AbstractGalapagos is an oceanic archipelago that has World Heritage status for its high degree of endemism and relatively pristine habitats. Unfortunately the terrestrial environment is experiencing habitat loss and species extinctions as a result of alien plant invasions. Impacts are concentrated on the four inhabited islands, where humans have introduced plants to rural areas in the humid highlands and urban areas on the arid coast. This study assesses the current status of alien plant invasion in Galapagos in relation to species properties, habitat invasibility, propagule pressure and residence time. Existing datasets are used to explore the spatial distribution of the alien flora among the inhabited islands. Results show that there are 919 recorded alien plant taxa in Galapagos, of which 16% have already become invasive and many more have the potential to invade or naturalize. The majority of introduced species have very small distributions. Half of the exotic species are ornamentals and it is suggested they are relatively recent arrivals. Galapagos is not yet as invaded as other oceanic islands in the world, probably because of the shorter residence time of the alien flora. This is predicted to change for the worse as the human population in the archipelago continues to increase.
Therefore this study concludes that Galapagos is at an early stage of invasion and hence will experience more invasions from the existing introduced flora. Results of the study highlight distribution patterns that can help prioritize the prevention of species transfers among islands, guide the detection and removal of higher risk species with limited distributions, and focus community awareness efforts to reduce spread and propagule pressure. Following these recommendations should reduce the risk of invasion into the National Park by the existing alien flora from the adjoining inhabited areas of Galapagos.
|Date of Award||2008|
|Supervisor||Penny Wurm (Supervisor), Diane Pearson (Supervisor) & Rachel Atkinson (Supervisor)|