Format: ORAL

Christian Krner1, Erika Hiltbrunner1, Christian Newesely2, Ulrike Tappeiner2

1 University of Basel, Basel, Switzerland 2 University of Innsbruck, Innsbruck, Austria

Naturally treeless by definition, the vegetation covered terrain of the alpine belt amounts to c. 2 % of all land outside Antarctica. Despite the assumed hostility for life, it embraces an estimated 4 % of all flowering plant species. Habitat diversity created by topography and a microclimate that deviates strongly from what meteorological stations report, are the explanation for this unexpected biodiversity. The habitat diversity across short distances offers unique opportunities to study the long-term effect of contrasting environmental conditions on biodiversity and ecosystem functioning. We present concepts, definitions, challenges and pitfalls in monitoring terrestrial ecosystems and the study of steep gradients of life conditions related to snow duration and length of growing season, with a focus on snowbed and adjacent grassland communities. We provide a synthesis of findings obtained during seven consecutive seasons of monitoring with a standardized protocol, across four monitoring sites in the Swiss and Austrian Alps. We show that plant dry matter allocation is highly conserved across such gradients, while the ratio of graminoid to herb biomass emerges a sensitive indicator for season length. Microclimate and phenology data will be presented that illustrate the key role of timing for alpine plant life, and underpin the central role of the aerodynamic boundary layer near the ground and exposure for alpine plants. Data from such late successional ecosystems will facilitate projections of the consequences of future changes in season length and they complement findings from early successional systems such as those studied in the GLORIA network. For further reading see: Krner C (2021) Alpine Plant Life, Springer; Körner and Hiltbrunner (2021) Diversity 13:383; Körner et al. (2022) EcoMont 14:48-69.