PARENT SESSION
Oral Contributed Papers: Case Studies
Moderator: Seastedt, Tim1, 1 University of Colorado, Boulder, CO
Wednesday, November 5, 2003, 10:00 AM to 12:00 PM
Key West
Detecting spatial and temporal changes of exotic woody species in El Palmar National Park, Argentina.
Sinton, Diana*,1, Scopel, Ana1, Minotti, Priscilla2, 1 University of Buenos Aires/CONICET, Buenos Aires, Argentina2 CAECE University, Buenos Aires, Argentina
ABSTRACT- We analyzed spatial and temporal changes in the woody coverage of El Palmar National Park, a temperate palm savanna ecosystem located along the eastern edge of the Province of Entre Rios, Argentina (approximately 31° 55′ S, 58° 16′W). The Park was created in 1965 with its primary objective to maintain and protect the largest remnant collection of a native species of palm tree, Butia yatay. Since its establishment, management activities (exclusion of grazing, fire suppression) and an increase in the animal population, both native and exotic (birds, foxes and wild boars), have facilitated and accelerated the invasion of several exotic species, including the trees Melia azedarach, Ligustrum lucidum, and Gleditsia triacanthos, and the shrub Pyracantha atalantoides. In its efforts to combat the spread of these invasives, particularly M. azedarach, the Park has chemically and manually treated over 55% of the vegetated landscape since 1981. We used geometrically and radiometrically corrected Landsat TM and ETM imagery from the years 1985, 1994, 2000 and 2001 to calculate overall changes in the growth of woody vegetation (using NDVI and MSAVI), and spectral, textural and other GIS-based analyses to generate the distributions of individual exotic species. Since 1985, the area covered by woody vegetation has undergone a 3-fold increase, currently covering almost 30% of the vegetated surface. This increase, primarily associated with the spread of woody exotic species, has not been spatially uniform or consistent in its expansion, both as a result of plant control activities and land use. Gallery forest, palm savanna and grasslands have been the environments most affected by these invasions.
Key words: El Palmar National Park, Argentina, Melia azedarach, remote sensing