Climate change has led to significant shifts in the flowering phenology of many plant species in temperate communities, but much less is known about phenological changes in tropical plants over the past 25 years. Since the 1980s, the flowering phenology of many hummingbird-pollinated plants has been studied in the Monteverde cloud forest reserve of Costa Rica. In order to determine whether flowering phenology of these plants has shifted over time, we compared current flowering patterns of 8 hummingbird-pollinated plant species to the flowering patterns of the same species in the 1980’s.
Initial measurements of flowering phenology were based on censuses of the number of open flowers along a transect at monthly or half-monthly intervals between 1981 and 1991. More recent measurements were made between January 2017 and February 2018.
Results/Conclusions
Our results provide evidence that epiphytic plants may be more sensitive to changes in climate than terrestrial plants. For the 2017-2018 sample period, half of the epiphytes sampled in the study both initiated flowering later and ended flowering earlier than in the 1981-1991 period. In contrast, terrestrial plants- though widely varied in their phenology from year to year- did not change their average flowering patterns. We suggest that the flowering phenology of hummingbird-pollinated plants in the cloud forest is sensitive to climate variations from year to year, but that epiphytic plants are more likely to shift their patterns over the long term than terrestrial plants. These changes in nectar availability could ultimately have important ecological effects on hummingbird populations. These changes in nectar availability could have important implications for hummingbird populations in addition to populations of other nectarivores.