Thursday, April 16, 1998
When the earliest Spanish and European settlers first gazed upon the oak-studded hillsides and valleys of Central California, they encountered a wildly beautiful, fertile land that embodied their conception of the New World as paradise.
A little more than two centuries later, California''s Valley, Blue and Coast Live oaks remain a living link to the state''s cultural and natural history. But to gaze on the oak savannas and woodlands of Monterey County today is to see a landscape that is in fact, slowly and inexorably dying.
"The death spiral has really started and the prognosis is terrible," says Mark Stromberg, resident director of UC Berkeley''s Hastings Natural History Reserve in Carmel Valley. "Most of the oak trees are at the end of their life-cycle and what we are witnessing is a dramatic form of permanent de-forestation."
In much the same way that the first European settlers brought diseases to the New World that nearly wiped out California''s indigenous, Native American populations, they also brought with them plants, domesticated animals and farming practices that over the centuries have been slowly killing the Valley and Blue oaks of the Central Valley.
Where oak savannas once stretched over 400 miles from Los Angeles to the northern end of the Sacramento Valley, most have been forever lost from the conversion of the Central Valley''s wildlands into row crops and orchards.
Based on studies published by the Sacramento-based California Oak Foundation in Oaks of California, as much as 90 percent of Valley oak riparian forests were destroyed by the beginning of 20th century. Since the mid-1940s, more than 1.2 million acres of oak woodland habitat have been lost to urban development and agriculture. Between 1945 and 1975, 32,000 acres of oak woodland were cleared every year.
Approximately 14,000 acres are lost to residential development each year, and it is estimated that an additional 244,000 acres of Coast, Blue and Valley oak woodland will be lost early in the next century. Another 25 million acres, says the foundation, are at risk.
"The Central Valley had oak forests like parks with bear, elk and a diversity of wildlife," says Stromberg. "The oak acorn was the most important foodstuff for wildlife and Native Americans. But people came to California with the idea of throwing it away, to use up resources with no thought about the future."
Monterey County is home to all but two of the state''s eight dominant oaks. Ranging from the coastal peaks of the Santa Lucia Range to the woodlands, verdant hillsides and inland valleys of the county, it is the Coast Live, the Valley and the Blue oaks that dominate the local landscape. It is the Valley Oak in particular, rising hundreds of feet in cathedral-like, arboreal splendor, that are the most inspiring and most threatened of the native oaks. Here in Monterey County, continued population growth and the conversion of wildlands into vineyards is raising concerns over the accelerated loss of oak woodlands.
According to Stromberg, the oaks sustain well over 300 species of animal and plant life, and for centuries were a staple of Monterey County''s Native American populations.
It was the pioneering research by Hastings'' former director Jim Griffin back in the 1970s that provided the first comprehensive data showing that the Blue and Valley oaks here in Monterey County were not reproducing.
"In life insurance terms, the whole Valley oak community verges on disaster," is how ecologist Jim Griffin characterized the results of his research.
Stromberg says it is a combination of man-made and natural factors that account for the slow demise of the Valley and Blue oaks, and the story for the oaks here in Monterey County is the same story throughout the state.
"Many different animals feed on oak leaves and acorns, but the greatest impact is from animals that devour the seedlings and young saplings," says Stromberg, who notes that the Blue and Valley oaks are much more sensitive to browsing pressure than the Coast Live oak. Wild pigs have been hell on oaks, and cattle were the ''coup de grace.''"
Contributing to the loss of Valley oaks are a lack of predators to control deer and rodent populations, and the reduction in natural fire controls that help clear the understory of grasses and plants that choke out oak seedlings.
"Oaks are limited by a complex interaction of grasses, and animals eating oaks as seedlings," says Stromberg. "The problems oaks have in reproducing need to be looked at in terms of all the things that control reproduction."
One problem oaks can encounter early in their reproduction cycle, says Stromberg, are wet springs that can prevent the oak flowers from pollinating.
"Research has shown that during wet springs, when oak flowers are out, the pollen is rinsed to ground," explains Stromberg. "Some oaks can take up to three years to go from flower to acorn, and long before the acorns fall from the tree they are removed by animals like woodpeckers, scrub jays and squirrels."
Just how unique and dependent oaks are on wildlife for reproductive success is highlighted by the interaction between Valley oaks and the scrub jay.
"Scrub jays are the biggest disburser of acorns and critical to tree survivorship," says Stromberg. "A single scrub jay can plant up to 10,000 acorns in a season."
Despite the assistance of scrub jays in re-seeding acorns, the competition for soil and moisture is a challenge few oaks seem able to overcome.
"Blue and Valley oaks as they come up, typically grow in a matrix of European weedy grasses," explains Stromberg. "Ninety-five percent of the grasses we now see are barnyard grasses from Spain that flower at the same time the acorn is trying to sprout. They extract more soil moisture than the native grasses and 80 percent of the acorns die."
In addition to the competition for soil and water, the non-native grasses attract gophers, which Stromberg says eat oak seedlings and turn over half the soil surface, further preventing acorn germination.
"If you could exclude gophers, 100 percent of the oaks could live, but if the gopher is present, 100 percent will die."
Of particular concern to Stromberg is the conversion of additional Salinas Valley farmland to vineyards, which results in additional losses of oaks.
"Agriculture is the number-one culprit," says Stromberg. "We are removing habitat for wildlife. A whole biodiversity of 300 species goes on underneath the oaks that is being eliminated. We''ve got to manage and protect old trees while adding and managing young trees. Without management, we won''t have any more oak woodlands."
The future viability of the Valley and Blue oaks will depend in part, says Stromberg, on individuals helping to restore the oaks by planting acorns and nurturing young oak seedlings.
At Hastings, numerous plastic tubes containing acorns and oak seedlings are scattered throughout the reserve in an effort to help re-seed the oaks.
These "tree tubes," as Stromberg calls them, contain single acorns that have been planted by hand in the tubes, surrounded by mesh wire to protect the roots, and covered with more wiring to prevent grazing of the young shoots. According to Stromberg, individual land owners can help restore the oaks by planting similar tree tubes on their property.
On the public front, the Oak Foundation is working to save the remaining stands of Valley oaks through public education, political lobbying, and through the acquisition of conservation easements on privately owned land.
According to Executive Officer Janet Cobb, the Oak Foundation is negotiating to purchase its first conservation easement for an 18,000 acre ranch in the southeastern portion of Monterey County. In addition, the Oak Foundation is working to have the Valley oaks listed as a threatened species at both the state and federal levels.
"We lost 95 percent of our wetlands from greed and ignorance, and we''re asking the governor, the board and forestry, state [Department of] Fish and Game, and elected officials to take a hard look at the oaks," says Cobb.
"We have no intention to let the oak woodlands go the same way as wetlands."
Of California''s 100 million acres, about 10 million are oak woodland and another 20 million mixed hardwood and oak woodland. With approximately 85 percent of oak woodlands owned by private landowners, Cobb says the future survival of oaks will ultimately depend on public ownership of conservation easements.
"If we want this land for habitat, watersheds and clean air, then we have to be willing to buy easements to let families stay on their ranches and manage their land," says Cobb. "By and large, landowners are doing a good job and we''re looking forward to working with them."
From Cobb''s perspective, saving California''s oaks is as much about saving the state''s history as it is preserving the land itself.
"There is something about a 400-year old trees that gives us a sense of time," says Cobb. "In California, we don''t have much of a sense of history. The oak for California is a cultural tie to our past and future."