HELPING THE ‘ECOSYSTEM ENGINEERS’
Volunteers lend a hand to re-establish beaver dams on the Rio Cebolla
NORTH OF JEMEZ SPRINGS — “It looks like a beaver has already been here,” Cecil Rich said enthusiastically after spotting the short stump of a what used to be a tree about 5 inches in diameter.
A fish and aquatic biologist with the U.S. Forest Service, he gestured with two thumbs up toward a couple of colleagues over the find.
On the other side of the Rio Cebolla, a stream only about 5 feet wide here where it runs through a meadow in the Jemez Mountains not far from the San Antonio campground, there was more evidence. The stub of a willow sprout that had just been planted a few weeks earlier had the tell-tale signs of teeth marks where it had been chopped off.
“At least they didn’t chop them all down,” Rich said, then quipped, “They don’t need to be such eager beavers.”
About a dozen volunteers and Forest Service employees had been as busy as
the semi-aquatic rodents one morning last week building 10 beaver dam analogs as part of the Southwest Jemez Mountains Landscape Restoration Project.
While this method of utilizing human-made dams to alter the landscape has been employed elsewhere, it’s the first time it’s been tried in New Mexico.
The wide-ranging restoration project that also involves prescribed burns and forest thinning is an effort to develop sustainable ecological forest conditions on more than 200,000 acres on the Jemez River watershed, including parts of the Valles Caldera National Preserve, Santa Fe National Forest and Jemez Pueblo tribal land.
Building the dams along this stretch of the Rio Cebolla is an effort to improve the habitat for fish and wildlife, including the New Mexico meadow jumping mouse, which was designated an endangered species by the U.S. Fish and Wildlife Service in 2014.
In fact, barbed-wire fencing surrounding the meadow where the dams are being built was erected four years ago so to protect the mouse habitat from the damaging effects caused by grazing cattle and, potentially, people.
While the ultimate goal is for the human-made dams to disperse water from the stream across the flood plain to improve the habitat, getting the beavers to come back would be a sign of success.
“Historically, this was an old beaver meadow before they got trapped out in the 1800s,” Rich explained, and the tree stump left by the beaver was a good sign. “That tells you they’re around. They’re looking for sources of food.”
Rich says beavers are a keystone species, meaning their presence creates conditions that allow other animals and plants to thrive. He calls them “ecosystem engineers.”
“They change the habitat to meet their own needs,” he said. “It’s amazing they can have such an effect on their environment. And they work cheap.”
So do the volunteers that have been helping with the dam-building project. Rich says that groups like Defenders of Wildlife, New Mexico Trout, Trout Unlimited and others have been a huge help, participating in work days like the one Thursday.
Art Vollmer, a member of Trout Unlimited’s Truchas chapter and also chair of the group’s state council, helped build eight beaver dam analogs a little farther downstream last October and was helping out again last week.
“They do all the hard work, moving the rock and the willows,” Vollmer said of the Forest Service. “It makes it so much easier when the materials are in place.”
The Forest Service also prepped the project by using a hydraulic post pounder to erect a dozen or so posts across the stream at the location of each dam. The workers used rock to stabilize the bottom of the channel, weaved the willows between the posts and pushed them down the best they could. The brown trout, Rio Grande chub and Rio Grande suckers that swim the stream can still get through.
It took about an hour for each crew of three or four people to build each dam. Not only do they disperse the water onto the meadow, but also the dams work to capture sediment and keep it from flowing downstream, thus purifying the water that filters through.
Willows, like the one a beaver apparently got to, are planted along the side of the stream to stabilize the banks and reduce erosion. They also serve as food and building materials for the beavers that the crews hope will show up to build on top of what the humans did as they engineer the ecosystem.
In all, the Forest Service plans to build about 35 such dams.
“Time will tell if we know what we’re doing,” said Victor Kovach, another Trout Unlimited volunteer.
It didn’t take long to see results as, within minutes, water started backing up behind the dams.
Eventually, fishing on the Rio Cebolla will improve, but that’s not the only reason Trout Unlimited is involved.
“We’re predominantly a cold-water conservation organization,” Vollmer said. “We believe a healthy watershed will lead to a healthier stream and that leads to healthier fish and better fishing. You can’t have one without the other.”