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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #346162
Title: Plant community dynamics in the shortgrass steppe 24 years after reversal of a grazing exclosure experiment

Author
item Wilmer, Hailey
item Augustine, David
item MILCHUNAS, DANIEL - Colorado State University

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/22/2017
Publication Date: 2/9/2018
Citation: Wilmer, H.N., Augustine, D.J., Milchunas, D.G. 2018. Plant community dynamics in the shortgrass steppe 24 years after reversal of a grazing exclosure experiment. Society for Range Management Meeting Abstracts. Scasta, J., Plechaty, T.R., Derner, J.D., Lake, S., Augustine, D.J., Windh, J.L., Smith, T.L. 2018. Confined cattle feeding trail to validate fecal DNA metabarcoding to inform rangeland free-roaming diet applications. Society for Range Management Meeting Abstracts. Abstract Proceedings of the 71st Society for Range Management, Technical Training, and Trade Show. Jan 28 - Feb 2, 2018, Sparks, NV.

Interpretive Summary:

Technical Abstract: State and Transition Models are important decision-support tools for rangeland managers that suggest directional effects of both long-term grazing imposition and relaxation on plant community composition. However, most studies of the effects of grazing on semiarid rangelands evaluate only one direction of management: response to rest or relaxation of grazing pressure. Here, we study the long-term effects of the imposition and relaxation of cattle grazing on the composition of vegetative community composition on shortgrass steppe. In 1993 we reversed a long-term grazing exclosure study. We opened half of grazing exclosures established in 1939 to moderately stocked, continuous season-long grazing. We built new exclosures in pastures that had been similarly grazed since 1939. In late July of each year we sampled percent cover of all plant species over three dry-wet cycles through 2017. Introduction of grazing into previously ungrazed communities caused them to converge with long-term grazed communities within a decade. Conversely, the abundance of cool-season mid-grasses, and specifically western wheat grass (P. smithii) increased in new exclosures, and converged with long-term exclosures within a decade. Differences between grazed and ungrazed communities increased with successive wet periods through 2016 and declined during dry periods. These findings have direct implications for the revision of State-and-Transition models using empirical data.