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Abstract
The objective of this experiment was to test the hypotheses that 1) simulated herbivory stimulates increased biomass production in spiny hackberry (
Celtis pallida), but decreases biomass production in blackbrush acacia (
Acacia rigidula) compared to unbrowsed plants and 2) thorn density and length increase in blackbrush acacia to a greater extent than in spiny hackberry in response to tissue removal. Blackbrush acacia shrubs defoliated repeatedly at the 75 percent level produced about 66 percent more biomass than control shrubs, while shrubs receiving 100 percent repeat defoliation treatments produced double the biomass as control shrubs (p < 0.05), suggesting overcompensation. Spiny hackberry repeat defoliated shrub biomass production was double control shrub production at 25 percent treatment levels and 81 percent higher in repeat defoliated shrubs at 50 percent defoliation levels relative to control shrubs (p < 0.05). Biomass production during the third and fourth defoliation events was 90 percent lower than (p < 0.05) biomass removed in the initial defoliation. New twig and thorn production occurred only in 2003, but only in blackbrush acacia. These results suggest that spiny hackberry, a highly palatable shrub, is negatively impacted at high defoliation intensity, while the less palatable shrub, blackbrush acacia, responds to intense defoliation with increased biomass production.
Parent Publication
Citation
Teaschner, Terri B.; Fulbright, Timothy E. 2007. Shrub biomass production following simulated herbivory: A test of the compensatory growth hypothesis. In: Sosebee, Ronald E.; Wester, David B.; Britton, Carlton M.; McArthur, E. Durant; Kitchen, Stanley G., comps. Proceedings: Shrubland dynamics -- fire and water; 2004 August 10-12; Lubbock, TX. Proceedings RMRS-P-47. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 107-111.
