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Drought Puts Stress on Rare Torrey Pines

March 21, 1991|DIANE CALKINS

Although recent rain storms dampened the dusty trails within the Torrey Pines State Reserve, they arrived too late to save more than 350 precious trees.

More than four years of below-average rainfall has stressed the nation's rarest of pines, leaving the species vulnerable to the opportunistic bark beetle.

About 25 to 30 trees died during the first dry winter, according to Park Supervisor Bob Wohl. But, as the water table has dropped, the visual indications of stress have accelerated. As more trees become affected, the number of beetles increases.

Nearly 90% of the Parry Grove Trail is dead. One hundred more trees in the reserve are showing visible signs of deterioration.

"Healthy trees have defense mechanisms," said Chris Platis, a ranger at the reserve. "Without sufficient moisture, the trees don't produce sap which usually pushes out through pores. This allows the beetle to invade the cambium layer, the area of growth for the trees."

Park rangers and concerned volunteers have watched helplessly as the trees turned brown and died. Since the land is a reserve, the trees cannot be watered or sprayed artificially.

"There is also some talk of a possible prescribed burn to clear out dead trees and undergrowth," Platis says, emphasizing the preliminary nature of those discussions. "There are plenty of seeds on the ground from fallen cones, but the ground is not ready to accept the seeds. Preparing the ground correctly with fire could provide a tremendous opportunity for seedlings to survive."

Despite the recent losses and questions about how the trees will fare in additional years of drought, the torrey pine is well-established. More than 6,000 cling to the wind-swept landscape at the reserve.

It was Charles C. Parry, a botanist accompanying the United States and Mexican Boundary Survey, who first documented the stand of torrey pines in 1850 and gave the trees the name Pinus torreyana. He counted 200 specimens.

"A new species of pine is peculiar to the district," he reported. "It occupies an arid tract near the ocean beach, about 12 miles north of San Diego. In this locality . . . it forms a small sized tree, with rather open foliage. It is particularly distinguished by its long fascicles of leaves, which are in fives, and its large ponderous cones."

Torrey pines grow naturally in only two places in the world, in what is now the reserve and on Santa Rosa Island, located off the coast of Santa Barbara.

Their occurrence in this particular part of North County is probably the result of a specific micro climate, says R. Mitchel Beauchamp, author of "A Flora of San Diego County, California." An offshore expression of the Rose Canyon Fault cools the ocean water, thereby creating more fog than is found in surrounding areas. That fog and the usual seasonal rain provides moisture for the trees.

More than a century ago Parry warned that these rare trees would be exterminated unless someone stepped forward to watch over them. That someone turned out to be Ellen Browning Scripps of La Jolla, co-founder of the Scripps Institution of Oceanography, among other ventures.

She purchased several plots of land in the early 1900s, and later combined her holdings with city-owned land to form Torrey Pines Reserve. The reserve, which includes a lodge built by Scripps, opened to the public in 1923.

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