Impacts of rodent eradication on seed predation and plant community biomass
Description
Island ecosystems have experienced massive biodiversity loss, and invasive species, in particular rodents, are responsible for much of this loss (~15%). Rodent eradications have led to the recovery of over 100 island vertebrates and their ecological roles. While the focus of most eradication efforts has been vertebrate recovery, rodents are generalists that predominantly eat seeds and fruit. However, there has been limited work on the effects of rodent eradication on plant communities and plant-mediated ecological processes. In this study, we conducted repeated surveys of seed, juvenile, and adult tree abundance and survival in permanent vegetation plots across an islet network (Palmyra Atoll) in the Central Tropical Pacific, before and after the eradication of black rats (Rattus rattus). Our aim was to examine the role of seed predation on tree communities and biomass. We observed an 84% decrease in seed predation of an introduced foundational species (the coconut palm, Cocos nucifera), and a 14-fold increase in juvenile tree biomass in all species following eradication. Juvenile C. nucifera abundance increased 2-5 times more than other tree species, leading to a 10% increase in population growth rate and a 4-fold increase in adult tree biomass accumulation over the next tree generation. We conclude that rodents can have nuanced impacts on island ecosystems, including facilitation of other invasive species and alteration of ecosystem functions such as carbon and nutrient cycling and storage. Future eradication efforts need to incorporate plant responses, since plants can shape post-eradication recovery trajectories. These data include census data from permanent vegetation plots on Palmyra Atoll, data used to determine community biomass from these plots, maps of Palmyra Atoll and the vegetation plot locations, and statistical tests used to determine changes in stages and vital rates for tree species in the permanent vegetation plots.