Fiona M. Soper Simon R. Poulson Paul C. Selmants Benjamin W. Sullivan Stephanie M. Freund 2018 <p><span>Actinorhizal plants&nbsp;form&nbsp;symbiotic&nbsp;root associations with dinitrogen (N</span>₂<span>) fixing&nbsp;</span><i>Frankia</i><span>&nbsp;and are abundant in North American cold deserts. However, the extent to which actinorhizal species are actively fixing N</span>₂<span>&nbsp;or altering ecosystem nitrogen (N) availability remains unclear. We used the&nbsp;</span>¹⁵<span>N natural abundance technique to measure how three widespread actinorhizal species in the western Great Basin of western North America acquired N and influenced soil N cycling and the N status of the surrounding non-fixing plant community. We compared foliar and soil N concentrations and&nbsp;</span><i>δ</i>¹⁵<span>N and soil&nbsp;biogeochemistry&nbsp;between reference plots and plots dominated by actinorhizal species. Actinorhizal species may be actively fixing N and influencing the N status of the surrounding ecosystem. Foliar&nbsp;</span><i>δ</i>¹⁵<span>N of actinorhizal shrubs was significantly depleted compared to non-actinorhizal species. Non-actinorhizal plants in the presence of actinorhizal species showed depleted foliar&nbsp;</span><i>δ</i>¹⁵<span>N and higher foliar N concentrations than in reference plots. Rates of N transformations in reference plots were similar to rates in actinorhizal plots; isotopic differences between plot types could not be explained by differences in N loss pathways. Actinorhizal species influence N cycling and availability in N-limited cold deserts, in a manner similar to&nbsp;leguminous plants&nbsp;in warm arid regions.</span></p> application/pdf 10.1016/j.jaridenv.2018.06.004 en Elsevier Actinorhizal species influence plant and soil nitrogen status of semiarid shrub-dominated ecosystems in the western Great Basin, USA article