Fringed sagebrush response to sward disturbances: seedling dynamics and plant growth.

Abstract

Fringed sagebrush (Artemisia frigida Willd.), the most common dicotyledonous species in the Northern Mixed Prairie, often increases dramatically following disturbance. It was hypothesized that the increase could be due to release of established plants, increased recruitment of plants, or both. Experiments were conducted on a sandy range site in central Saskatchewan. Tillage, clipping, litter removal, and a combination of clipping+litter removal were compared to an undisturbed control to determine their effects on emergence and survival of fringed sagebrush 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 moderate. Growth of plants was improved 2- to 3-fold by tillage the second year; this stimulation in growth was due to the removal of competition. Activities that reduce or remove vegetation and create bare soil surfaces promote emergence and growth of fringed sagebrush on the Northern Great Plains. Most seedlings of fringed sagebrush emerge in spring and early summer, enabling them to temporally exploit the period for optimal growth. Fringed sagebrush is well adapted to persist in Northern Mixed Prairie in a successional continuum from early to late seral stages.