Impacts of climate variability and human colonization on the vegetation of the Galápagos Islands

A 2690-year fossil pollen record from the Galápagos Islands reveals that vegetation changes were primarily driven by shifts in species abundance rather than immigration or extinction, with droughts during the Medieval Climate Anomaly inducing rapid but reversible ecological shifts. Human colonization significantly altered the ecosystem, leading to the decline of native species like Alternanthera and Acalypha before 1930 and their potential local extinction due to intensified animal husbandry. Post-1970 reductions in grazing animals did not restore the native flora but instead facilitated exotic species invasions, accelerating habitat change beyond historical variability. The study also suggests increased lowland pollen transport to uplands, consistent with warmer wet seasons and intensified convection.

Restrepo, A., Colinvaux, P., Bush, M., Correa-Metrio, A., Conroy, J., Gardener, M. R., Jaramillo, P., Steinitz-Kannan, M., & Overpeck, J. (2012). Impacts of climate variability and human colonization on the vegetation of the Galápagos Islands. Ecology, 93(8), 1853–1866. Portico. https://doi.org/10.1890/11-1545.1