Hurricane disturbance may affect foliar tannin concentrations of buttonwoods on Bahamian islands

Hurricanes are important drivers of intense, episodic, and spatially variable disturbances on small island communities in the Bahamas. This island system provides a particular opportunity to begin investigating the long-standing hypothesis that disturbance regimes predictably influence foliar quality via an ecosystem-level feedback loop. We studied a set of 21 small islands and one mainland to investigate how variation in the prevailing disturbance regimes of island communities influences tannin concentrations in a common plant species. We observed high variability in the foliar tannin concentrations of buttonwoods (Conocarpus erectus), with significantly lower tannin concentrations observed on more disturbed islands. This pattern was consistent across two distant island groups, with one notable exception. This outlier was the only island in our sample whose plant community included a nitrogen-fixing, rhizobia-symbiotic legume, Pithecellobium keyense; buttonwoods on this island showed markedly lower tannin concentrations than predicted by the overall trend. Taken together, these observations support the hypothesis that tannin production is positively correlated with expected leaf longevity, and intense disturbance regimes favor rapid plant regrowth at the expense of foliar tannin allocation. The singular co-occurrence of low tannin concentrations and nitrogen-fixing legumes provides an alternative avenue of indirect support for the hypothesis that rapid plant growth is negatively correlated with foliar tannin concentrations. The function of these foliar tannins remains uncertain, but these current findings are consistent with previous observations of rapid regrowth, decreased trichome densities, and increased rates of herbivory following hurricane disturbances.