Abstract
The Arctic is warming twice as fast as the rest of the globe. Graminoid, deciduous shrub, and evergreen shrub cover has increased in some regions, but not others. To better understand why plant responses vary across regions, we compared change in plant cover over time with nine functional traits of 12 dominant species in three regions of northern Alaska (Utqiaġvik, Atqasuk, and Toolik Lake). Cover was measured three times from 2008 to 2018. Repeated-measures analysis of variance (ANOVA) found that one species — Carex aquatilis — showed significant change in cover over time, increasing by 12.7% at Atqasuk. Canonical correspondence analysis suggested a relationship between shifts in species cover and traits, but Pearson and Spearman rank correlations did not find a significant trend for any trait when analyzed individually. Investigation of community-weighted means (CWMs) for each trait revealed no significant changes over time for any trait in any region. By comparison, estimated ecosystem values for several traits important to ecosystem functioning showed consistent increases over time in two regions (Utqiaġvik and Atqasuk). Our results indicate that vascular plant community composition and function have remained consistent over time; however, documented increases in total plant cover have important implications for ecosystem functioning.
Highlights
The Arctic is susceptible to habitat degradation and loss caused by global climate change (IPCC 2018)
When analyzed by growth form, we found additional significant results: graminoids increased at Utqiaġvik (P
Change in Cover Our study regions span a latitudinal gradient that is coupled with a temperature gradient: the northernmost region had the lowest mean summer temperature and the southernmost region had the warmest mean summer temperature
Summary
The Arctic is susceptible to habitat degradation and loss caused by global climate change (IPCC 2018). Changes in community composition with warming have been documented across the Arctic, with increases in evergreen shrubs, deciduous shrubs, and graminoids and decreases in bryophytes and lichens being the most consistent trends across regions (Callaghan et al 2011; Elmendorf et al 2012; Hollister et al 2015; Bjorkman et al 2020). As a persistently cold and severely nutrient limited system, the Arctic consists of plants characterized by slow growth rates and low reproductive outputs; studies have shown that rates for both growth and reproductive effort increase with climate warming (Hollister et al 2005; Oberbauer et al 2013; Mekonnen et al 2018). The link between performance and ecosystem function has led to an increase in studies focusing on plant functional traits as a mean to study vegetation responses to changing environmental conditions (Chapin et al 1996; Messier et al 2010; Hudson et al 2011; Bjorkman et al 2018a; Myers-Smith et al 2019)
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