Galapagos History, Restoration, and a Shifted Baseline

An ecological system that had been resilient to climatic change for thousands of years was transformed in decades by the introduction of livestock to the Galapagos. Habitat restoration at El Junco, San Cristobal Island, has included the exclusion of cattle, removal of exotic species, and replanting with the endemic shrub, Miconia robinsoniana. M. robinsoniana was known to form a characteristic zone of near mono-dominant shrub cover at equivalent elevations on other islands. Analysis of modern and fossil pollen data from El Junco Crater Lake showed that two of the most common shrubs of the San Cristobal uplands, Acalypha and Alternanthera, were the most common pollen types for more than two thousand years. In the 1930s, 30years before the first scientific description of that habitat, the abundance of both taxa declined rapidly as livestock densities increased. The restoration target, based on the assumption that mono-dominance by M. robinsoniana is the natural state, reflects a shifted baseline. Acalypha and Alternanthera should be considered for inclusion within future restoration efforts.