Gone But Not Forgotten?

Endangered plants re-appear on Mark Twain National Forest following prescribed burn

It is said that for people to thrive in their environment, sometimes all they need is a little stimulation and encouragement. The Mark Twain National Forest has found that the same could be said for running buffalo clover.

Running buffalo clover (Trifolium stoloniferum) is a federally endangered plant that was listed in 1987. It looks a lot like the clover in your backyard, but unlike cultivated clovers, it is native to North America. It derives its name from the theory that historically, it was dependent upon bison or other large ungulates to scarify and spread its seed, and to provide the moderate soil disturbance necessary for its proliferation and spreading.

In 1994-95, the Mark Twain National Forest entered into a Challenge Cost Share Agreement with Missouri Botanical Garden and Northeast Missouri University to introduce populations of running buffalo clover to eleven sites on the National Forest. At each site, seedlings were planted and monitored. Within a few years, the plants at seven of the sites had disappeared, and by 2000, none of the sites had evidence of any running buffalo clover survival. Soon after, monitoring of the sites was discontinued.

However, before the plants disappeared at the introduction sites, some of them had done quite well and not only flowered, but produced seed. There were many theories regarding why the plants had disappeared at the sites, but the most prevalent theory was that the conditions at the introduction sites had deteriorated due to a lack of management.

Most of the research on running buffalo clover indicated that, for long-term survival, the plants require filtered sunlight and periodic moderate soil disturbance. However, the introduction sites on the Mark Twain National Forest had not been disturbed and most were heavily shaded.

Acting on a suspicion that seeds at one of the introduction sites may still be viable, the Potosi District of the Mark Twain National Forest decided to conduct a burn at one of the introduction sites. It had been over 8 years since running buffalo clover had been observed at the site, but it was hoped that a prescribed burn may stimulate dormant seeds still in the soil and encourage them to germinate.

In March 2008, a small five-acre burn was conducted on the site. Prior to this burn, no active management (e.g. burning, thinning, etc.) had occurred at the site. Then, biologists waited. Finally, after the spring burn followed by a growing season of record rainfall, it was time to go check the site.

On September 17, 2008, biologists returned to the site, and to their pleasant surprise, were greeted by healthy, vibrant and growing running buffalo clover seedlings. The prescribed burn had worked! Biologists counted several seedlings growing in many of the introduction plots in the burned area.

Although this was a very small burn on the Mark Twain National Forest, in had a very large impact upon the biodiversity of the National Forest and Missouri. With the re-appearance of running buffalo clover at this site, the number of populations of this endangered plant on the Mark Twain National Forest now equals one, and it represents one-eighth of the statewide population.

Managers of the Mark Twain National Forest are now discussing options regarding how to best manage this site, and are considering burns at some of the other historic introduction sites to see if this good luck can be repeated. Stay tuned!