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Feral biofuel crop effects in constructed wet prairie and oak savannah communities
Citation:
WATRUD, L. S., G. KING, M. A. BOLLMAN, J. R. REICHMAN, B. SMITH, C. A. BURDICK, AND E. LEE. Feral biofuel crop effects in constructed wet prairie and oak savannah communities. Presented at Ecological Society of America, Austin, TX, August 07 - 12, 2011.
Impact/Purpose:
We examined the potential effects of feral biofuel crop escapes on constructed plant communities growing in outdoor mesocosms.
Description:
We examined the potential effects of feral biofuel crop escapes on constructed plant communities growing in outdoor mesocosms. Mesocosms containing wet prairie or oak savannah communities were exposed to two temperature levels (ambient and elevated) and two moisture levels (control and drought-stressed). Elevated temperature mesocosms were approximately 2oC warmer than the ambient controls during the summer months. Soil moisture levels for the drought treatment were maintained 20% lower than the controls during the summer dry period. Control soil moisture regimes were based on seasonal soil moisture patterns at nearby native wet prairie and oak savannah communities. Each mesocosm contained three 1.2 m2 pots of equal plant density at the start of the experiment in 2010: the control pot contained six species of native grasses and forbs in triplicate; a second pot contained five natives plus crop sorghum (Sorghum bicolor [cv Piper]) an annual; a third pot contained five natives plus Johnsongrass (Sorghum halepense, a weedy rhizomatous perennial which hybridizes with S. bicolor). At the end of the first growing season in the oak savanna mesocosms, both Sorghum species produced significantly less biomass (P<0.05) than the native perennial grass species (Elymus glaucus). The climate change treatments had a significant negative effect on total community aboveground biomass (P < 0.01). Crop Sorghum seed production was significantly greater (P< 0.06) under the climate change treatments relative to the controls. Both climate change treatments and the type of biofuel species (native, crop sorghum, or Johnsongrass) had significant effects on belowground total fungal biomass (P = 0.004). In particular, crop sorghum pots had lower fungal biomass in soil cores taken from pots that contained only native species or pots that contained Johnsongrass (P< 0.05). Similar trends were observed in the total aboveground biomass data for the wet prairie mesocosms