Submitted to: Proceedings of the National Conference on Grazing Lands
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 2000
Publication Date: December 15, 2000
Citation: Northup, B.K., Daniel, J.A. 2000. Impact of climate and management on species composition of southern tallgrass prairie, Oklahoma. Proceedings of the National Conference on Grazing Lands. pp. 693-700. Interpretive Summary: ABSTRACT ONLY
Technical Abstract: A study was undertaken at the USDA-ARS Grazinglands Research Laboratory to define changes in species composition of a southern tallgrass prairie in Oklahoma over a 10-year period (1985-95) in response to management and climate. In each year, contributions of different functional groups of herbaceous species to community composition were defined on managed 1.6 ha experimental paddocks. Management regimes were: 1) unmanaged (25 years) relict area; 2) heavily grazed by stocker cattle (82 animal unit day [AUD] grazing/year); 3) lightly grazed by stocker cattle (46 AUD/year); 4) lightly grazed with annual applications of broadleaf herbicide and fertilizer. Ungrazed exclosures were established within each grazed paddock. Species groups were: 1) dominant warm-season grasses (4 species); 2) shortgrasses (4 species); 3) other warm-season grasses (11 less-common species); 4) annual bromes (2 species); 5) other cool-season grasses (5 species); and 6) forbs (17 species). Data (% composition) were analyzed by principal components and correspondence analyses. Both grazing pressures caused divergences in species composition beginning in 1990, and similarity in floristic structure with ungrazed exclosures had not returned by 1995. This change was principally due to dry conditions in fall 1989 and spring 1990, and the applied grazing pressures. Dominant warm-season grasses declined while shortgrasses, annual bromes and cool-season grasses increased in importance. There was no advantage in fertilizer and herbicide applications, as weedy warm-season grasses became more prevalent, and areas not grazed for 25 years supported a species composition completely different from grazed areas.