Long term monitoring of Kentucky Clover in Franklin County @T. LIttlefield
Big news for native clover conservation in the Bluegrass State! Several years of conservation collaboration has resulted in the first transplants of the globally rare Kentucky Clover back into the Bluegrass Woodlands this fall! This endangered clover was discovered (2010) and described (2013) recently and was known from only two privately owned limestone woodlands in the Inner bluegrass of Kentucky. Since its discovery, the Kentucky clover had disappeared from both sites despite annual monitoring and management efforts conducted by Office of Kentucky Nature Preserves Botanist Tara Littlefield and KDFWR biologist Joe Lacefield. Luckily, seed collection and propagation efforts were successful due to our collaborative efforts with Valerie Pence, Kristine Lindsey, and Mairead Kennedy from the Cincinnati zoo CREWs plant program, among many other partners, and the first batch of Kentucky Clover plants was transferred to OKNP in order to transplant into high quality, managed limestone woodlands.
Mairead Kennedy and Valerie Pence present propagated Kentucky Clover Plants at CREW @T. Littlefield
CREW staff have developed techniques to propagate Kentucky Clover @T. Littlefield
After several years of managing transplant sites for removal of invasive species such as bush honeysuckle (Lonicera maackii), OKNP staff and partners transplanted 75 Kentucky clover plants back into the original Franklin county site as well as transplanted new populations into 3 additional protected high-quality natural areas in Franklin county. OKNP botanists and partners will be monitoring the success of these transplants over the next several years and conducting quantitative studies on how best to manage for this rare clover and its unique limestone woodland habitat.
Clover Power! @ T. Littlefield
Limestone woodlands in Franklin county @T. Littlefield
Brian Baker (Cove Spring staff) assists in KY Clover planting @T. Littlefield
OKNP biologists and GIS staff (from L to R): Vanessa Voelker, Devin Rodger, Rachel Cook, Heidi Braunreiter, Courtney Hayes, Tara Littlefield, and Lexi Schoenlaub. @ Brain Baker
The power of partnership is key to conserving rare plants and the collaborative approach of the Kentucky Plant Conservation Alliance has made these recovery efforts possible. if you would like to help with these or other plant conservation alliance projects, please contact tara.littlefield@ky.gov.
By: Heidi Braunreiter, Office of Kentucky Nature Preserves Plant Ecologist
OKNP botanist conducting running buffalo clover survey in 2019 along Boone Creek in Clark County. Photo by Heidi Braunreiter.
Running Buffalo Clover (Trifolium stoloniferum) is a perennial clover with showy white flowers and leaves divided into three leaflets, and was historically native to several eastern and midwestern U.S. states. Based on numerous references to clovers in historical literature, it is believed to have been abundant across its historical range in pre-settlement times, which included the Bluegrass Region of Kentucky (Campbell et al. 1988). However by 1900, its extent had drastically reduced, and only five populations in total remained (Brooks, 1983). Throughout the 20th century, there were numerous fruitless attempts to relocate populations, which lead scientists to believe the species was extirpated from states where it was historically common. Finally, in 1983 populations were relocated in West Virginia and Indiana, as well as in northern Kentucky in 1987 (Campbell et al. 1988). With so few populations known, the U.S. Fish and Wildlife Service (USFWS) opted to list the species in 1987 as ‘federally endangered,’ because it was at a high risk of extinction (USWFS 2007).
The decline of running buffalo clover is believed to have been caused by a combination of factors: as land was settled, habitat destruction ensued and competition from non-native invasive species became a problem (Campbell et al. 1988). Another factor was the loss of the American Bison on the landscape. Historical observations noted the clover’s preference for sites where American Bison congregated (Bartgis 1985). Bison likely provided a means of fertilizer, seed scarification, seed dispersal, and the periodic disturbance regime necessary for the running buffalo clover’s life cycle (Campbell et al. 1988). The loss of bison from the landscape would have dramatically affected the species’ propagation.
Running buffalo clover in a cemetery in Boone County, Kentucky. Photo by Heidi Braunreiter.
Today, you will find running buffalo clover in areas that have periodical disturbances mimicking bison; for example, along trails where plants get trampled, in old estate lawns or cemeteries that are regularly mowed, and on stream terraces with occasional flooding events. Running buffalo clover also prefers dappled sunlight in a forested setting. If the forest canopy becomes either too closed or too open, running buffalo clover populations tend to decline in number as it does not tolerate full shade or full sun (USFWS 2021).
