FRINGED SAGEBRUSH RESPONSE TO SWARD DISTURBANCES - SEEDLING DYNAMICS AND PLANT-GROWTH

Fringed sagebrush (Artemisia frigida Willd,), the most common dicotyle donous species in the Northern Mixed Prairie, often increases dramatic ally following disturbance. It was hypothesized that the increase coul d be due to release of established plants, increased recruitment of pl ants, or both, Experiments were conducted on a sandy range site in cen tral Saskatchewan, Tillage, clipping, litter removal, and a combinatio n of clipping+litter removal were compared to an undisturbed control t o determine their effects on emergence and survival of fringed sagebru sh seedlings and growth of established plants, In no circumstance was seedling emergence or plant growth greater in the undisturbed control than in the disturbed sward. Emergence of fringed sagebrush seedlings increased almost 80-fold the second year after tillage at 1 site, but emergence was not altered relative to the control by clipping, litter removal, or clipping+litter removal, Averaged across treatments, 52 to 98% of the seedlings emerged in May and June, and 47 to 99% of these seedlings survived through the growing season and winter, Plants grew fastest in June when precipitation was highest and temperatures were m oderate. Growth of plants was improved 2- to 3-fold by tillage the sec ond year; this stimulation in growth was due to the removal of competi tion. Activities that reduce of remove vegetation and create bare soil surfaces promote emergence and growth of fringed sagebrush on the Nor thern Great Plains, Most seedlings of fringed sagebrush emerge in spri ng and early summer, enabling them to temporally exploit the period fo r optimal growth. Fringed sagebrush is well adapted to persist in Nort hern Mixed Prairie in a successional continuum from early to late sera l stages.