Forests produce many goods and services: clean water for drinking; habitat for plants and animals; wood for paper, packaging, and building; recreational opportunities; and cultural and spiritual benefits.

This section provides a summary of findings regarding the use and condition of America's forests and the additional information needed to enable us to better understand them.

The information provided here is the most recent available. Late in 1999, the Forest Inventory and Analysis Program run by the U.S. Department of Agriculture Forest Service will complete its work on data collected in 1997. These data will be included in the 2001 report.

Forests cover about one-third of the United States, roughly 70 percent of their extent at the time of European settlement. Forest acreage declined slightly from 1977 to 1992.

Western forests are predominantly public; eastern forests are predominantly private.

About 40 percent of U.S. forest lands are publicly owned. Of these, roughly 15 percent are in "strictly protected" areas, primarily national parks and wilderness areas where timber harvest is permanently prohibited. Other public forest lands are managed for various uses, including recreation, grazing, watershed protection, timber production, wildlife habitat, and mining.

Private forests are owned by forest products companies, other firms, and individual landowners. Timber production or land investment are primary reasons for ownership on 39 percent of private forest lands. Many private forest lands (18 percent) are owned as part of a farm or residence, or for recreation and enjoyment (17 percent). Landowner participation in voluntary conservation programs is growing but is not well quantified.

Fragmentation of forests into smaller, more isolated patches can create barriers to species movement, introduce predators and parasites, and reduce wildlife habitat. Research is at an early stage and there is little consensus on appropriate measures. Two possible measures are described.

Timber harvest and wood use have increased over recent decades, with much of the increase used for paper products. The South provides an increasing proportion of the Nation's timber, while the West's share is declining. Harvests on private lands have increased since 1962, whereas harvests on public lands have declined since the 1980s. More products are being produced from every tree harvested and the proportion of paper recycled is increasing.

Recreation is an important use of public and private forests, but there are no comprehensive data on important measures such as current use levels, accessibility, and forests' capacity to support recreational use. Most land agencies manage both forest and nonforest areas, but they generally do not break down visitation data into these categories.

Water quality generally improves with increases in the percentage of a watershed that is forested. Thus, for watersheds that provide surface water for drinking, we propose two measures of water quality protection: the percentage of the watershed with forest cover and the percentage of stream banks that are forested. Data are quite limited, however.

Each year, about 2 percent of the Nation's timber is cut, and a slightly larger amount regrows. Nationally, the extent to which growth exceeds harvest has declined since the 1970s, with significant regional differences. U.S. forests continue to add to their stores of carbon, but at a decreasing rate, while the rate at which carbon is stored in wood products and paper in landfills is increasing.

Industry-managed forests have higher tree growth rates than do other lands. Average growth rates across all owners have increased (since the 1950s and 1960s).

Stream nitrate concentrations in the few forested watersheds that are monitored are generally far below drinking water standards, and much lower than in urban or agricultural areas. More extensive data will be available in the future.

There are no comprehensive national data on forest soil properties. Monitoring is difficult because intensive sampling is needed to account for natural variability.

High levels of ozone can change forests by reducing the growth of ozone-sensitive plants. Pilot surveys found symptoms of ozone injury in New England, the Great Lakes region, and the western Mid-Atlantic region. No consistent national information is available, but such data will be available in the future.

The area of forest burned by wildfires is much lower today than it was in the 1920s and 1930s. In recent years, the area of forest affected by wildfires in National Forests, which are mostly in the West, has been increasing.

About one-fourth of U.S. "Forest associations" - unique plant communities - are "critically imperiled" or "imperiled," indicating that an association occurs in 20 or fewer places, has few remaining acres, or is vulnerable for other reasons. About 30 percent are "secure" or "apparently secure."

Status and trend data for birds is generally better for birds than for other wildlife. In general, for forest birds of prey, birds that prefer mature forest, and birds that prefer forest edges, more species are increasing than decreasing.

No consistent national information is available on the ranges and populations of most forest carnivores, the amount of old-growth forest, or the number of trees of various sizes (including very large trees).

Insects and diseases affect human uses and ecological functions of forests. Five species of insects affect about 3 percent of U.S. Forests (21 million acres) a year. One disease (fusiform rust) affects about 6 percent of southern forests, and one parasitic plant (dwarf-mistletoe) affects roughly 12 percent of forests in the West. Data on insect damage are more complete than are those on diseases.

Biological invasions by nonnative species can also substantially alter forests. Nonnative plants make up one-fourth of the smaller trees and shrubs in California and 20 percent of those in the Mid-Atlantic region. A few nonnative organisms such as the chestnut blight have dramatically changed U.S. Forests An example of a new invader is the Asian longhorned beetle, which damages maple and other hardwoods and has been found in imported packing materials and native trees.

The table on the next page provides a listing of the measures presented in greater detail on the following pages. Additional information on each measure is in the Technical Notes.