From relict saline wetlands to new ecosystems: changes in bird assemblages
Published: Volume 63.2, September 2016. Pages 329-348.
In the Pampa ecoregion of South America, the replacement of semi-natural ecosystems by agroecosystems is a major cause of biodiversity decline. Agricultural intensification has led to the almost total disappearance of pristine wetland vegetation and the decline of bird assemblages. Relicts of saline wetlands and modified surrounding habitats were chosen to explore differences and similarities in the assemblage structure of birds inhabiting the habitat spectrum from natural relicts to new agricultural ecosystems, in central Argentina. The study area is in the Pampa region, in the sector known as Flat Inland Pampa. Specifically, it is located in Marcos Juárez department, southeastern Córdoba province, Argentina. We identified eight habitats with contrasting floristic compositions and structures and three bird count surveys were conducted during an annual cycle: January-February, July-August, and October 2013. Fixed-radius survey stations were established in each habitat. Sixty bird species, from 21 families, were recorded. The results in terms of species diversity and trophic guilds indicate that bird species assemblages are associated differentially with different vegetation communities. The highest values of bird richness and guild numbers were recorded in structurally complex natural vegetation environments. The structurally simpler habitats modified by human activities were poorer in their bird assemblages. We conclude that the promotion and conservation of the patchiness of the landscape of natural saline wetlands (mixed grassland-shrubland) as the main physiognomies of the vegetation should have high priority in future agendas for conserving the integrity and diversity of bird populations of the remaining natural habitats in the Pampa ecoregion.