Great Basin Naturalist


The effects of elevation and environmental parameters associated with elevation on the dinitrogen fixation rates, N2[C2H2], of a North American lupine species were evaluated. Lupinus argenteus Pursh plants growing at five elevations on Francis Peak, Utah, were sampled weekly throughout the growing season. The highest elevation site had the greatest frequency of nodulated plants. Influence of the environmental and physiological variables on fixation activity varied with elevation and the mean time of sampling. Soil moisture, nodule dry weight, and air temperature were important. Less than one-half of the observed variation in fixation rates, N2[C2H2], was accounted for by variation in the associated independent variables. Nevertheless this study documented that nodulated plants of L. argenteus were capable of actively fixing nitrogen at a range of elevations on Francis Peak.