Short-term effect of Hurricane Irma and Maria in the population of Gesneria pauciflora (Gesneriaceae)

The Caribbean was recently struck by two hurricanes (Irma and María) considered among the most powerful since 1928 in that region. !ese hurricanes brought intense and continuous rainfall, which likely impacted plants inhabiting riparian areas through flash floods and landslides. We conducted a post-hurricane assessment of Gesneria pauciflora, an endemic riparian species of conservation concern in Puerto Rico, to determine the number of individuals of this species, their distribution and their response to the infuence of these natural phenomena across its distribution range; also, the assessment was an opportunity to survey additional sites within and outside of the Maricao Forest Reserve. A total of 79 colonies were surveyed during the study period (56 known colonies and 23 new records), yet seven of the known colonies were extirpated due to landslide or flood-driven habitat modifications. The survey yielded 7,853 plants distributed across three sub-watersheds with non-reproductive plants comprising 65.2% of the plants surveyed, followed by reproductive adults (25.3%) and seedlings (9.5%). Plants were found in a variety of habitats associated with riparian environments. Results from colonies that had pre-hurricane information suggest that plant mortality could have been as high as 89% with variation likely resulting from differences in their location within the riverine system (higher mortality for colonies in the main channel of the watershed). There was approximately an 11% reduction in estimated canopy cover at the site, and percent plant mortality showed a negative association with canopy cover after the hurricanes. While the number of individuals is higher than expected for a threatened species, the patchy distribution of its populations justifies the continuation of monitoring activities for the species at larger spatiotemporal scales to examine potential delayed responses to these hurricanes.