| Summary: | Climate change is increasing air and soil temperatures in the Arctic, likely enhancing microbial activity. Consequently, increased decomposition rates of soil organic matter and increasing nutrient supply to tundra vegetation can be expected. The impacts of experimental warming and fertilization on growth have been investigated by studying the availability of macronutrients such as N, P and C. However, other macronutrients such as S, Ca, Mg, K, and micronutrients such as Fe, Mn, Cu, and Zn have received little research attention to determine their function, biogeochemical cycling, and effect on vegetation growth in response to warming. This study investigated the impact of experimental warming responses on availability and accumulation of the latter nutrients in the principal plant species located in mesic birch hummock tundra near Daring Lake, Northwest Territories in the Canadian Low Arctic Tundra. Plants were sampled in 2011 from the replicated summer greenhouse treatment that was established in 2004. In response to warming, the principal evergreen shrub (Rhododendron) had the most enhanced growth, followed by the deciduous shrub (Birch). Since the total plant pools of these nutrients were also enhanced in the evergreen, my results strongly suggest that availability of these nutrients was not limiting growth. By contrast, the birch total plant nutrient pools were not enhanced and significant decreases in Mg, S, and K leaf concentrations were observed, suggesting that these elements may be limiting birch growth. Together, our results suggest that plant growth response to climate change in the low Arctic may depend on previously overlooked nutrient elements, and that deciduous shrub growth may be constrained relative to the evergreen response as the arctic climate warms.
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