The weak economy has taken a big bite out of the Wilderness Society, which last week laid off 17 percent of its staff.

Headquartered in Washington, the organization is one of the nation's most venerable land preservation groups and has been a major force behind the creation and expansion of the federal wilderness system.

After increasing its staff and spending in recent years, the group is retrenching. "The Wilderness Society, like so many other organizations, has been feeling the effects of a down economy, creating budget pressures," said Kitty Thomas, senior director of advocacy communications. "We had an obligation to meet these financial challenges."

Thomas declined to provide details of the layoffs but said the staff had been trimmed to 155, about the size it was five years ago. Thirty-two people lost their jobs across the organization, which has nine regional offices. The cuts included a number of positions in the Denver office and in Washington, as well as one in California, according to staff members.

"We believe that we have emerged from the process with an organization that is more focused on its priorities," Thomas said.

The layoffs were announced a month after William Meadows, the organization's president, announced that he would step down next year from the post he has held since 1996 and move into an advisory position. The group has launched a search for his replacement.

The society's financial troubles and layoffs are not unique among nonprofit groups, which experienced a sharp drop in donations after the financial collapse and have yet to fully recover.

"Things really have not rebounded back to where they were before the recession started," said Stacy Palmer, editor of The Chronicle of Philanthropy, which just published its annual survey of big charities. "Some groups were able to do better than others. But even the ones that did well said they had to work three, four times as hard as they did in the past because of the economy. Donors are still uncertain."

Last year, the Chronicle found that wealthy donors making large gifts contributed only one-third of what they did in 2008.

The Wilderness Society's base has remained fairly steady, at about 500,000 members and supporters. But the bottom line has not because some major multiyear gifts ended, Thomas said.

According to the group's audited financial statement, expenses outstripped revenue of $23 million by about $2.3 million in fiscal year 2010. Thomas said she could not provide the most recent revenue figures because they had not been audited.