Water residence times in trees of a neotropical dry forest

Key message Water residence times in trees of a Neotropical dry forest increase with tree diameter and decrease with wood density during the rainy season. Abstract In tropical dry forests, tree species with different drought coping strategies co-exist; leaf deciduous and stem-succulent trees are prominent among them. The actual role of stem succulence in tree water use is not fully understood. In a premontane dry forest of southern Ecuador, five tree species were studied in the rainy season including one stem-succulent species ( Ceiba trichistandra ). All species were studied at the same site and some also across a soil moisture gradient. Deuterium tracing suggests species-specific mean residence times between 11 and 22 days. Mean residence times for Ceiba and two other deciduous tree species were about twice as high as those of two evergreen tree species. Differences in soil moisture did not significantly affect tree water residence times. Our and literature data indicate that across species, residence times increase with tree diameter and decrease with wood density. The stem-succulent Ceiba is characterized by a big stem and a low wood density; the observed residence times in the rainy season were situated on the continuum as derived from a larger data set. The succulent stem may, however, play a special role for leaf flushing at the end of the dry season.