Galapagos Invasive Species:
Noxious weeds


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Roads and trails as invasion corridors for weeds

From a range of human activities carried out within the Galapagos National Park (GNP), roads and trails were found to be the most important, in a study carried out in the 1990s by Patricia Jaramillo of the Botany Department of the Charles Darwin Foundation. Recent projects have followed this up, studying the importance of disturbance as an environmental variable in promoting plant invasions. Two current projects managed by Scott Henderson and Heinke Jäger of the Foundation involve regular monitoring of plots in two areas across a range of habitat and disturbance conditions. These areas are the Garrapatero Road, built from the agricultural zone to the east coast of Santa Cruz island, to reach a recreational beach, and a trail built for cell-phone antenna construction and maintenance, which extends from the agricultural zone to Cerro Crocker, the highest point of Santa Cruz. The photo shows the monitoring work along the road. monitoring work

The monitoring projects register all native and introduced plants in permanent plots along both routes. Although native vegetation so far continues to dominate in both disturbed and undisturbed areas, the waysides contain considerably more introduced species than adjacent intact vegetation, and the number is steadily growing. Monitoring allows us to determine whether introduced species become more numerous over time and whether some areas are more susceptible to the establishment of introduced species. If the results show that some of these introduced species become “transformers”, altering the habitat character and structure in a major way, then plans can be made to control them. At this stage, species that have proven invasive in other parts of Galapagos, or in comparable habitats elsewhere in the world, should be eliminated before their invasive tendencies are unleashed by a change in environmental conditions.

Future trail and road building projects in the Galapagos National Park should pay for the expertise and activities required to provide the monitoring and analysis to ensure the GNP’s integrity. Long-term monitoring projects are costly, and control action to deal with invaders spreading along trails is even more expensive. The companies and institutions that derive benefit from such construction should bear the full cost of minimising their impact on the Galapagos National Park.

Source: Charles Darwin Foundation.


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This website was created on 25 October 2004 by PT and JK