Leaf lifespans of high-elevation, aseasonal Andean shrub species in relation to leaf traits and leaf habit

Leaf lifespans of five dominant shrub species. belonging to the Asteraceae (Compositae), were determined at a high elevation paramo site (4060 m a.s.l .) in Ecuador. Although climatic conditions in this cold, a seasonal enviro nment appear to be quite constant year-round, leaf hall-lifes of shrubs var ied by nearly an order of magnitude (2.7 to 21.7 months). Foliar nitrogen c oncentration was negatively correlated with leaf lifespan. while leaf mass per unit area (LMA) increased with increasing lifespan. It appears that per sistence in this high-elevation environment is not related to particular le af traits or habit (e.g. long-lived, evergreen leaves). In Fact, results of a mini review suggest that tropical. high elevation shrubs have leaf trait s intermediate to there attributed to evergreen/deciduous leaf habits. Obse rved leaf traits also challenge recent models that assume that maximization of net carbon gain is the primary determinant of leaf longevity. Rather, t he predominance of a particular leaf lifespan is the result of a number of physiological factors related to the leaf carbon balance, such as carbon ga in, construction and maintenance costs and duration of the growing season, but also and perhaps more importantly, herbivory, architecture, soil nutrie nt status, evolutionary history and biogeography.