A GIS Assessment of Alpine Biodiversity at a Range of Scales

Abstract

Biodiversity is a complex concept that covers diversity in a continuum of organisational levels from genetic diversity within populations to functional diversity at a global scale. The scale problem is central, and organism groups reach their maximum diversity (taxonomic richness) per unit area at very different geographical scales. Cryptogams and soil invertebrates may have high genetic and taxonomic diversity at a patch size of <1 m2whereas other organism groups need to be assessed on a much larger spatial scale (grain size and extent, sensu Wiens 1989). Positive correlation between organism groups with regard to diversity (species richness) has rarely been investigated. The few existing data sets from alpine environments show a lack of correlation between the vascular plants of the herb layer and soil surface dwelling cryptogams at the 1 m2scale for species richness and diversity indices (Molau and Alatalo 1998). In addition to spatial aspects, longevity of individual organisms and dormancy (e.g. of seeds and meristems) highlight the importance of considering temporal scale in assessments of biodiversity. For many organism groups, such as birds and predatory mammals, diversity (taxonomic richness) assessments cannot be made at the grain size at which botanists usually work. Furthermore, at higher organisational levels of biodiversity (e.g. ecosystem diversity), meso-scale approaches are required. Most work in the twentieth century was made at two widely differing scales: small-scale (small grain size and small to large spatial extent) in most botanical studies and large-scale (large grain size and large spatial extent) ecosystem diversity assessments based on remote sensing.