High nitrate variability on an Alaskan permafrost hillslope dominated by alder shrubs

Abstract. In Arctic ecosystems, increasing temperatures are driving the expansion of nitrogen (N) fixing shrubs across tundra landscapes. The implications this to biogeochemistry ecosystems critical importance and more work is needed better understand form, availability, transportation potential N from these a variety To gain insights into processes controlling within permafrost hillslope system, spatiotemporal variability nitrate (NO3-) its environmental controls were investigated at an alder (Alnus viridis spp. fruticosa) dominated landscape in Seward Peninsula, Alaska, USA. Soil pore water was collected locations shrubland growing along well-drained compared soil outside (upslope, downslope, between) shrubland. had average NO3-N (nitrogen nitrate) concentration 4.27±8.02 mg L−1 differed significantly (0.23±0.83 L−1; p<0.05). Temporal variation downslope co-occurred with precipitation events where NO3- that accumulated likely flushed during rainfall. These findings have important for nutrient availability mobility N-limited systems experiencing shrub response warming Arctic.