Wednesday, November 15, 2006 - 9:30 AM
227-3
Effects of Different Cover Crops (Bridge Species) on Non-Native Weed and Prairie Grass Abundance.
Military training can lead to disturbed soil conditions that are prone to non-native weed invasion and erosion. We hypothesized that cover crops could revegetate disturbed areas and both decrease non-native weed invasion and increase the establishment of dominant C4 prairie grasses. Specifically, we predicted that a C3 cover species, western wheatgrass (Pascopyrum smithii), would directly increase establishment of dominant C4 prairie grasses by acting as a nurse plant, and that western wheatgrass would indirectly increase establishment of C4 prairie grasses by inhibiting non-native weeds. Smooth brome (Bromus inermis) is also commonly planted after a disturbance, and we wanted to compare the effects of smooth brome to that of western wheatgrass. To test these predictions we factorially manipulated both the presence of cover species (no cover species; western wheatgrass; smooth brome) and the abundance of non-native weedy species (no non-native species sown; low density of non-native species sown; 10x the low density of non-native species sown), and we also sowed four species of dominant C4 prairie grass into each treatment. The experiment was begun in September 2005 in a greenhouse using soil collected from Fort Riley, Kansas . Our results as of April 2006 show that western wheatgrass and smooth brome did not significantly affect the percent groundcover of non-native weeds or C4 prairie grasses. However, successively higher sowing densities of non-native weedy species did decrease the percent groundcover of C4 prairie grasses (P < 0.05). The effects of non-native weedy species may have been due to quick growth and resource pre-emption since higher weed sowing densities caused both soil moisture and light levels to decrease significantly. There were no significant interactive effects of weed sowing density and C3 cover crop identity. Overall, our results suggest that non-native weeds suppress the establishment of dominant C4 prairie grasses.
Recorded presentation