Over the past two decades, the Office of Kentucky Nature Preserves (OKNP) has conducted monitoring on running buffalo clover populations in Kentucky in order to look at population trends and manage for non-native invasive plants. Over this time, many new county records were discovered through targeted searches of historical estates, cemeteries, and stream restoration efforts in the Bluegrass Region. Several successful propagation and introductions efforts have also occurred over the years, for example, new populations were introduced and are now self-sufficient at Shaker Village at Pleasant Hill in Mercer County and Taylor Fork Ecological Area in Madison County.
In 2019, running buffalo clover was proposed for delisting by the USFWS, as many populations had been discovered since its initial listing over 30 years prior. In response to the 2019 proposed delisting, OKNP conducted a state-wide assessment of our running buffalo clover populations. Despite set-backs from the pandemic, we were able to survey 61 populations, which covered the majority of the known extant populations in Kentucky. Sites not included in the assessment were already determined to be extirpated, or inaccessible. Most populations in Kentucky occur on private lands, and although obtaining access to private lands can be difficult, we have been grateful for the curiosity, interest, and enthusiastic response from many property owners. Overall, population trends in Kentucky show approximately half of the populations as stable or increasing in size while the other half of populations are declining in size or extirpated (Table 1). Figure 1 shows an updated range map of extant running buffalo clover populations in Kentucky.
Table 1. Population trends of running buffalo clover in Kentucky during the 2019-2020 statewide survey.
A huge success that came out of the 2019-2020 statewide survey was the discovery of the largest running buffalo clover population in Kentucky. On the Mt. Folly Farm in Clark County, a population of over 6,000 plants was counted along the Upper Howards Creek. Other large populations of running buffalo clover in the state top out around 1,000 to 2,000 plants. The significance of this population led to the creation of a new Registered Natural Area with OKNP at Mt. Folly Farm. The clover occurs in the floodplain of the creek in cattle pastures and riparian woods. This site holds potential for future research as it has running buffalo clover in areas with and without a cattle-grazing regime.
As of September 2021, running buffalo clover was delisted by USFWS as they believe there are a sufficient number of populations occurring on publicly owned and managed lands to sustain the species’ viability (USWFS 2021). As of 2020, 175 extant populations occur across its range in Indiana, Kentucky, Missouri, Ohio, Pennsylvania and West Virginia, and biologists in these states discover new populations every year. Within Kentucky, many populations occur on Wildlife Management Areas where stream restoration projects are ongoing. The key to the future success of this plant is the continued management of populations to keep invasive plants at bay and the continued implementation of appropriate disturbance regimes, be that mowing, grazing, or trampling.
If you are interested in adopting a running buffalo clover population in Kentucky to do yearly checkups to remove invasive species, please contact me! heidi.braunreiter@ky.gov.
Figure 1. Extant range of running buffalo clover in Kentucky as of February 2021.
Bibliography
Bartgis, R. 1985. Rediscovery of Trifolium stoloniferum Muhl. ex A. Eaton. Rhodora 87:425–429.
Brooks, R. 1983. Trifolium stoloniferum, Running buffalo clover: Description, distribution, and current status. Rhodora 85:343–354.
Campbell, J.J.N., M. Evans, M.E. Medley, and N.L. Taylor. 1988. Buffalo clovers in Kentucky (Trifoliumstoloniferum and Trifolium reflexum) – Historical records, presettlement environment, rediscovery, endangered status, cultivation and chromosome number. Rhodora 90:399–418.
USFWS. 2007. U.S. Fish & Wildlife Service: Running Buffalo Clover (Trifolium stoloniferum) Recovery Plan: First Revision. Department of the Interior, U. S. Fish and Wildlife Service, Great Lakes-Big Rivers Region (Region 3), Fort Snelling, MN.
Clovers (Trifolium sp.) are well recognized by the public primarily because of their role as a forage crop and lawn weed. In Kentucky, we have 12 species of clover, but only 3 are native to our state, Kentucky Clover (Trifolium kentuckiense), running buffalo clover (Trifolium stoloniferum), and buffalo clover (Trifolium reflexum). All of our native clovers have declined greatly since European settlement and are state or federally listed as threatened or endangered. Historic accounts from pioneers and historic collections of native clovers indicate that our native clovers may have been more common in the woodlands of our state, particularly in the Bluegrass Region. Our native clovers have common names associated with buffalo since their associated habitat historically occurred mostly along buffalo/animal trails through the forest, which the Bluegrass Region is known for, large ungulates grazing on the grasses and forbs in our woodland systems.
