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New Mexico State University

New Mexico State University

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Gila Study Shows Grazing Light on Riparian Areas

LAS CRUCES - A New Mexico State University study about the impact of grazing cattle and other animals on some areas within the Gila National Forest indicates that the level of grazing is within U.S. Forest Service guidelines.

Earlier this year, Forest Service officials contracted with NMSU's Agricultural Experiment Station to examine possible damage done to grass and other plants in riparian areas, the land around streams and rivers, said Chris Allison, an NMSU range management specialist.

"The study's results show that area is not being overgrazed," Allison said. "The impact of grazing cattle, elk and other animals on the herbaceous vegetation in those areas falls within the Forest Service's use guidelines."

Specific plant life in the study that was not adversely affected by grazing animals included Kentucky bluegrass and willow and cottonwood trees, he said.

"The Forest Service set up a guideline of 40 percent utilization level of the major grass species in that area, meaning 40 percent of the plants could be used for grazing." Allison said. "Our research determined overall use in Black Canyon was between 40 and 50 percent of the herbaceous vegetation and 5 to 10 percent of the key browse species, such as willows and cottonwoods."

To measure the impact, the Forest Service and NMSU hired an independent range consultant to place cages around plants of upper Black Canyon, South Diamond Creek and Main Diamond Creek.

"Every three weeks, the consultant would return to the cages to determine how much forage was removed on the outside of that cage," Allison said. "At the end of the season, he clipped and weighed the grass that's inside the cage and compared that with what was outside to estimate the amount lost to cattle grazing, elk grazing, weather or other factors."

Another part of the study involved designating cross- sections of canyon areas to sample vegetation composition, the percentage of removed forage and the numbers of plants grazed.

The study's results may help provide information for future land use decisions. The land under study is part of the Diamond Bar Ranch, the largest allotment in the Forest Service's Southwest Region and an area that lies within the Aldo Leopold Wilderness Area. Concern over the preservation of riparian areas prompted the study.

"There's been a lot of concern from the Forest Service and a lot of the environmental groups that the area was not being managed correctly," he said. "Some groups have blamed cattle grazing for the loss of plant life in those areas, but you really can't tell which animal used the grass -- cattle or elk."