Growth, maturation and survival of epiphytic bromeliads in a Mexican humid montane forest

摘要

Growth and survival of plants of eight species of epiphytic bromeliad were studied over a period of 5 y in a humid montane forest in eastern Mexico using repeated photographs of branches. Growth was calculated from annual size increment and used to predict the time taken to reach fertility. Most intermediate-sized plants grew at a rate of 2-3 cm y(-1), with the exception of Tillandsia deppeana, which does not invest in offshoots and grew about twice as fast. Tillandsia deppeana and two Catopsis spp. were predicted to become fertile after 11 and 9 respectively, T. multicaulis and T. punctulata after 13 y and T. juncea after 18 y. Individuals growing closer to the tree top tended to grow slightly faster. Relative growth rate calculated as biomass increase of the leading shoot was highest in T. deppeana and lowest in T. juncea. These differences are related to the proportion of biomass invested in offshoots, which are most numerous in T. juncea and mostly absent in T. deppeana. Fast maturation is particularly important for species growing on small and exposed branches, which experience higher mortalities caused by the breakage of their supporting branches.