South American terrestrial biomes as geocomplexes: a geobotanical landscape approach

Abstract

The classic and current perception of biome in its various meanings is fundamentally based on vegetation types that are considered as discrete or independent and fragmented entities in the landscape. Vegetation units are characterized by their physiognomy, which is based on the dominant life forms and mainly determined by climatic conditions. However, vegetation units are associated and mutually interacting at a landscape level. They are determined by local or regional, climatic, topographic and edaphic gradients within a given territory or geographic area. In this work, we propose a new conceptual and methodological approach aiming to better understand the biome concept in a landscape framework, developing ideas already partially advanced by us. In this sense, we consider the biome as a landscape complex (geocomplex), that spatially includes one to several vegetation geoseries which, in turn, each comprise the following possible geomorphologically linked vegetation series: i) the potential natural climatophilic vegetation (zonal vegetation) and their seral successional stages which occur repeatedly in the landscape; ii) edapho-xerophyllous vegetation (azonal vegetation such as occurs on rocky outcrops or sandy soils); and iii) edapho-hygrophilic vegetation (azonal vegetation such as flooded vegetation on river banks). Based on surveys and field data (more than ca. 300 transects) obtained by the authors in most South American countries from 1990 to the present, 33 South American geocomplex biomes and 16 macrobiomes were identified and synoptically characterized, through graphic general zonation models (phyto-topographic type-profiles) extrapolated from numerous observations along representative bioclimatical, geomorphological and biogeographically stratified transects. Field data and transect-plots are currently being processed to be included into the “GIVD database”. Taxonomic reference : Tropicos.org, Missouri Botanical Garden (https://tropicos.org) [accessed 1 Feb 2023]. In Memoriam : Salvador Rivas-Martínez