Final Report for FW95-017
This study sought to assess the levels of forage utilization by Rocky Mountain elk on the mountain meadows found within the 92,000-acre Glenn Allotment on the Gila National Forest in southwestern New Mexico. The researchers hoped to add to the body of knowledge to help range and forest managers in their pursuit of effective multiple-use management of the public lands for wildlife, livestock and other uses.
Rocky Mountain elk, released into New Mexico’s Gila National Forest in 1927, have increased in number to the level that they are causing conflict relative to multiple use management and habitat sustainability, especially regarding forage for livestock and wildlife. Some ranchers argue the steady increase has limited their livestock numbers below stocking rates allocated by the USDA Forest Service. Even with low livestock densities, high elk concentrations can cause overgrazing. Sometimes the overgrazing occurs only in the spring. Other times it’s year round, notably in riparian areas, where the Forest Service typically allows producers to use 35 to 45% of vegetation.
Mountain meadows tend to produce higher levels of quality forage than the surrounding forest, making them ecologically significant and attractive to wildlife. However, recent studies suggest these meadows are shrinking from forest encroachment. Because of the meadows’ importance, the SARE-funded researchers selected for study and monitored seven meadows not grazed by domestic livestock to assess the impact of elk. The goal is to help natural resource managers improve management practices for elk in the Gila National Forest located in southwestern New Mexico. The forest occupies about 3.3 million acres of publicly owned forest and rangeland intermixed with small amounts of private land. Elevations vary from 4,500 to 11,000 feet, and annual precipitation ranges from 12 to 28 inches. Drought is common and vegetation is often water-stressed in early spring and fall.
In each study site, the SARE researchers set up 4-foot by 4-foot exclosures in 1996 then compared grass clipped inside and outside the cages, before and after the growing seasons, in 1997, 1998 and 1999.
The vegetation use rates varied among the seven mountain meadows and within each, making broad generalizations difficult. However, the results suggest that the elk ate more of the vegetation during the dormant season from October to May (43.4%) than during the growing season from June to September (39.8%). The lower use during the growing season may be explained by more abundant forage and greater dispersal of elk. Also, during years of normal or above-average precipitation, adequate upland forage may relieve pressure on the meadows.
The researchers found that the elk used more vegetation on the mesic areas (48.0%) than on the xeric areas (35.2%), a difference explained by the greater desirability of succulent, palatable plants, especially when precipitation is low. That may be the same reason that during the dormant season the elk consumed more vegetation in the mesic areas (56%) than in the xeric areas (30.8%). During the growing season, the elk consumed about the same amount of vegetation in the mesic sites (40.0%) and in the xeric sites (39.7%), a similarity explained by greater elk distribution.
Despite considerable variability in use between meadows, the average utilization over the three-year study and across mesic and xeric areas within mountain meadow sites fell below the 50% standard utilization for the Gila National Forest.
The study suggests that along with appropriate elk-harvest levels, management practices that include tree and shrub thinning, prescribed fire and fertilization may help influence the dispersal of elk away from mountain meadows by enticing them into adjacent uplands.
FARMER ADOPTION AND DIRECT IMPACT
As previously stated, this and future studies are needed to help range managers and ranchers understand the impact of elk on forest rangelands and meadows and how to best manage wildlife and livestock for multiple use.
FUTURE RECOMMENDATIONS OR NEW HYPOTHESES
Mountain meadows are important foraging areas for elk. But to further assess the impacts elk are having on the mountain meadows of the Glenn Allotment, changes in species composition need to be monitored.
DISSEMINATION OF FINDINGS
The information has been disseminated to members of the Gila Permittees Association.
The Gila Permittees Association played an integral role in securing the funding for the project, which would not have been possible without the guidance and assistance of Becky and David Campbell from the Gila Hotsprings Ranch.