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Title: Drought and grazing effects on Oklahoma phlox (Polemoniaceae, Phlox oklahomensis)

Author
item Springer, Timothy
item Gunter, Stacey
item TYRL, RONALD - Oklahoma State University
item NIGHSWONGER, PAUL - Northwestern Oklahoma State University

Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/11/2013
Publication Date: 6/20/2013
Publication URL: http://handle.nal.usda.gov/10113/56902
Citation: Springer, T.L., Gunter, S.A., Tyrl, R.J., Nighswonger, P.F. 2013. Drought and grazing effects on Oklahoma phlox (Polemoniaceae, Phlox oklahomensis). American Journal of Plant Sciences. 4:9-13.

Interpretive Summary: Drought is a common feature of every landscape and can last from a few months to several years or even decades. Mitigating the impacts of drought through planning and preparedness would lessen drought effects on plant communities. When drought and over-stocking are combined, the health of the community is at risk. The Oklahoma Phlox (Phlox oklahomensis Wherry) is endemic to Butler, Chautauqua, Comanche, Cowley, and Elk Counties of Kansas, and Woods and Woodward Counties of Oklahoma and is considered a threatened plant species. It comprises populations of a few scattered individuals to several hundred on mixed prairie sites in Oklahoma where cow-calf production is the common agricultural enterprise. On the basis of antidotal evidence, prolonged heavy stocking rates and drought would disrupt the reproductive cycle, severely limiting seed production and recruitment of new individuals to populations. During drought periods, livestock managers should use below moderate stocking rates to ensure rapid recovery of prairie plants once the drought ends. This recommendation would likely sustain prairie sites during long-term (longer than 10 years) droughts as well. Proper grazing management through drought will ensure the health of a thriving prairie community.

Technical Abstract: Oklahoma phlox (Phlox oklahomensis Wherry) is endemic to Butler, Chautauqua, Comanche, Cowley, and Elk Counties of Kansas and Woods and Woodward Counties of Oklahoma. The species comprises populations of a few scattered individuals to several hundred in mixed-grass prairie sites in Oklahoma where cow-calf production is the common agricultural enterprise. It has successfully withstood periods of short-term drought (1 to 4 years) under light to moderate continuous stocking rates (41 to 52 animal unit days per hectare). Under heavy continuous stocking rates and/or prolonged drought, populations of P. oklahomensis tend to decrease in size and number and may disappear in some localities. Prolonged heavy stocking rates and drought will disrupt the reproductive cycle, severely limiting seed production and recruitment of new individuals to populations. During drought periods, livestock managers should use lighter stocking rates or deferred grazing to ensure rapid recovery of all prairie plants, including P. oklahomensis, once the drought ends. This recommendation would likely sustain prairie sites during long-term (longer than 10 years) droughts as well.