The condition of browse plants at the Theodore Roosevelt Memorial Ranch (TRMR)

Abstract

The Theodore Roosevelt Memorial Ranch (TRM), owned and operated by the Boone and Crockett Club, spans 6,000 acres along the Rocky Mountain East Front. The ranch is located west of Dupuyer, Montana, on the forks of Dupuyer and Scoffin Creeks. Each fall, mule deer migrate from the Bob Marshall Wilderness and adjacent Lewis and Clark and Flathead National Forests to the ranch and adjacent private lands. Winter counts and classifications have been conducted since the mid-1970’s by Montana Fish, Wildlife & Parks personnel. In addition to mule deer, domestic livestock, whitetailed deer and elk compete for space and forage on the winter range. Browse species such as chokecherry, aspen, serviceberry, red osier dogwood, horizontal juniper, and willows are utilized by all ungulates in the area. The Dupuyer Creek winter range shows evidence of severe over-browsing on these species. Coincidentally, mule deer and elk populations have historically been higher here than other areas along the mountain front. Over the past 22 years, mule deer densities have been calculated at over 75 deer per square mile over the entire winter range and up to 200 per square mile on the TRM itself. Winter ranges are occupied from mid-November through May. Winter counts are conducted in January and again in March to assess fawn and adult survival. An average of 2,100 mule deer are surveyed annually, with fawn/doe ratios of 71, fawn/adult ratios of 54, and buck/does ratios of 33 (ratios are expressed as animals per 100 does or adults). Mule deer migrate back to higher elevation summer ranges in mid- to late-May, traveling as far north as Glacier National Park and westward to the South Fork of the Flathead River. Less than 15 percent of the wintering population remains along the mountain front during the summer. Movements back to winter range may occur in early October, with the majority of animals present by November 15th. As background for a more comprehensive study, we collected data in September and October 1999 from which to assess the impact of ungulates on browse plants. There were three general objectives: 1) determine the current level of browsing intensity, 2) reconstruct histories of browsing, and 3) determine the effect of browsing on rate of stem growth.