Indicators for taxonomic and functional aspects of biodiversity in the vineyard agroecosystem of Southern Switzerland

Abstract

It is widely accepted that the concept of biodiversity embraces two essential and complementary components: taxonomic and functional diversity. Our goal is to produce a list of plant species predictive of high taxonomic and functional biodiversity values and discuss their use within biodiversity monitoring programmes. We selected a representative sample of 48 vineyard areas from Southern Switzerland, and vegetation from the ground cover was sampled from within a total of 120 sampling plots. We considered ten widely used functional traits and selected six taxonomic and functional indices. We applied a two-step analysis: (i) using Threshold Indicator Taxa Analysis (TITAN) based on the above mentioned biodiversity indices, we defined 3 groups of sampling plots with low (L), medium (M) and high (H) biodiversity values; (ii) using the Indicator Value analysis, we identify indicator species that are significantly associated with the above-mentioned groups and their combinations. In total, 259 vascular plants were identified across the sampling plots. As a whole, 52 species were significant indicators for groups with high and mid-to-high biodiversity values. Out of all indicator species, 24 (46%) were exclusively selected by functional biodiversity indices whereas only 10 (19%) were associated with taxonomic indices. Eighteen (35% of the total) species were selected by both types of indices. We point out that indicator species associated with two different aspects of biodiversity show a high degree of complementarity. Our results emphasize the need to consider functional aspects of biodiversity in diversity-conservation strategies when the objectives are to preserve both taxonomic diversity and ecosystem functioning.