7 months). Foliar nitrogen concentration was negatively correlated with leaf lifespan, while leaf mass per unit area (LMA) increased with increasing lifespan. It appears that persistence in this high-elevation environment is not related to particular leaf traits or habit (e.g. long-lived, evergreen leaves). In fact, results of a mini review suggest that tropical, high elevation shrubs have leaf traits intermediate to those attributed to evergreen/deciduous leaf habits. Observed leaf traits also challenge recent models that assume that maximization of net carbon gain is the primary determinant of leaf longevity. Rather, the predominance of a particular leaf lifespan is the result of a number of physiological factors related to the leaf carbon balance, such as carbon gain, construction and maintenance costs and duration of the growing season, but also and perhaps more importantly, herbivory, architecture, soil nutrient status, evolutionary history and biogeography.
Matthias Diemer (Sun,) studied this question.