The following analysis of the relationships between fire suppression, removal of predators, overbrowsing by deer, the permanent loss of aspen forest and the associated loss of many other plant species, appears in a 1960 doctoral dissertation by botanist Hayle Buchanan, an expert in the plant biology of the high plateaus of southern Utah.
(Emphasis added below in boldface.)
"In May, 1956 C.M. Aldous, National park Service Biologist, visited BCNP to ascertain the extent of build-up of the population of deer and its effects upon the browse plants. He reported serious damage from over-browsing to bitterbrush, horse brush, curl leaf mahogany, birchleaf mahogany, elderberry and aspen. He stated that for the limited amount of available browse and the drought conditions that there were too many deer present for the plants to maintain vigorous growth. He recommended that the state be encouraged to make it possible for heavy removals of deer in the areas adjacent to the park during the deer-hunting season of 1956. He further recommended that NPS personnel be authorized to make the necessary deer reduction within the park before the deer-hunting season of 1957 if his first recommendation proved to be unsuccessful in reducing the deer population. He suggested deer counts to determine trends of deer population. The counts were to be made twice each month, early in the evening, along a fifteen mile drive through the park from a car traveling at a speed of 15 miles per hour... Records of deer seen were to be recorded."
"In accordance with Mr. Aldous's first recommendation, the NPS tried to persuade the Utah State Dept. of Fish and Game to issue special permits to take extra deer from the area adjacent to BCNP during the 1956 deer hunting season. The game warden from the Panguitch district refused to administer a special hunting season. Mr. Aldous' second recommendation was not carried out. Some deer counts were made from 1956 to 1959 according to Mr. Aldous' suggestion, but not consistently enough to give a complete picture of deer population trends. The data of deer counts indicated, however, that the population of deer is increasing, especially during the autumn season."
"In July 1957 a one-acre study plot on Whiteman Bench was enclosed by a nine-foot fence to determine the recovery of deer-browse plants. The Utah State Fish & Game Commission and the NPS collaborated in the study. The deer exclosure included most of the shrubs which were being used by the deer. Shrubs inside and outside of the deer exclosure were marked with pegs and numbered with metal tags. Measurements were taken of the size of these woody shrubs along with notes as to browse utilization. Some of the shrubs were photographed. These records were to be compared with similar later measurements, notes and photographs to determine the effect of deer populations on browse plants."
(pp. 119-120)
"One of the most urgent ecological problems within BCNP concerns the overpopulation of mule deer. The primary cause of the increase of mule deer was the destruction of many of their natural predators. At the present time the NPS offers protection to predators as well as to other animals, but prior to 1931, predator destruction occurred in areas under NPS administration, as described by Cahalane (1939). BCNP, however, is much too small in size to provide most predators of mule deer within a home range. The Paunsagunt Plateau is part of a relatively small summer range located in proximity to an extensive area suitable for winter range of mule deer. Seasonal migrations of deer occur into and out of the park to meet their needs for food and suitable climatic conditions. Hunting pressure in areas adjacent to the park has not been sufficient to reduce the population of mule deer below the carrying capacity of the summer range. Consequently, the population of mule deer has steadily increased. The seriously overbrowsed shrubs and trees within the park has brought forth recommendations from biologists for extra hunting periods in areas adjacent to the park, and for shooting of mule deer by personnel of the NPS. The first recommendation was put into effect in 1958 and 1959, but has been unsuccessful in reducing appreciably the population of mule deer."
"According to observations during the summers of 1957, 1958, and 1959, the damage to many species of browse plants is extensive. The species of shrubs and trees most in danger include: bitterbrush, mountain lilac, mountain lover, snowberry, Gambel's oak, elderberry, curlleaf mahogany, waxleaf currant, and especially, aspen."
"The condition of aspen at BCNP justifies special attention. The contribution of this species of tree to the aesthetic value of the higher forests of the park is immeasurable. Cottam (1954) has discussed the nature and value of this tree in the forests. Unlike all other predominant forest species with which it is associated, the aspen is deciduous. Aspen stands are usually sharply discontinuous, single-aged, and usually dense..."
"Aspen trees in this region have not reproduced by seed for perhaps 8,000 years. Reproduction is vegetative, from underground root systems. Ordinarily all of the aspen in a stand belong to the same clone, but occasionally genetically separate clones merge. Most aspen trees have a relatively short life span, which averages less than one hundred years. Maintenance of aspen in an area requires continued growth of aspen suckers from the clonal root system. The mule deer at BCNP have kept the aspen suckers constantly browsed off for many years. Throughout the present intensive study of the park, practically no aspen suckers were found. Furthermore, abundant evidence was found of aspen saplings and young trees which had been killed or weakened by the overbrowsing of mule deer. In certain areas of the park, aspen stands have died out completely within the thirty-two year period of management by the NPS. Unless effective methods of reducing the deer population are taken immediately, the beautiful aspen groves of BCNP will be a historical item for the park visitor of the next generation. To allow the aspen to disappear from this national park is certainly not 'conserving the scenery and natural ... objects ... unimpaired for the enjoyment of future generations', as specified in the Organic Act of 1916."
"The striking recovery of many of the species of shrubs from overbrowsing within a one-acre deer exclosure during the two-year period, 1957-1959, indicates that the extent of damage presently being done by mule-deer is great. Unfortunately, the one-acre exclosure contained no aspen trees. A similar one should be constructed in a stand of aspen. Many of the browse plants inside the exclosure have increased vigor, especially tagged shrubs of bitterbrush. Some effective method of reducing the population of mule deer should be taken and continuous efforts should be made at all times to maintain the population of mule deer within the limits of the carrying capacity of the summer range."
(pp. 134-125)
From: Buchanan, Hayle, 1960, The Plant Ecology of Bryce Canyon National Park. Doctoral thesis, University of Utah Department of Botony, Salt Lake City, Utah.