Phenological trajectories of Caribbean very dry tropical forests diverge under different geologic formations

Tropical dry forests experience pronounced seasonal changes in precipitation manifested in varied plant phenologies. At landscape scales, geologic substrate-one of the least understood abiotic factors interacting with precipitation-may modulate phenological responses in these forests through a combination of mechanisms regulating water and nutrient use. We leveraged a phenological dataset from the semiarid island of Curacao to examine the extent to which plant phenology at multiple levels of biological organization diverge under different geologies. Monthly observations over a 30-month period of leaves, flowers, and fruits of 69 plant species of different life forms at three nearby sites differing in their underlaying geology were used to examine intra- and inter-annual plant responses at species, community, and system levels. The integration of leaf, flower, and fruit observations at intra-annual scales revealed diverse phenological strategies among species, broad associations with geologic substrate, and the extent of intra-specific variation as a function of geology. The community- and system-level analyses at inter-annual scales showed a reduction in mean leaf scores during the 30-month period, a weak and strong leafless period in 1993 and 1994, respectively, and differences among geologic substrates. Finally, we observed significant and positive relationships between precipitation and the phenophase scores; the strength of the relationships varied with phenophase and geologic substrate. Results of this work emphasize the importance of geologic substrate, and more broadly speaking landscape heterogeneity, in modulating plant phenological responses in tropical dry forests. Ultimately, this information will become important to understand and mitigate global climate change impacts. Abstract in Spanish is available with online material.