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

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.