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Study hints thinning junipers restores natural water flow
OSU scientists study junipers' effect on two watersheds
By Kate Ramsayer / The Bulletin
Published: July 01. 2006 4:00AM PST| order photo
John Buckhouse, an Oregon State University professor of rangeland ecology and management, fills his water bottle from a spring in the Mays watershed near Brothers, where researchers predict that cutting junipers will increase the amount of water in the ground and in springs.
Andy TullisThe Bulletin
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BROTHERS - Junipers fill a remote, dry valley on the east side of a High Desert ridge near Brothers, stretching as high as 50 feet in the air and sometimes growing so thick that their flaky branches touch.
But on the west side of the ridge, next to nothing is standing. Acres of trees are cut, lying on the ground with their drying needles turning brown.
"Oh I like this, that's the way it's supposed to look," exclaimed Prineville rancher Lynne Breese, catching her first glimpse of the western watershed. "It's wonderful."
The two neighboring watersheds, each about 300 acres, are an outdoor laboratory for a team of Oregon State University scientists studying how the trees affect the High Desert's water system.
The researchers first spent more than a decade measuring and observing the movement of water in the two unaltered watersheds, which are on private and Bureau of Land Management land. Last fall, they cut down a majority of the junipers growing in one of the watersheds. In the years to come, they’ll compare the two areas to investigate how juniper removal transforms landscapes.
Breese knows what happened on her family’s land. Her husband’s grandmother kept a garden fed by groundwater on the Prineville ranch.
“But as the juniper came in, it utilized the water,” Breese said. “The well went dry. Groundwater couldn’t flow.”
After she and her husband started cutting the junipers on their ranch in 1987, moisture returned to the soil and a creek started flowing again, she said. So now, they keep cutting the trees.
While researchers have heard many stories similar to Breese’s, this OSU watershed project is the first large-scale experiment to tackle the question scientifically, said project leader John Buckhouse, a professor of rangeland ecology and management at OSU.
“All the work up to this point has been on a fairly small-plot kind of a basis. This is on a watershed scale,” Buckhouse said this week during a tour of the watersheds.
Buckhouse and other researchers predict that getting rid of the junipers could promote the growth of grasses and shrubs. This could reduce soil erosion and result in more water seeping through the soil and sticking around later into the year. More water in the ground could mean more food and habitat for wildlife, more forage for livestock and more stream flow.
The project “has everyone in the West’s eyes on it, because how this turns out is going to probably have some very serious implications for how land is managed across the Intermountain West,” Buckhouse said.
An unprecedented abundance
Western junipers are native to the High Desert, but prior to the late 1800s only an occasional tree dotted the landscape, said Rick Miller, an OSU professor who studies junipers.
The trees can live to be more than 1,000 years old. They start off life slowly, spending the first 20 years putting energy into their root systems, before undergoing a growth spurt between ages 45 and 80 or 90, Miller said. He has sampled a tree that started growing in 100 B.C. and died about 400 years ago.
Juniper trees have been in Oregon for between the last 4,000 to 6,000 years, he said, “but it’s just filling in because of changes in land use ... We don’t think it’s ever reached the abundance it is today, it really is an unprecedented change.”
The change in Central Oregon began in the 1880s, when cattle and sheep ranchers began grazing huge numbers of livestock on the land, he said. Grazing fireproofed the landscape by removing the grasses and brush that fuel periodic fires, and the junipers proliferated without burns to keep them in check. This effect was amplified after World War II, Miller said, when firefighters ramped up fire suppression efforts in the region.
There were about 450,000 acres of western juniper in Oregon in the mid-1930s, but the trees now cover 6 million acres, said Tim Deboodt, an OSU extension agent in Crook County and co-leader of the watershed study.
And junipers use up a lot of water. On a warm day, a 12-inch diameter tree can suck up 50 gallons of water, Deboodt said. If there are nine to 15 trees of that size on an acre of land that gets 12 inches of precipitation a year, they could use all of it, he said.
“Much of Central Oregon is in a 12-inch or less precip(itation) zone. And much of Central Oregon has a higher tree density than that,” Deboodt said.
