Home on the Range for the blue oak

Issue Date: November 14, 2007

By Bob Johnson

Vance Russell, Audubon Society regional director, oversees several conservation projects at Bobcat Ranch near Winters, including helping blue oak seedlings grow to become mature trees.

As one approaches the 6,800-acre Bobcat Ranch from Winters, the hillside is well carpeted with trees, more than 90 percent of them blue oaks.

But the scene may be somewhat deceptive. The blue oaks may be plentiful on the ranch, but their age and size follow an unsettling pattern that has become familiar in many areas of the state. There is an abundance of older mature trees. And there are also many seedlings coming up beneath these majestic elders. But there are very few young trees that are heading toward maturity.

"The blue oaks out here look like they're about the same age," said Vance Russell, the Audubon Society regional director who oversees a number of conservation projects at Bobcat Ranch. "They're about the same size."

For many decades observers have been concerned that the failure of blue oak seedlings to grow into young trees could eventually lead to a decline of the blue oak trees that dot the California landscape from the Siskiyous to the Tehachapis.

A group of ranchers and researchers from throughout the state are working together to see if there are practical steps that could be taken on oak rangeland to help these seedlings grow to become mature trees.

University of California Cooperative Extension natural resources specialist Doug McCreary has designed a field trial of simple and economical steps ranchers can take to help the oaks on their grazing lands grow toward maturity.

At six ranch sites throughout the state, including the Bobcat Ranch in Winters, a few of the oak seedlings are being protected by plastic tubes. Other seedlings are being kept in the shade, shielded from effects of the harsh summer sun. Herbicides were used to clear the ground surrounding yet another group of seedlings, to give them a head start in the competition for nutrients and water.

Studies have already shown that management practices can help the seedlings survive. But these practices have been too expensive, too time-consuming or both for ranchers to implement.

The causes of the failure of blue oak seedlings to become blue oak sapling are complicated, and they vary from site to site.

"The reasons for poor regeneration of blue oaks vary by site and include competition from dense annual grasses, browsing by domestic livestock, and herbivory from a wide range of wildlife including grasshoppers, squirrels, gophers, voles, rabbits and deer," McCreary said.

The Audubon Society has already done four years of restoration work at the Bobcat Ranch in cooperation with the former landowner and with the rancher.

There are numerous attempts on the ranch to establish native perennial grasses as a way to crowd out noxious weeds. Cattle grazing has played an important role in these restoration efforts.

The first step is to burn one or two years in a row to kill weeds, then seed the perennial grasses in the fall. Herbicides are used to kill the broad leaf weeds.

Then the cattle take over. Because they tend to prefer the annual grasses, according to Russell, the trick is to pull them out a little sooner in the restoration plots.

"It's different with every field, but it's a matter of timing and the number of cattle," he said. "We've been pretty successful in getting the native grasses established and keeping the yellow star thistle and Medusa head out."

Russell said he thinks that a grazing program that works best for the young oaks can also eventually be worked out.

"One of the problems with blue oak research in the past is that it has looked at grazing in terms of either grazing or no grazing," he said. "It hasn't looked at the timing or intensity of the grazing."

Red Bluff rancher Arlo Strong, another cooperator in the trial, has seen cattle grazing and blue oak tree growth co-exist his entire life.

"We run cattle on it and grazing doesn't hurt the oaks a bit," said Strong, who grazes 75 cows and an additional 55 calves on the 500-acre Red Bluff ranch he was born on 82 years ago. "We've got almost nothing but oak trees out here. The trees don't bother the cows any."

The acorns can be a nuisance for the cows, but that problem is minor.

Strong manages the oak trees as another source of income from the ranch.

"We cut a lot of wood out of there; but when we cut we don't take everything," Strong said. "We take the wood to the city and sell it. It's another way of getting a little cash from the ranch."

Strong figures that there is 80 percent to 85 percent regrowth of the oaks that he does cut and he has not seen oak regeneration problems on his ranch.

He said he is taking a wait-and-see approach to the oak tree survival trial McCreary has set up on an area of his ranch.

"Doug's got trees all in a big tube," Strong said. "He says the trees will grow right out of the tubes, but I haven't seen it yet."

It will take years before this trial results in any meaningful information about what works, and what doesn't, in helping blue oaks regenerate on ranches.

When McCreary spoke about his trial in the spring, most of the ranchers in the group were supportive but one of them said it can be very difficult to find the protective tubes in relatively small quantities.

The Audubon Society purchases their plastic cylinders from Treessentials, a Minnesota-based company that offers protective cylinders of varying sizes. The Audubon Society purchases fairly large numbers of cylinders for many conservation projects and is able to get them for between $1.50 and $4 each, depending on the size.

"There are other things you can use like milk cartons, which are cheap or free," Russell says.

(Bob Johnson is a reporter in Magalia. He may be contacted at bjohn11135@aol.com.)

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item. Top