PARENT SESSION
Poster Session 20: Invasive Species
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Spread of an exotic tree, the glossy privet (Ligustrum lucidum), in central Argentina.
Gavier, Gregorio*,1, Hoyos, Laura *,2, Radeloff, Volker1, 1 University of Wisconsin, Madison2 Universidad Nacional de Córdoba, Cordoba, Argentina
ABSTRACT- The invasion of exotic species is one of the main factors of habitat loss and species extinctions. The glossy privet (Ligustrum lucidum) is an Asian tree that is becoming widespread in forests of central Argentina, where it forms dense stands. No studies have been conducted determining the extent of the invasion. The objective of this study was to assess the spread of glossy privet over the past 20 years. We used Landsat TM images to map glossy privet stands in 1983 and 1997, and field sampling to analyze the extent and floristic composition of selected stands, their dispersion over time and their spatial relationship with other landscape features. The study area (24,000 ha) is located in 31S-64W (Cordoba, Argentina). The area is largely forested but has witnessed increasing urban growth. The Landsat images were classified with a maximum likelihood classifier. Ground sampling was conducted in 52 plots 10 x 10 m located in glossy privet dominated stands and 14 in the surrounding native forest. In the plots, we sampled all trees (>2.5 cm dbh) and seedlings. Between 1983 and 1997 the area occupied by glossy privet increased from 200 to 1,115 ha. The number of these stands increased from 25 to 135, and the size of the largest stand from 23 to 125 ha. Most of the stands were in the vicinity of urban centers. The mean cover of glossy privet in invaded areas is 82,9 percent, with a density of adult trees of up to 3,000 stems/ha. The floristic composition and diversity is substantially different between the glossy privet stands and the surrounding native forest, with just a few native trees remaining in the invaded stands. Also, the glossy privet seedlings are dominant in the surrounding native forest plots. These results show a high degree of invasion of glossy privet, and the value of Landsat TM images to monitor the invasion of this species. Glossy privet should be considered a top priority in plans of exotic species control and monitoring in central Argentina.
Key words: ligustrum lucidum, invasive trees, central Argentina, Landsat TM