Abstract - Effects of Fire on Forest Floor Vegetation in Ponderosa Pine Forests in the Southern Black Hills
Bock, Jane H. and Bock, Carl E. 1980. The Effects of Fire on Forest Floor Vegetation in Ponderosa Pine Forests in the Southern Black Hills. First of Three Reports: Final Report on CX-1200-9-BO34 for Spring 1979 to Spring, 1980.
The purpose of this study is to determine the effects of prescribed burning on understory vegetation in the coniferous forests of the southern Black Hills. The overstory is comprised primarily of ponderosa pine, but certain deciduous hardwoods make a small contribution to the forest canopy of the region, especially in more mesic sites. For example, American elm (Ulmus americana L.) now in decline due to Dutch elm disease, burr oak (Quercus macrocarpa Michx.), paper birch (Betula papyrifera Marsh.) and aspen (Populus tremuloides Michx.) may well fill this role. The understory vegetation is comprised of several shrub and sub-shrub species. Notable among these are serviceberry Amelanchier alnifolia (Nutt.) Nutt, mountain mahogany (Cercocarpus montanus Raf.), chokecherry (Prunus virginiana L.), wild rose (Rosa spp.), lead plant (Amorpha canescens Pursh), snowberry (Symphoricarpos occidentalis Hook.), currants (Ribes spp.), skunk bush (Rhus trilobata Nutt.) poison ivy (Toxicodendron rydbergii) (Small ex Rydb. Greene), strawberry (Fragaria virginiana Duchesne), and red raspberry (Rhus idaeus L.). These species fill several ecological roles. First, they are primary producers. Second, they furnish shelter and resting places for several species of animals. Third, they are important sources of food for many species of big game. For example, elk, deer and antelope, are known to use some or all of these shrub species. This is documented by the general literature of wildlife biology and by numerous studies carried out at Wind Cave National Park. Also, song birds and other birds feed upon fruits and insects found on the shrubs. Fires have been a part of the Black Hils' ecosystems throughout the modern geologic period. Although his implied view of the Indians' perception of fire and his view of post-fire succession is erroneous, Donaldson's (Krause and Olsen 1974, p. 60) general description of fire's occurrance (in 1874) is an accurate one. "But as might be expected, the Indian has not been more fortunate than the white man in saving forests from destruction. Thousands of square miles have been burned over, giving to burnt districts a sort of desolate and graveyard look. In some cases a new growth has sprung up; but a burned pine forest seldom reproduces itself." Although these woody plants along with fires have prime ecological importance to the ecosystems of the southern Black Hills, to our knowledge only one major study (Gartner and Thompson, 1972) has been done in which the shrub layer and its relationship to fire is mentioned. This may be due, in part, to the fact that is is self-evident to observant people that fire often enhances shrub growth in the Black Hills. On the Custer expedition the expedition botanist, Professor A.B. Donaldson, in 1874 (Krause and Olsen, 1974, p. 64) reported "... But of raspberries there was no end. Acres and acres of the mountains' sides were covered with them. They literally reddened the ground. They were large and sweet and could be picked in clusters from three to six. The bushes were not large, but they were loaded with the lucious fruit. They grow best where the forests had been burned and were found all the way to the top of Harney's Peak." In our first year's work we established study plots, censused vegetation on sites chosen for control burning, and on one five-year-old burn, and on control sites which remained unburned.