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ARS Home » Plains Area » El Reno, Oklahoma » Oklahoma and Central Plains Agricultural Research Center » Livestock, Forage and Pasture Management Research Unit » Research » Publications at this Location » Publication #398267

Research Project: Sustaining Southern Plains Landscapes through Improved Plant Genetics and Sound Forage-Livestock Production Systems

Location: Livestock, Forage and Pasture Management Research Unit

Title: Assessment of Oklahoma phlox in the Gypsum Hills of northwestern Oklahoma and southern Kansas

Author
item SPRINGER, TIMOTHY - Retired ARS Employee
item Moffet, Corey

Submitted to: Oklahoma Native Plant Record
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Oklahoma phlox (Phlox oklahomensis) occurs within the tall grass prairie of the southern Flint Hills of Kansas and other populations occur within the southern mixed grass prairie of the Gypsum Hills of northwestern Oklahoma and southern Kansas. Oklahoma phlox was once considered a threatened plant species due to its limited distribution range. The first assessment of Oklahoma phlox occurred in 1980-1982, and a second assessment occurred in 2001-2002. Since 1982 two major wildfires and several droughts have occurred in its distribution range. Scientist at the Southern Plains Range Research Station, USDA-ARS, Woodward, Oklahoma conducted another census of the species in 2021-2022 to access the current status of the species. In addition, they used a geographic information system (GIS) to identify factors that influence the likelihood of finding Oklahoma phlox in the region. The census found that the status of Oklahoma phlox has not changed significantly over the past 40 years. Populations thrive in areas where the fire interval was greater than 5 years, and it commonly occurs on the upper elevations of the landscape on hilltops and/or ridges where the slope was greater than 7%. Although plants were observed on all landscape exposures, populations occur more frequently on west and northwest facing slopes.

Technical Abstract: Phlox oklahomensis Wherry, also known as Oklahoma phlox, occurs within the tall grass prairie of the southern Flint Hills of Kansas and other populations occur within the southern mixed grass prairie of the Gypsum Hills of northwestern Oklahoma and southern Kansas. It has been 40 years since the initial census of Oklahoma phlox in the Gypsum Hills of northwestern Oklahoma and Southern Kansas. Since that time two major wildfires and several droughts have occurred in its distribution range. The goal of this research was to compare the 1982 and 2001-2002 censuses of Oklahoma phlox in the Gypsum Hills of northwestern Oklahoma and adjacent Kansas to that of today and assess the current status of the species. In addition, we used a geographic information system (GIS) to identify factors that influence the likelihood of finding Oklahoma phlox in the region. The census found that the status of Oklahoma phlox has not changed significantly over the past 40 years. Populations thrive in areas where the fire interval is >5 years, and it commonly occurs on the upper elevations of the landscape on hilltops and/or ridges where the slope is > 7%. Although plants were observed on all landscape exposures, populations occur more frequently on west and northwest facing slopes. The authors recommend a S2S3 ranking for Oklahoma Natural Heritage Inventory.