Assessment of Parque Luro Reserve effectiveness as a conservation tool for the Pampean Caldenal: landscape scale vegetation change between 1960 and 2004

Abstract

Protected areas are the main conservation tool being used to favor the preservation of natural ecosystems worldwide. However, it is notorious the scarcity of objective assessments on their effectiveness and long term conservation potential. The Caldenal is one of the most threatened ecosystems in Argentina, being in the margins of the Pampas agricultural region, conversion to croplands is its biggest conservation threat. Moreover, only 0.2% of the ecosystem’s area is formally protected in La Pampa province, being Parque Luro the only protected area in the region. Here we analyze, through the use of remote sensing techniques, Parque Luro Provincial Reserve’s performance as a conservation tool for the Caldenal ecosystem in La Pampa Province, Argentina. Abundance and spatial distribution of the different components of the land cover was analyzed at a landscape scale for the protected area, its immediate surroundings and in other reference areas in the rest of the Pampean Caldenal in the early 1960s (before the establishment of the protected area) and in 2004. High resolution panchromatic aerial photographs were used for 1960 and Landsat TM5 for 2004. Fragmentation indicators were also calculated for both periods. Results indicate that the establishment of the protected area has avoided the replacement of native forests by exotic annual crops, as is intensively occurring outside the limits of the park. However, even though Parque Luro maintains most of its area covered by woody plants, the structural characteristics of the current community greatly differ from those considered typical 100 years ago. The Caldenal was originally described as a savanna looking ecosystem, with scattered trees in a grassland matrix, while the community currently present in the reserve is that of a dense woodland. The process of landscape fragmentation has been intense in the three areas analyzed, regardless of the land use type. The mean and maximum patch sizes are still larger in the park as compared to the unprotected areas, but the proportional reduction in size was the same in all areas, suggesting a lack of effect of the establishment of the reserve in this regard. Finally, land conversion in the surroundings of the protected area has been very important in the 40 years analyzed, limiting Parque Luro’s connectivity to the unprotected remnants of the Caldenal ecosystem. Even though Parque Luro has been effective in maintaining woody cover within its boundaries, the process of woody plant encroachment, the high level of fragmentation in and outside the park, and its isolation from the unprotected natural areas greatly hinder its utility for the conservation of a functional and representative portion of the Pampean Caldenal ecosystem.