Effects of Initial Site Treatments on Early Growth and Three‐Year Survival of Idaho Fescue

Abstract

Prairies in the Pacific Northwest have been actively restored for over a decade. Competition from non‐native woody and herbaceous species has been presumed to be a major cause for the failure of restoration projects. In this research, plugs of the native prairie bunchgrass, Festuca idahoensis Elmer var. roemeri (Pavlick), were grown from seed in a nursery and transplanted into a grassland site dominated by non‐native pasture grasses. The growth of the plants was followed for three years, and biomass of all volunteer plants was measured. Before planting, five treatments were applied to the plots: removal of vegetation by burning, removal of vegetation by an herbicide‐and‐till procedure, soil impoverishment by removal of organic matter, fertilizer application, and compost mulch application. Initial growth of Idaho fescue plugs was greatest with fertilizer and compost mulch. Plants grown in mulched plots were also able to photosynthesize later into the dry summer season. After the first year, plots initially fertilized or composted had the lowest survival rate of Idaho fescue. Impoverished and herbicide‐and‐till plots had the greatest 3‐year survival. Mulched plots supported the greatest weed growth after three years. Stressful environments give a competitive advantage to Idaho fescue in prairie restoration projects. As weedy species increase, growth and survival of Idaho fescue decreases.

Context-dependent pattern and process: the distribution and competitive dynamics of an invasive grass, Brachypodium sylvaticum

“…roemeri), or Roemer's fescue, is a native species found principally in upland prairies west of Cascade Range of Oregon and Washington (Wilson 1996). It is thought to have been common in historic Pacific Northwest prairie ecosystems (Ewing 2002;Jones et al 2008). Festuca roemeri was present only at one of the sites, HBRA, and was the only grass we used in the competition experiment that was not found in close proximity to B. sylvaticum at the field sites.…”

Oak Woodland Restoration: Understory Response to Removal of Encroaching Conifers

“…While prescribed burning is the traditional method of maintaining savannas and prairies in the Pacific Northwest, it is a logistical challenge to implement with regularity or on a large scale. Alternative tools for restoring native vegetation include mowing, tilling, and applying herbicide to undesirable species (Schuller 1997, Tveten and Fonda 1999, Ewing 2002. Fouryear results from a restoration study show that native grasses and forbs may be established by sowing and planting, respectively, following overstory conifer removal from an oak savanna (Vance et al 2006).…”

Abiotic constraints on the competitive ability of exotic and native grasses in a Pacific Northwest prairie

“…In prairie ecosystems, invasive species have been identified as a primary obstacle to successful restoration, and this has been attributed to their ability to competitively exclude native species (Ewing 2002). In particular, theory suggests that invasive species are competitively superior in highquality habitats (i.e., high-nutrient and mesic-moisture conditions), forcing native species to take ''refuge'' in lowquality habitats (Hoopes and Hall 2002;Lowe et al 2003).…”

“…In some cases, native species are able to survive in stressful, low-nutrient environments, but are out-competed by aggressive exotics under high-resource conditions (Huenneke et al 1990; Maron and Connors 1996;Vinton and Burke 1997;Hamilton et al 1999). For example, fertilization treatments that promoted growth in Festuca idahoensis, a perennial grass native to Pacific Northwest prairies, also facilitated success among aggressive exotic species, thereby reducing the positive effects on F. idahoensis (Ewing 2002). Similarly, some native perennial forbs and grasses in northern California were out-competed and replaced by exotic annual grasses in high-nutrient environments, but were able to persist in low-quality habitats (Murphy and Ehrlich 1986).…”