Human activities have resulted in the introduction of invasive plants species to Galapagos, some of which are negatively affecting native plant communities. These impacts are most visible on the inhabited islands of the archipelago. The best known examples are guava (Psidium guajava), Spanish cedar (Cedrela odorata), elephant grass (Pennisetum purpureum), quinine (Cinchona pubescens) and blackberry (Rubus niveus).
Blackberry is the worst plant invader in Galapagos - invading all vegetation types in the wetter parts of the islands and transforming native vegetation into dense thickets. This is particularly the case at Los Gemelos, Santa Cruz, where blackberry displaces the unique daisy-trees (Scalesia pedunculata), as well as other native plant species. The invasive quinine tree covers more than 12,000 hectares of land on Santa Cruz Island. Quinine negatively affects the abundance of endemic species, especially that of Miconia robinsoniana at Media Luna, and alters the micro-climate and phosphorus concentrations in the soil.
CDF scientists and collaborators are investigating plant invasions and helping the Galapagos National Park Directorate (GNPD) to improve control methods for blackberry and quinine. We are researching ways to minimize the impacts on non-target species, as well as evaluating the effectiveness of current control methods. In addition, we are collaborating with the GNPD in the restoration of areas affected by invasive plants, such as the Scalesia forest at Los Gemelos.
Collaborators: Galapagos National Park Directorate (GNPD), Galapagos Biosecurity Agency, Ministerio de Agricultura, Ganadería, Acuacultura y Pesca, Fondo para el Control de Especies Invasoras de Galápagos, Brown University, USA, CAB International, University of Tübingen, Germany.
Funders: Galapagos Conservancy, DFG (Deutsche Forschungsgemeinschaft) and Marie Curie International Outgoing Fellowship within the 7th European Community Framework Programme. The GNPD provide in-kind funding support through project staffing.
Links to publications
Jäger, H., Tye, A., and Kowarik, I. (2007) Tree invasion in naturally treeless environments: impacts of quinine (Cinchona pubescens) trees on native vegetation in Galápagos. Biological Conservation 140:297–307