Study Calls for Restrictions to Save the Sierra

The most comprehensive study ever made of the Sierra Nevada region on Friday recommended creating a system of forest reserves, restricting population growth and imposing stricter air quality controls to combat environmental threats degrading the range’s natural splendor.

Three years in the making, the Sierra Nevada Ecosystem Project found that nearly one-fifth of Sierra land animals are in decline, two-thirds of stream systems are degraded and almost 90% of the oldest, largest trees are gone from the national forests.

The $6.5-million study was done in response to a request by Congress for a report on the Sierra Nevada ecosystem by an independent panel of scientists. It reflects the views of more than 100 scientists whose work was overseen by a steering committee drawn from the U.S. Forest Service, the National Park Service, the Department of the Interior, the University of California, the California Academy of Sciences and the National Academy of Sciences.

The study measures the cumulative environmental effects of historical human activity, such as mining, logging, livestock grazing and exporting water, along with contemporary pressures from population growth, recreation and airborne pollution. It catalogs species already gone from the Sierra, including the California condor, the grizzly bear and Bell’s vireo and lists dozens that are in danger of disappearing, including bighorn mountain sheep and several types of frogs and birds.

At the same time, the report emphasizes that the Sierra’s natural wealth is by no means exhausted. Despite the losses, the study maintains, the Sierra remains rich in plant and animal diversity with more than 3,500 native species of plants and 400 species of mammals, birds, reptiles and amphibians.

While exposure to airborne urban pollutants is causing serious damage to trees and plants on the Sierra’s west slope, the study notes that elsewhere, to the north, “air quality is some of the cleanest in the nation and even the world.”

Overall, the tone of the study is guardedly optimistic: “Options exist now for charting the course toward restoration. Failure to use these options increases the chances of irreversible loss.”

It also points out that during the 150-year period in which human pressures on the Sierra have been greatest, nature has been unusually beneficent.

“During the period of settlement of the Sierra Nevada, climate was much wetter, warmer and more stable,” the study says. Recent droughts could be a harbinger of tough times ahead. “Periods of century-long droughts have occurred within the past 1,200 years and may recur in the near future.”

The study could have its most immediate impact on management of the national forests that extend over 40% of the region. Under heavy pressure from environmental groups, the Clinton administration recently postponed the adoption of a pending U.S. Forest Service plan that was expected to significantly increase the amount of logging permitted in the Sierra.

Environmentalists had hoped the Sierra study would recommend placing all remaining old-growth trees off limits to logging. The study’s proposed reserve system, however, does not go that far.

It calls for a system of national forest reserves--each 20,000 to 60,000 acres in size--to protect what the authors regard as some of the region’s biologically richest resources.

The reserves would encompass remaining old growth, which is scattered across most of the 430-mile-long mountain range, but would also include younger trees in the belief that the healthiest forests are a complex mix of stands.

The study calls for stricter limits on logging old growth than would be in effect under the Forest Service’s pending plan, but it would not ban logging.

A Forest Service official said Friday that the agency would devote at least a week to studying the new report to determine if changes should be made in the forest plan for the Sierra.

Air pollution bears some of the blame for deteriorating forest conditions, as ozone weakens Jeffrey and ponderosa pines along the western slope of the mountains. But air pollution from a variety of sources--many outside the Sierra--are also blamed for reducing visibility and degrading the quality of Sierra lakes.

In response to these problems, the study recommends enforcement of California’s ozone standard as opposed to the weaker federal regulation.

“The federal ozone standards for human health may be inadequate to protect biota [plant and animal life] from air pollution damage,” the report says.

In addition, it calls for enforcing limitations on sulfur emissions from oil refineries and chemical plants in the Bay Area and the San Joaquin Valley, eliminating agricultural burning during the summer and continuing efforts in Sierra communities to reduce emissions from fireplaces and wood-burning stoves.

According to the study, expected population growth of 650,000 to 2 million over the next 50 years could have the most serious consequences for the Sierra environment.

The report faults the fastest-growing local communities for not monitoring the effects of that growth on the environment. Those effects, it says, include conversion and fragmentation of wildlife habitat, invasion of nonnative plants and animals and damage to watersheds from construction and contamination from overtaxed sewer systems.

Among its recommendations, the study puts forward a “slow growth” strategy that would put new limits on development in “flammable wild lands” and scale back by 40% the amount of land now being made available for new construction.

At the present rate of growth, the study says, nearly half of the remaining open land will be consumed by human settlement.