Latitudinal Gradients in Arctic Willows and Their Effects on Stream-Riparian Systems

Extreme warming in the Arctic due to climate change presents the opportunity to study rapid changes to ecosystems and their potential resilience. Willow (Salix) shrubs form the base of many Arctic riparian ecosystems, and they have increased in height and range as temperatures have warmed. The effects of warming on willows could alter riparian ecosystems and neighboring streams, so understanding how climate change will affect willows is integral to understanding how the stream-riparian meta-ecosystem might change. I used data from the EvoME Institute to compare willow canopy cover above Arctic streams along a latitudinal transect and investigate how changes in above-stream canopy cover and stream characteristics affect benthic primary production. Above-stream canopy cover increased at higher latitudes, but relationships between benthic chlorophyll a and canopy cover, latitude, or stream characteristics were not significant. These results suggest that increasing temperatures may decrease willow canopy cover above streams despite increased willow heights. Changes in willow height and shading above streams will likely have bottom-up effects on riparian and stream ecosystems, as well as altering the trophic subsidies between the two, although further study is needed to understand the effects of changing canopy cover on stream primary production.