Climatic change in the Arctic typically leads to more productive and homogenized landscapes dominated by erect shrubs that inhibit spring snowmelt through shading. Increases in plant productivity are commonly observed in regions where shrubs, such as willow (Salix) and birch (Betula), are expanding in size and stature due to reduced physiological limitations. Larger shrubs trap in more snow, leading to an elevated level of warming in the Arctic permafrost, a known carbon sink for greenhouse gasses that are released upon thaw. It is hypothesized that a reduction in the metabolic constraints that limit growth height may lead to a similar increase in leaf size and other related traits. However, few studies show the physiological response of leaf area to warming over time using herbarium records. Here, we ask two questions: How has willow and birch leaf area changed in the Arctic with warming temperatures over the past 100 years? Is change in leaf area of these two groups related to the Arctic climatic subzones classification? As shrubs experience fewer limitations to their growth height and diameter during the growing season, we expect similar physiological changes to occur in their leaves. Leaf measurements will be taken from digitized herbarium vouchers spanning the last 100-200 years, and analyzed in relation to environmental variables. We expect leaf area to increase more in lower latitude subzones e.g., E > D > C for willows and E > D for birch. Leaf traits such as leaf area can show responses to increasing carbon dioxide concentrations, temperature, and precipitation with an increasing leaf area. As the Arctic experiences climate warming at a rate nearly four times faster than the tropics, the question is whether plant species can sustain their biological equilibrium to keep pace with such rapid environmental changes.