Evaluating the plant composition and abundance of Santa Fé, Galápagos, 50 years after the eradication of feral goats

Abstract

Invasive species detrimentally impact island ecosystems, particularly native species that evolved in their absence. From the early 1800’s to 1971, feral goats heavily grazed on the native vegetation of Santa Fé Island, Galápagos. Feral goats were eradicated from Santa Fé in 1971, allowing native plant populations to begin to recover. However, the long term effects of feral goat eradication from this island are not well understood, which is particularly important in the context of the recovery of slow-growing arboreal plants like Opuntia echios and Bursera graveolens. This project assessed the recovery of woody plant species on Santa Fé 50 years after the eradication of feral goats, an building on vegetation monitoring previously done from 1971 to 2003. Since the last assessments in 2003, the slower-growing woody species such as Opuntia echios and Bursera graveolens did not increase notably in density over time, but their population demographies shifted to a higher concentration of younger individuals. There was also a marked increase in the density of fast-growing woody species such as Cordia lutea, Encelia hispida, and Lantana peduncularis. Overall, results for both slow- and fast-growing plants demonstrate that this system is still recovering from feral goat removal some 50 years later. This vegetation assessment provides increased clarity on how plant populations in island ecosystems recover over long time periods after the eradication of an invasive ungulate.