Classification of montane grasslands in central Argentina

Abstract

Question: We address the following questions: (1) which are the main plant communities in montane grasslands in central Argentina; (2) do those communities differ in terms of floristic composition, endemisms, chorotypes and life forms; and (3) which are the major environmental variables (climatic, topographic and edaphic) associated with the heterogeneity of the vegetation? Location: Pampean Mountains (Sierras Pampeanas), Córdoba Province, central Argentina, an area of ca. 37,000 km2 . Methods: The survey was based on a data set comprising 746 relevés and 822 vascular plant species, collected in accordance with the Braun-Blanquet sampling method. The data were classified using the hierarchical ISOmetric feature mapping and Partitioning Around Medoids, and ordinated through isometric feature mapping (ISOPAM). The environmental variables were related to the ISOPAM ordination. Results: The ISOPAM classification identified two clusters, five vegetation types and 17 plant communities, which were distributed across different elevations. There were notable differences in the diagnostic species, average percentages of endemic species, chorotypes and life forms among the various vegetation types and plant communities. The primary gradient in grassland vegetation was found to be associated with elevation and related climatic variables. Conclusions: The study provides valuable insights into the montane grasslands of the Sierras Pampeanas in central Argentina. It presents a comprehensive classification of the region's grasslands, including tall tussock grasslands, humid grasslands, stony grasslands, and grasslands with scattered shrubs and trees. Each recognized unit is distinguished by diagnostic species and a distinct floristic composition. Our findings emphasize a significant division between grasslands at higher elevation, abundant in Andean species, and Piedmont and shrubby grasslands at lower elevations, characterized by a higher prevalence of Chacoan and other Neotropical species. Grassland vegetation in other regions of the Sierras Pampeanas remains poorly studied, requiring additional research to determine the syntaxonomic position of this vegetation.