Effect of Imazapic on Cheatgrassand Native Plants in Wyoming Big Sagebrush Restoration for Gunnison Sage-grouse
William L. Baker
Jim Garner
Peggy Lyon
Imazapic has shown potential to control invasive weeds, such as cheatgrass (Bromus tectorum L.), during ecological restoration, but effects on non-target native plants are poorly known. In a replicated field experiment, as part of restoration for Gunnison sage-grouse (Centrocercus minimus) in Colorado, imazapic was applied in the fall at a high rate (175 g/ha) to control cheatgrass in mowed Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young). Cheatgrass was reduced, but only by 67%, and non-native forbs were reduced by 80% by the following summer. However, native forbs also declined (by 84%). Two native grasses declined, but others were not affected. Damage to native forbs would likely be detrimental to sage-grouse and other wildlife if it occurred over large areas. Perhaps application of imazapic just to cheatgrass plants or patches and application earlier in restoration would allow control with less adverse effects on native forbs.
Old World Climbing Fern (Lygodium microphyllum) Invasion in Hurricane Caused Treefalls
Ryan L. Lynch
Hongjun Chen
Laura A. Brandt
Frank J. Mazzotti
We examined effects of a natural disturbance (hurricanes) on potential invasion of tree islands by an exotic plant (Old World climbing fern, Lygodium microphyllum) in the Arthur R. Marshall Loxahatchee National Wildlife Refuge, Florida. Three major hurricanes in 2004 and 2005 caused varying degrees of impacts to trees on tree islands within the Refuge. Physical impacts of hurricanes were hypothesized to promote invasion and growth of L. microphyllum. We compared presence and density of L. microphyllum in plots of disturbed soil created by hurricane-caused treefalls to randomly selected non-disturbed plots on 12 tree islands. We also examined relationships between disturbed area size, canopy cover, and presence of standing water on presence and density of L. microphyllum. Lygodium microphyllum was present in significantly more treefall plots than random non-treefall plots (76% of the treefall plots (N=55) and only 14% of random non-treefall plots (N=55)). Density of L. microphyllum was higher in treefall plots compared to random non-disturbed plots (6.0 stems per m² for treefall plots; 0.5 stems per m² for random non-disturbed plots), and L. microphyllum density was correlated with disturbed area size (P = 0.005). Lygodium microphyllum presence in treefall sites was significantly related to canopy cover and presence of water: it was present in five times more treefalls with water than those without. These results suggest that disturbances, such as hurricanes, that result in canopy openings and the creation of disturbed areas with standing water contribute to the ability of L. microphyllum to invade natural areas.