Format: ORAL

Svenja Wanke*, Mani Shrestha, Andreas von Heberg Anke Jentsch

University of Bayreuth, Germany * Presenting: svenja.wanke@uni-bayreuth.de

Flower colour plays an important role in structuring plant communities and is under selection by pollinators. Recently, the significant discrepancy between flower colour vision by humans versus pollinators has been discussed, which must be taken into account when considering the role of flower colour in communication with pollinators. Since bedrock and soil conditions are known to affect plant community composition, and can also affect flower colour directly, studies on flower colour composition of a community should include bedrock as an environmental variable. Elevational gradients in high mountain ranges are particularly suitable to study patterns and drivers of plant community diversity, including plant functional trait distribution relevant for trophic interactions. We measured flower colour spectra within six highly diverse grasslands on both calcareous and silicious bedrock across an elevational gradient in the European Alps: Hohe Leite (500 m asl), Brunnenkopfalm (1500 m), Obergurgl (2500 m), Kaserstattalm Stubai (1850 m), Arnspitze (1700 m) and Furkapass (2400 m). We collected flowers or petals of 315 locally occurring, insect-pollinated plants and measured their light reflectance property using ocean optics spectrophotometer. We used the bumblebee color vision model to translate spectral data into bee-colours because bumblebees are representative insect pollinators from low to high elevation in the European Alps. Our primary results suggest that for humans white and yellow flowers increase with higher elevation, whereas for bees blue and green flowers increase. Our data shows that calcareous grasslands have a higher color diversity than siliceous grasslands based on human vison, but higher number of blue and bluegreen flowers based on hymenopteran vision. Subalpine area shows a higher color diversity based on human vision, despite alpine regions harboring a higher number of plant species. Based on pollinator vision, more species with blue and bluegreen flowers occur in the alpine than in the subalpine region.