INFLUENCE OF THE EXOTIC INVASIVE CRUCIFER, LEPIDIUM LATIFOLIUM, ON SOIL PROPERTIES AND ELEMENTAL CYCLING

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Abstract
Plant species and plant communities can alter element cycling promoting divergent pathways of soil development. We hypothesized that the exotic invasive crucifer, Lepidium latifolium, altered biogeochemical cycling relative to pre-existing vegetation such that sodium-affected subsoils are ameliorated. We tested this hypothesis at the Fleming unit within the Honey Lake Wildlife Refuge in northeastern California by comparing the distribution and cycling of various elements in paired L. latifolium invaded and noninvaded sites occupied by Elytrigia elongata. Soils are fine, smectitic, calcareous, mesic Fluvaquentic Endoaquolls. In 1998, per unit area, live biomass of L. latifolium was more than 3 times greater than that of E. elongata. Content of C, Ca, Mg, K, and S in aboveground tissue of L. latifolium was significantly (P ≤ 0.05) greater than content in E. elongata. Biogeochemical fluxes of C, N, P, Ca, Mg, and S were from 3 to 11 times greater in L. latifolium-occupied areas than in E. elongata-occupied areas. L. latifolium invasion fostered elevated soil solution levels of Mg+2 and Ca+2, thereby reducing sodium adsorption ratios that could lead to sodic soil amelioration. Invasion by L. latifolium has the potential to alter soil properties and processes, thereby altering the trajectory of soil evolution.