Research involving patch burning on the Tallgrass Prairie Preserve has resulted in some interesting findings. For example, prairie chickens seem to be responding positively to patch burning. This finding is important because researchers over the past 25 years have observed a decrease in prairie chicken population throughout the Flint Hills region of Oklahoma and Kansas. Early indications now are that prairie chickens are making a comeback in those acreages on the preserve that have been exposed to a regimen of patch burning.

Fall color on the Tallgrass Prairie

This article explains why this is, based on comments made by Bob Hamilton, director of science and stewardship for the Tallgrass Prairie Preserve, during docent reorientation at the preserve in March.

Male prairie chickens like short grass and a clear landscape to perform their booming dances in the spring to attract the female prairie chicken. The hens, on the other hand, prefer to nest in un-burned patches where they have a much better nesting success due to denser cover. When their chicks hatch, the mother hens like to take them to a burned patch. Prairie chicken chicks require grass hoppers and other invertebrates to grow and survive. The access to insects is much better in burned patches because burning provides an influx of insects, especially grasshoppers.

Hamilton says Sutton researchers have shown that if a hen hatches her brood too far inside an un-burned patch (400 meters, for example) the brood success goes down. It seems the chicks are more susceptible to predators beyond that distance or die from stress trying to get through the thick grasses in search of a burned patch. Prairie chickens are an excellent example of one species that requires different habitat for different reproductive activities within one landscape.

Other grassland birds also require different grassy habitats in order to survive. Upland Sandpipers, for example, will nest on short grass, not in the tall grasses. Henslow?s sparrows on the other hand like big, tall, standing dead vegetation. Research shows that patch burning protects an array of habitats for various species to survive by providing a shifting, patchy mosaic, heterogenic prairie landscape.

The Tallgrass Prairie Preserve and most of the land in Osage County are an extension of the Kansas Flint Hills. Approximately two-thirds of the remaining tallgrass prairie in North America is located in the Flint Hills. The total managed area of the Preserve, counting leased acres and acreage on which The Nature Conservancy has deed restrictions, is about 45,000 acres. Hamilton says the best way to maintain biodiversity is to get those lands and their ecosystems to function as they did before settlement. This also is the optimum way to protect habitat that plant, animal, and natural communities need to survive.

Hamilton says that if you?re going to talk about land management in the Flint Hills, you?ve got to talk about cattle because the Flint Hills comprise a livestock dominated economy. In order for The Nature Conservancy folks to interact with livestock producers in the Flint Hills, the Conservancy has changed its thinking into including a comprehensive cattle research mode. Hamilton said, ?This is a major shift for us.? Some 11,000 acres of the preserve, therefore, will remain as cattle pasture for experimental treatment long term.

Fire is a major aspect of the research taking place at the preserve and involves both the bison and cattle units. Since 1993, patch burning has been used in the bison unit. A research partnership with OSU was initiated in 2001 and involves 7,000 acres in patch burn cattle treatments. This initial research consists of two patch burn pastures in a three-year fire return (1/3 of each pasture burned each year), and two control pastures (entire pasture burned each spring).

Encouraging results have fostered a new phase of the patch burn research which will begin in 2007. In this next phase of research, some pastures will be on a two-year fire-return scheme, some three-year fire-return, and others on a four-year fire-return interval. Some pastures will experience spring burns only and some will experience a spring-summertime burn combination. Hamilton said, ?I?m excited about that.?

Hamilton says that with the new patch burning program, the preserve will switch to a 5-6 month grazing pattern on the cattle unit in place of a 90-day grazing season that has been the custom. He said research typically has found no significant difference in weight gains between annual burning and patch-burning during a 90-day cattle grazing season. By extending the grazing season and burning portions of the cattle unit in the late summer and early fall, the steers this year will have an opportunity to graze on the rich, nutritious new growth that will give them a chance to put on more weight in the late growing season. It is anticipated that 4,500 steers? will pasture on the preserve this year.

Hamilton explained the 21,000-acre bison unit is on a three-year fire-return program which means a third (7,000 acres) of the unit is burned each year. Typically, three or four burns will be conducted in each of the three burning seasons (spring, summer, and fall) rather than burning all 7,000 acres at one time. A randomly selected burn cell, however, may be rejected if that cell doesn?t have enough fuel to burn. An individual cell, therefore, could get selected three out of five years or none out of five years.

Hamilton says a random selection process is used each season because it is felt a helter skelter approach is closer to approximating how fires occurred in nature years ago. He said the whole idea is to seek heterogeneous burning on the preserve. Hamilton said, ?If you fly over the area, you?ll see this, shifting patches, quilty-looking landscape and through the years you can see how this patchwork mosaic moves around the preserve.?

Bison on the preserve are free to roam where they think they might want to go within the confines of the 21,000-acre bison unit. They are attracted to freshly burned areas because the lush re-growth that first appears is high-quality grass. It is natural that all herbivores tend to be more attracted to new growth following a burn than to the un-burned standing growth.

Hamilton said it used to be thought that the ash resulting from burning caused the fertilization effect, but that theory has been proven otherwise. The ash really has no fertilization effect when the phenomenon is all about soil temperature. It seems that by removing thatch, the soil is allowed to warm faster in the spring which kick-starts the microbial activity in the soil. The microorganisms in the soil allow nitrogen to become more available and that is what provides the fertilization effect, not the ash.

4-22-05 Bill Rinehart, Conservancy volunteer (918)299-4104