Kris Lah, Endangered Species Coordinator at the Service's Chicago Illinois Field Office, carries a flat of leafy prairie clover seedlings to be planted in the field.

Kris Lah, of the Service's Chicago Field Office, shows a browse exclusion cage set over a plot of out-planted leafy prairie clover plugs. USFWS Image by Michael Redmer.

Biologists Dan Kirk and Rebecca Lira (Illinois Department of Natural Resources) plant and collect data on leafy prairie clover seedlings. USFWS Image by Michael Redmer.

Biologists Dan Kirk and Rebecca Lira (Illinois Department of Natural Resources) planting and collecting data on leafy prairie clover seedlings. USFWS Image by Michael Redmer.

Biologist Dan Kirk (Illinois Department of Natural Resources; left) and Kris Lah (USFWS) plant leafy prairie clover seedlings. USFWS Image by Michael Redmer.

Natural Areas Preservation Specialist Kim Roman (Illinois Nature Preserves Commission) carries a flat of leafy prairie clover seedlings to be planted in the field. USFWS Image by Michael Redmer.

A multi-partner effort being led by the Chicago Illinois Field Office to restore the federally endangered leafy prairie clover (Dalea foliosa) in Illinois recently took a big step when over 2,500 seedlings were planted at sites in two counties in the Chicago metropolitan area.

The leafy prairie clover is restricted to three separate regions of the eastern United States: central Tennessee, north-central Alabama, and northeastern Illinois. A perennial forb, the leafy prairie-clover occurs only in open habitats with thin, calcareous soils.  In Tennessee and Alabama, the preferred habitat is limestone or dolomite glades, but in Illinois, this plant is restricted to a very rare plant community, dolomite prairie.  Dolomite prairie is characterized by a suite of specific plants (some of them rare) growing in areas where dolomite bedrock forms exposed or "paved" areas.  It has been estimated that as little as 600 acres of high quality dolomite prairie remain in Illinois.  Only seven surviving populations of leafy prairie-clover remain in the state, with populations ranging in size from a few hundred to several thousand individuals.  Not all of these populations are protected, however, and records indicate that several additional, historically known populations have been extirpated.  All these sites are or were once dolomite prairies.

In 2005, the Service's Chicago Illinois Field Office partnered with the US Forest Service (Midewin National Tallgrass Prairie), the Illinois Department of Natural Resources as well as the Forest Preserve Districts of Kane and Will counties to plan a project that may lead to recovery of the leafy prairie clover at the northern end of its range.   

The first and most costly step was to secure funding to remove invasive species from what would otherwise be suitable habitat for the leafy prairie clover.  Late in 2005, the Chicago Field Office submitted a proposal and received a grant form the National Fish and Wildlife Foundation that would primarily help restore dolomite prairies where leafy prairie clover could be reintroduced.  Funding from the National Fish and Wildlife Foundation is being matched by partners in the project by 1.5 times the grant amount.  Restoration and invasive species removal took place up until the winter of 2007-2008.

Previous experiences of conservation biologists who have worked with the leafy prairie clover indicate that it is not readily established by simply collecting and broadcasting seeds, and that planting of 1-year-old seedlings may be more successful.  Thus, the second step was to collect seeds from the seven remaining Illinois populations of leafy prairie clover.  Ripe seeds collected in the autumns of 2006 and 2007 were then transferred to Midewin National Tallgrass Prairie because it has state-of-the-art facilities for propagating and handling native plants and their seeds as part of its ecological restoration program. Midewin's staff has considerable experience propagating a wide range of native plant materials and establishing these plants in restored habitats.  Plants grown at Midewin would then become available for reintroduction in habitat restorations, augmentation of extant populations, as well as for establishment of a captive population from which seeds could be harvested in the future.

Leafy prairie clover is a favorite food of rabbits and deer, and in some years browsing by these animals can severely limit reproductive output by the plants.  Thus, when the first batch of seedling leafy prairie clovers was 1 year of age (the age at which the greatest survival of outplanted seedlings is expected), project partners held joint work days to construct sturdy browse exclosure cages.  The cages would eventually be placed over select plots of outplanted leafy prairie clovers.    

The final step in 2008 occurred during the first two weeks of July, when over 2,500 seedlings were planted at sites that have appropriate dolomite habitat and that are within the historic range of the leafy prairie clover.  Noteworthy was that over 1,100 leafy prairie clover were introduced into a state-owned conservation area that lacked a known population, but that has extensive habitat.  Leafy prairie clover was also returned to a preserve in Kane County that is believed to be the species type locality (the type locality is a site where a species is first discovered when it is described and given a scientific name), but where no individual has been seen since the late 1800s when the species was discovered.

A second cohort of leafy prairie clover seedlings is being grown by the US Forest Service, and should allow additional augmentation of both existing and newly introduced populations to take place in 2009.

Written by Michael Redmer and Kristopher Lah