ARS | Publication request: Are there benefits to mowing intact Wyoming big sagebrush communities? An evaluation from southeastern Oregon

Submitted to: Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 21, 2011
Publication Date: September 1, 2011
Repository URL: http://hdl.handle.net/10113/50007
Citation: Davies, K.W., Bates, J.D., Nafus, A. 2011. Are there benefits to mowing intact Wyoming big sagebrush communities? An evaluation from southeastern Oregon. Environmental Management. 48:539-546.

Interpretive Summary: Mowing treatments are commonly applied to big sagebrush plant communities to presumably improve wildlife habitat and increase forage production. However, information is lacking to determine if these benefits are realized when mowing is applied to relatively intact Wyoming big sagebrush plant communities. We measured the response of vegetation characteristics to mowing for three years post-mowing. The presumed increase in desirable perennial vegetation following mowing did not occur. However, exotic annual grasses that can degrade wildlife habitat and decrease forage production did increase following mowing. These results question the validity of the assumed benefits of mowing in Wyoming big sagebrush plant communities. This information is critical to determine if mowing Wyoming big sagebrush plant communities will meet management objectives for wildlife habitat and forage production.

Technical Abstract: Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle & Young) communities frequently are mowed in an attempt to increase perennial herbaceous vegetation. However, there is limited information as to whether expected benefits of mowing are realized when applied to Wyoming big sagebrush communities with intact understory vegetation. We compared vegetation and soil nutrient concentrations in mowed and undisturbed reference plots in Wyoming big sagebrush plant communities at eight sites for three years post-treatment. Mowing generally did not increase perennial herbaceous vegetation cover, density, or biomass production (p > 0.05). Annual forbs and exotic annual grasses were generally greater in the mowed compared to the reference treatment (p < 0.05). By the third year post-treatment annual forb and annual grass biomass production was more than 9- and 7-fold higher in the mowed than reference treatment, respectively. Our results imply that the application of mowing treatments in Wyoming big sagebrush plant communities does not increase perennial herbaceous vegetation, but may increase the risk that exotic annual grasses will dominate the herbaceous vegetation. We suggest that mowing Wyoming big sagebrush communities with intact understories does not produce the expected benefits. However, the applicability of our results to Wyoming big sagebrush communities with greater sagebrush cover and/or degraded understories needs to be evaluated.