Flowering cues in a Costa Rican cloud forest: analyzing the effect of climate

ABSTRACT The influence of a changing climate on the phenology of organisms in a region is dependent on how regional climate cues or modifies the timing of local life history events and how those cues are changing over time. There is extensive evidence of phenolological shifts in flowering time over the past 50 years in response to increasing temperatures in temperate regions, but far less is known about tropical regions where seasonality is less temperature driven. We examined historical datasets of flowering patterns in two guilds of ornithophilous plants in the montane cloud forests of Monteverde, Costa Rica in order to identify environmental cues for flowering in nine species of plant that are important resources for hummingbirds. Bimonthly censuses of flower production were used to quantify flower production during two sampling periods:1981-1983, 1986-1991., the species studied here appear to cue flowering patterns to either accumulated drought units or a combination of accumulated drought units and chill units prior to flowering. These results have implications for how tropical cloud forest plants will respond to climate change to the extent that drought and chill patterns are changing with time.