Arthropod communities along an elevation gradient in Denali National Park and Preserve, Alaska: Rapidly shrinking tundra hosts a unique assemblage of specialists

Abstract

Arthropods at high latitudes and elevations are likely to be vulnerable to effects from climate change such as increased temperatures and shifting vegetation boundaries. Though range shifts northwards and upslope have been reported for many arthropod taxa in temperate latitudes, baseline data needed to track such changes are scarce at northern latitudes. We investigated the influence of climate and vegetation cover on the abundance, diversity, and species composition of pollinators and epigeic arthropods along an elevation gradient in Denali National Park and Preserve, Alaska. We compared arthropods across three habitat types: low-elevation forest, mid-elevation shrubs, and high-elevation tundra along five replicate transects over three years. We collected 35,473 arthropods representing 510 species. Arthropod communities differed distinctly across the three habitat types, with tundra having the highest number of strong indicators and unique species. Elevation, air temperature, and vegetation structure were strong drivers for the ordination of sites. As treeline and shrubline shift upslope with climate change, we predict that distributions of some arthropods will shift to track these habitat boundaries and that tundra-associated arthropods will be most vulnerable as their habitat shrinks. Long-term monitoring of arthropods along elevation gradients at northern latitudes is needed to detect such declines.

Keywords

• Pollinators
• insects
• elevation
• tundra
• climate change