Seasonal thaw and landscape position determine foliar functional traits and whole‐plant water use in tall shrubs on the low arctic tundra

Climate warming is driving tundra shrub expansion with implications for ecosystem function and regional climate. Understanding associations between ecophysiological function, distribution environment necessary predicting consequences of expansion. We evaluated the role topographic gradients on upland productivity to understand potential constraints At a low arctic site near Inuvik, Northwest Territories, Canada, we measured sap flow, stem water productivity-related functional traits in green alder, environmental predictors (water nutrient availability seasonal thaw depth) across toposequence alder patches. Seasonal reduced flow whereas position predicted traits. Upslope shrubs were more water-limited than those downslope. Shrubs drainage channels had associated greater tops slopes. The effect depth has water-use patterns impacts ecohydrology. Topographic variation corresponds observed spatial along floodplains concave hillslopes rather areas. Green expanding rapidly northwestern North America; thus, anticipating its essential function.