ROOT PROFILES OF SELECTED COLD DESERT SHRUBS AND GRASSES IN DISTURBED AND UNDISTURBED SOILS

The root depths and maximum lateral spreads of two shrubs and four perennial grass species were examined in disturbed (backfilled) and undisturbed soil using I-131 as a soil injected radiotracer. Although individual species differences were found, root distributions were not universally larger in one soil type or another. Big sagebrush (Artemisia tridentata ssp. wyomingensis) roots were detected deeper in the undisturbed soil (1.00 vs 0.75 m), while green rabbitbrush (Chrysothamnus viscidiflorus) roots were detected deeper in undisturbed soil (1.00 vs 0.50 m). Streambank wheatgrass (Elymus lanceolatus) and crested wheatgrass (Agropyron cristatum) roots were detected deeper in disturbed soil (1.00 m vs 0.75 m). Basin wildrye (Leymus cinereus) exhibited the greatest lateral root spread (0.90 m). Soil moisture, rather than soil disturbance, seemed to dictate root depth.