How much water is in the tank? An allometric analysis with 205 bromeliad species

Abstract

Tank bromeliads are prominent and distinctive components of many Neotropical forests. Functionally important for the plants themselves these phytotelms also represent important freshwater habitats in the forest canopy for a range of animal species and other biota. Existing literature values of the amount of water held in these tanks have never been systematically compiled nor has there ever been a systematic assessment of the water holding capacity of bromeliad tanks (tank capacity, TC) with a consistent methodology that covered a large taxonomic breadth of the bromeliad family.We determined TC for more than 200 taxa and collected additional data on total plant dry mass, projected area of the rosette (catchment area), and the number of individual reservoirs for a subset of them. These data were then used to establish intraspecific and interspecific allometric relationships of TC with plant size, the water held in living tissue, and the amount of rain necessary to fill the tank. This paper provides important baseline data for any study of tank function and gives a more modest picture of the “typical” bromeliad tank as often implied by the reference to extreme and unsubstantiated values in the literature.