Scientists have seen shrubs and grasses thrive when junipers are removed from a landscape, Deboodt said. These plants slow water runoff, preventing erosion and allowing more water to seep into the soil. They also provide habitat for animals such as sage grouse.
But there weren’t any large-scale studies examining what happens to water because of the cost and difficulty of finding a site to investigate such a complex question.
Two watersheds
In the spring of 1993, rancher Doc Hatfield contacted Deboodt and others to look at two watersheds, Jensen and Mays, about a dozen miles north of Brothers. Researchers came out to see water flowing out of drainages in the Jensen and Mays watersheds, where Hatfield hadn’t seen it before.
Later that spring, Hatfield called again. At that point, those two watersheds were bone dry, Deboodt recalled, but a third one nearby called Holland Gulch had running water. The only difference appeared to be that Holland Gulch was clear of junipers, while Mays and Jensen were thick with them.
“The conversation began, maybe it’s a vegetation issue,” Deboodt said. “We speculated a lot but really didn’t know because there wasn’t any data.”
But then, OSU researchers started to collect that data in the Mays and Jensen watersheds with funding from the Environmental Protection Agency.
Michael Fisher was part of the team of researchers and studied the Jensen and Mays watersheds for his graduate work at OSU. In 1994, he started measuring soil erosion and studying the geology of the channel bottom. Then he put in a device to measure the small amounts of water coming down the watersheds.
Fisher, now an instructor with the forestry program at Central Oregon Community College, and Deboodt, who joined the watershed project in 2000, drilled wells to measure the amount and timing of groundwater flowing through the site. They also recorded soil moisture and temperature and conducted vegetation surveys.
“We’ve tried to look at all the different ways that water might express itself in each of these watersheds, both before and after treatments,” Deboodt said.
Cutting the trees
In October 2005, after researchers had gathered 11 years worth of data, contractors cut about 80 percent of the junipers on 280 acres of the Mays watershed.
“The goal was to cut everything, except the old growth,” said Deboodt.
Earlier this summer, project organizers worked with the Juniper Work Group to sell about 60 acres of the cut juniper for log homes and other uses.
Now, the focus will shift to looking for and analyzing differences in the newly juniper-free Mays watershed.
On a recent field trip, which drew about 30 people from OSU and other institutions and agencies, Deboodt reviewed some preliminary observations.
A spring in the treeless Mays watershed seems to be behaving differently from a spring in Jensen, he said. Jensen’s spring has slowed, while the Mays spring is “kind of holding its own,” he noted.
Measurements from wells in the Mays watershed showed a different pattern as well. In the two years prior to the juniper harvest, there was a sharp peak in water flow in the spring, followed by a drop off.
“This year it kind of climbed and now it’s sort of slowly working its way down,” Deboodt said.
He and others with the project will continue monitoring and studying the watersheds for at least eight years.
“I think it’s great that people are willing to do this sort of side-by-side comparison,” said Bill Marlett, executive director of the Oregon Natural Desert Association, a Bend-based environmental group. But he added that grazing probably has as much of an impact on the water system as junipers.
“It would be nice if they could move all the cows off both watersheds so that there’s just one variable,” Marlett said.
Having more water in the ground would benefit both wildlife and livestock, said Hatfield, the rancher.
“Basically, if we can get the water in the ground where it falls and hold it there as long as possible, then it benefits everything,” he said. “It lengthens stream flows and makes more diversity for wildlife, more livestock feed. It all fits together.”
The BLM has heard from a variety of people who have stories like Breese’s, said the agency’s John Swanson, who has been working on the watershed project. But this adds a scientific approach.
“By having new research and new information, that can help us prioritize which watersheds to do juniper treatments in,” Swanson said.
If a watershed empties into a fish-bearing stream, for example, juniper treatments could result in more flow and better fish habitat.
But first, the scientists have to gather and analyze the data, both from the control watershed with junipers and the experimental, juniper-free watershed. From there, they can start to tease out the effects of these prevalent trees on the High Desert.
“We have the before data for this and we’ll have the after data,” said Fisher. “And that’s pretty cool stuff.”
Kate Ramsayer can be reached at 617-7811 or at
kramsayer@bendbulletin.com.
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