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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #279134
Title: Mechanisms of competitive suppression of native grasses by johnsongrass

Author
item MECKEL, HEATHER - Texas State University
item SCHWINNING, SUSAN - Texas State University
item Fay, Philip

Submitted to: Ecological Society of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/28/2012
Publication Date: 8/5/2012
Citation: Meckel, H., Schwinning, S., Fay, P.A. 2012. Mechanisms of competitive suppression of native grasses by johnsongrass. In: Proceedings of the Ecological Society of America, November 11-14, 2012, Knoxville, Tennessee. 2012 CDROM.

Interpretive Summary:

Technical Abstract: Native perennial grasses are widely considered alternatives to corn for biofuel production. However, there is concern that nitrogen fertilization of perennial grasses makes them just as vulnerable to noxious weeds. One of the most problematic weeds in grasslands is the C4 perennial grass Johnsongrass (Sorghum halepense). We conducted a greenhouse study to investigate the mechanistic basis by which Johnsongrass may outcompete three native C4 grasses, big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), and the biofuel crop, switchgrass (Panicum virgatum). We hypothesized that Johnsongrass suppresses native grass species due to differences in the allocation of biomass between roots, stems and leaves. Grasses were planted as seeds in 1 m tall, 10 cm wide pots (15 liters) and grown for six months. The four species were grown at two levels of nitrogen (N) (+0.14 g and +0.42 g slow-release N fertilizer per pot in 70/30 sand to topsoil), either alone or in combination with Johnsongrass in a full factorial randomized complete block design. Each month, leaf gas exchange was measured and a subset of plants was harvested to measure biomass allocation to leaves, stems, reproductive tissues, and roots. Data were analyzed using ANOVA.