the alpine cushion plant silene acaulis as foundation species a bug’s-eye view to facilitation and microclimate高山垫状植物硅宾acaulis作为基础物种一个bug的便利化和小气候.pdf

The Alpine Cushion Plant Silene acaulis as Foundation Species: A Bug’s-Eye View to Facilitation and Microclimate 1 2 2 Olivia Molenda , Anya Reid , Christopher J. Lortie * 1 Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, 2 Department of Biology, York University, Toronto, Ontario, Canada Abstract Alpine ecosystems are important globally with high levels of endemic and rare species. Given that they will be highly impacted by climate change, understanding biotic factors that maintain diversity is critical. Silene acaulis is a common alpine nurse plant shown to positively influence the diversity and abundance of organisms–predominantly other plant species. The hypothesis that cushion or nurse plants in general are important to multiple trophic levels has been proposed but rarely tested. Alpine arthropod diversity is also largely understudied worldwide, and the plant-arthropod interactions reported are mostly negative, that is, herbivory. Plant and arthropod diversity and abundance were sampled on S. acaulis and at paired adjacent microsites with other non-cushion forming vegetation present on Whistler Mountain, B.C., Canada to examine the relative trophic effects of cushion plants. Plant species richness and abundance but not Simpson’s diversity index was higher on cushion microsites relative to other vegetation. Arthropod richness, abundance, and diversity were all higher on cushion microsites relative to other vegetated sites. On a microclimatic scale, S. acaulis ameliorated stressful conditions for plants and invertebrates living inside it, but the highest levels of arthropod diversity were observed on cushions with tall plant growth. Hence, alpine cushion plants can be foundation species not only for other plant species but other trophi