Composition, structure and diversity of the arboreal vegetation of the Subtropical Mountain Forests or Yungas at the northern extreme of Argentina (Sierras de Tartagal, Alto Macueta and del Alto Rio Seco, Province of Salta)

Abstract

The Subtropical Mountain Forests or Yungas at the northern extreme of Argentina are studied with the aim of establishing the composition, structure and diversity of the arboreal vegetation. Fourteen relevés were made (0.1 ha each between 600-1160 m asl) where all the tree species and individuals were registered ≥ 5 cm of DBH. It was estimated the frequency, coverage and also the Importance Value Index (IVI) of the species and the families. It was determined the specific richness and diversity (Shannon-Wiener Index) of the study area, vegetation belts and relevés and the altitudinal distribution of the species. The studied forests show high richness (93 species, 77 genera and 37 families) and diversity (H´=3.8). The utmost ecological importance (IVI) corresponded to Anadenanthera colubrina var. cebil and Ocotea porphyria and to Fabaceae, Myrtaceae, Lauraceae, Boraginaceae, Bignonaceae and Sapindaceae. The Premontane Forest showed a singular floristic composition and major specific richness and diversity (69 species; H´=3.46) than the Montane Rainforest (61 species; H´=3.328) and the Riparian Forest (30 species; H´=2.821). A new register for Argentine flora is presented (Ficus cuatrecasasiana Dugand, Moraceae) and two new ones for Argentine Yungas (Diplokeleba floribunda N. E. Br., Sapindaceae and Cynophalla flexuosa (L.) J. Presl., Capparaceae).