Gartner, F. Robert. 1975. Wind Cave National Park Grassland Ecology. South Dakota State University. 29 p. + Appendixes.
Summary and Conclusions
- Prescribed burning in the grassland area of Wind Cave National Park greatly reduced total fuels and created natural firebreaks suitable for controlling wildfires.
- Prescribed burning in grasslands similar to those studied can be safely accomplished with proper equipment and adequate manpower under a wide range of fuel moisture and climatic conditions.
- Burning should be conducted in late winter or spring when air temperature is 70° F or lower, relative humidity 30% or more, and wind speeds not greater than 10 to 12 mph. Higher wind speeds are acceptable if burning is conducted toward an existing road.
- Late summer or fall burning may be necessary in some areas of the Park or because of labor availability at that time of year. However, burning at this season should only be done when seasonal precipitation is above normal.
- Moisture content of the mulch layer should be sufficiently high so as to prevent total combustion of this component when burning at any season, but especially in fall or winter.
- Sufficiently large acreages should be burned in order to avoid overuse of regrowth vegetation by Park ungulates.
- Prescribed burning can be used to attract ungulates to key areas for convenient viewing by Park visitors. Nearly all the rangeland within the Park is in excellent range condition, and populations of native ungulates appear to be in balance with annual forage production. For these reasons no difficulty was anticipated in sampling forage yields. Furthermore, the burned area at each study site totaled less than 0.6 acre, while the total area burned was about 295 acres. Thus, it was postulated that if animals were attracted to the burned areas, subsequent grazing use of the study plots would be negligible since they comprised only a small percentage of the total area burned (less than 1%). Unfortunately this supposition was grossly incorrect and forage yields samples August 16, 1974 were greatly modified by utilization by bison and, to a lesser extent, by elk, antelope and deer.
- Spring burning, in particular, appeared to stimulate the production of western wheatgrass, the major component of most range sites. Burning at this season should be done before new growth is initiated in spring.
- Burning in fall or spring reduced the density and abundance of the annual grass, Japanese brome, thereby reducing the competition for soil moisture and nutrients with native vegetation.
- Burning in fall and winter may reduce soil moisture in spring, especially when winter and spring precipitation is below normal.
- Continuing studies are necessary to determine the frequency at which Park grasslands can be burned without diminishing their quality or productivity. These studies, of necessity long term, should monitor soil moisture, temperature, and chemical changes, vegetation composition changes with various burning frequencies, and density, height, and frequency of key plant species as an indictor of plant vigor.