Purshia: The Wild And Bitter Roses

Notes

222 Purshia of such organizations as The Nature Conservancy throughout the West. One frequent problem with this type of acquisition is that funds for managing the acquired resource are often not included. When working ranches are acquired for mule deer habitat and the farming operations are stopped, the result is not always beneficial for the deer. Managers often hear that “the mule deer were better off while the ranch was still being farmed.” Two aspects of this type of habitat management are appropriate to our discussion. First, if some form of restoration of browse resources is not practiced on such damaged habitats, any positive influence on mule deer populations will be a long time coming. In fact, the preservation will be likely to have negative influences on mule deer habitat through such mechanisms as increased herbaceous fuel loads in browse stands. Second, the failure of deer to thrive on working ranches converted to game preserves illustrates how dependent mule deer populations in areas with degraded browse resources have become on agricultural crops, especially alfalfa (Fig. 12.5). Few big game managers advocate hay farming to support mule deer populations, but the importance of agricultural crops in meeting the nutritional requirements of mule deer needs to be considered when habitat preserves are established. Topping was once proposed as a management treatment to increase the browse productivity of overmature antelope bitterbrush plants. Ferguson and Basile first proposed this treatment in Idaho in the 1960s and then later tested it at several locations, including the Modoc National Forest in northeastern California.29 Overmature antelope bitterbrush plants from 5 to 7 feet tall were cut off 3– 4 feet above the ground. The purpose was to increase twig production on the limbs remaining below the cut. Before the cutting, many of the twigs produced on the limbs above the cut height were unreachable by mule deer. Topping initially stimulated twig production at all locations where it was tested, although the results were quite variable (Table 12.1). Within four years of the topping, however, production was not significantly different from the control plants. This type of labor-intensive treatment is very expensive (in the 1960s, $10 –35 per acre). The growth response to cutting is apparently mediated by a hormone, but it seems that no one has ever tried to enhance twig production of antelope bitterbrush plants by topical applications of plant growth regulators. That also, however, would be an expensive and labor-intensive treatment. Perhaps the most difficult issue in the management of Purshia stands involves the question of why so many antelope bitterbrush stands established 80 –100 years ago (in the early 1900s) are currently experiencing inadequate seedling recruitment. At that time the western ranges were excessively overgrazed , but these overgrazed ranges also experienced unprecedented events. Purshia Management 223 Fig. 12.5. Mule deer depredation of agricultural fields can be heavy, as shown here at the Buffalo Meadows ranch in northwestern Nevada. The hard winter of 1889–1890, for instance, reduced livestock numbers by almost 90 percent in northern Nevada,30 and ungulate wildlife populations were also very low as a result of promiscuous hunting. It is very difficult, and perhaps impossible, to make absolute cause-and-effect statements as to why bitterbrush stands became established at the turn of the century but are now experiencing difficulties in recruitment. Perhaps the low number of ungulate grazers immediately following the 1889–1890 winter favored the establishment of bitterbrush. Other factors working in favor of establishment in 1890 –1910 include (1) reduced competi- 224 Purshia table 12.1. Mean Twig Growth of Topped and Untopped Bitterbrush Plants over Four Growing Seasons Topped Control Location Year (inches) (inches) Boise, Idaho 1966 389* 175 1967 358 155 1968 186 111 1969 166 145 Sawtooth, Idaho 1966 296* 148 1967 187* 145 1968 195* 132 1969 188 112 Modoc, Calif. 1966 541* 225 1967 768* 332 1968 183 120 1969 239 145 *Asterisk denotes production significantly different from the control. Adapted from R. B. Ferguson, “Bitterbrush Topping: Shrub Response and Cost Factors” (Res. Paper 125, usda, Forest Service, Ogden, Utah, 1972). tion from perennial grasses because of extreme overgrazing, (2) reduced wild- fires due to lack of herbaceous fuel, (3) promiscuous fall burning by stockmen, and (4) lack of exotic annual grasses such as cheatgrass, which had not yet been introduced. Many photos of western rangelands taken...