In an effort to increase coordination and collaboration focused on priority native clover (Trifolium sp.) conservation projects in Kentucky, close to 30 botanists, ecologists, researchers, students, and land managers met in late February 2021 to discuss all things native clover (Trifolium sp.). Species of focus included the globally rare and newly described Kentucky Clover (Trifolium kentuckiense), the federally endangered running buffalo clover (Trifolium stoloniferum), and the state threatened buffalo clover (Trifolium reflexum).
The Kentucky Plant Conservation Alliance coordinated the meeting and facilitators from the Office of Kentucky Nature Preserves, Virginia Tech University, Eastern Kentucky University, Austin Peay University, University of Michigan, and Cincinnati Zoo presented information on the current status (population ranks and trends), current conservation measures (land protection and management efforts), current research (life history, management needs, and genetics), as well as seedbanking and propagation efforts The goal of the group is to work more collaboratively together to prevent the extinction or extirpation of these native clovers. If you missed the meeting, here is the agenda, and recorded version and meeting notes
If you are interested in joining our clover conservation group and helping with some of the existing working groups involving research, monitoring, management, propagation, seedbanking, and fundraising for priority clover projects, please contact Tara Littlefield, tara.littlefield@ky.gov. We will continue to provide updates on existing Trifolium projects through the ladyslipper newsletter and at the Kentucky Botanical Symposium this fall. We will also be organizing various volunteer days this summer to help with monitoring and managing running buffalo clover, so be on the lookout for future volunteer work day announcements.
Clovers are
an odd group of plants caught between agriculture and agronomy, especially in
the Bluegrass. Agronomists and cattlemen find clovers important for their
nitrogen contribution and nutritive value to livestock. Horse owners fear
clover for the fungal pathogen behind slobbers. Wildlife managers use them for
food plots. Of the roadside clovers, most came to Kentucky with settlers (Ball
et al., 2015; Bryson and DeFelice, 2009). Those red and white clovers came with
the tall fescue and Kentucky bluegrass. These species play an important role in
Kentucky agriculture; however, the horse parks and cattle farms have replaced
the natural ecosystems in the state (Noss, 2013; Campbell, 2014; Campbell, 2010).
In addition
to these introduced species, Kentucky has three prominent native clovers:
annual buffalo clover, running buffalo clover, and Kentucky clover (Vincent,
2001). Although collections of the native clovers have been made across Kentucky,
it is really very uncommon to find these populations unless one knows where
someone else has previously found it. It is unlikely that the reader will find
these species in the local park or native area.
Annual
buffalo clover (Trifolium reflexum),
is spread throughout most of the eastern United States. The beautiful blooms
have led to its potential as a horticultural species (Quesenberry et al.,
2003). Of the native clovers, the genetics of the flowering in annual buffalo
clover have been the most explored: red, white, and pink flowers (Quesenberry
et al., 2003). At one point, it was favored over naturalized white clover in unimproved
grazing lands (Killebrew, 1898).
Running buffalo clover (Trifolium stoloniferum) is a perennial species limited to the Ohio River Valley and Missouri. Plants spread on thick runners like strawberries. The species was investigated as a potential forage in the 1990s, and has been the subject of interest for herbivory dynamics in the eastern United States. The thick seed coat requires scarification in order for the seed to germinate (Kubesch, 2018; Sustar, 2017). Hoof action has been proposed as a driver in the ecology of the species, but a general disturbance regime seems necessary for the species to persist in the landscape (Kubesch, 2018). With some sandpaper and a few hours of free time, seed can be scarified. Running buffalo clover grows readily in the greenhouse.
Ashland, The Henry Clay Estate in Lexington is having a clean-up day on Saturday, November 2nd from 9:00am-12:00pm. Join Heidi Braunreiter with Kentucky Nature Preserves to help pull winter-creeper from populations of running buffalo clover populations on the estate. Ashland will be providing coffee and krispy kreme donuts in the morning and Donato’s pizza at noon. Bring gloves, water, knee pads, and pruners if you have them.
Federally-endangered plant running buffalo clover
Running buffalo clover (Trifolium stoloniferum) is a federally-endangered plant that requires periodic disturbance and a partially shaded canopy. Historically, it occurred along bison trails but today it is most commonly found along forested stream terraces, trails, and lawns of old homesteads. Running buffalo clover was found at Ashland in 1989 as part of Kentucky Nature Preserves effort to survey lawns of historical homes to locate more populations. The Ashland staff have utilized mowing as a tool to create disturbance and benefit the growth of their running buffalo clover. However, an invasive vine called winter-creeper has become established in many of the running buffalo clover patches at the estate. Winter-creeper (Euonymus fortunei) is an aggresive weed that can out-compete native flora. We will be pulling winter-creeper around the patches of running buffalo clover in an effort to keep it from taking over.
