PARENT SESSION
Contributed Oral Session 47: Invasive Species: Environmental and Habitat Factors
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 520 A, Level 5, Palais des congrès de Montréal
Environmental factors determining the invasions of four naturalized Crotalaria species (Fabaceae) in Taiwan.
Wu, Shan-Huah1, 2, Sheu, Jia-En1, Lee, Pei-Fen1, Hsieh, Chang-Fu1, Rejmanek, Marcel2, 1 Institute of Ecology and Evolutionary Biology, National Taiwan University, Taipei, Taiwan2 Section of Evolution and Ecology, University of Califronia at Davis, Davis, CA, USA
ABSTRACT- We analyzed the distributions of four naturalized Crotalaria species (i.e., Crotalaria zanzibarica, C. pallida, C. micans, and C. incana) in Taiwan to test the hypothesis that environmental factors would determine the intensity of invasions in the field. The four Crotalaria species, which have been shown to possess different levels of invasiveness, were introduced from different tropical regions of the world and have been naturalized in Taiwan for more than 70 years. Herbarium records were examined and field investigations were conducted in 200 randomly-selected plots in the summer of 2002. Species, longitudes, and latitudes were recorded and mapped in a GIS. Approximately 30 environmental factors, e.g., eco-region, precipitation, temperature, urbanization, human population, etc., were used to examine critical limitation factors of these species at two spatial scales. Results showed that at the regional level, these Crotalaria species were harbored by different eco-regions in Taiwan: island-wide distributed C. zanzibarica possessed most field localities in the north, while C. pallida tended to expand in the south. C. micans and C. incana were categorized as locally distributed only in certain areas in the central region and the very south of Taiwan, respectively. At the plot level, the results showed local variations and supported our hypothesis that environmental factors, such as precipitation, variation in precipitation, water deficiency, temperature, variation in temperature, degree of urbanization, human population, and elevation, were important in determining the invasions of these species. Furthermore, potential distribution predicted by the herbarium records coincided with the field data, indicating that multiple scale approaches can be applied to studies and predictions on the invasions of potential invaders.
Key words: Distribution, GIS, Invasive species, Naturalized species