Just what, exactly, is a "sofa designed for the home we call Earth"? And what is so "sustainable" about the wood in it?

The home goods industry has become just as enamored with green buzzwords as the food and fashion worlds have, and "sustainable wood" is one of the most common marketing cries. (Crate and Barrel makes that particular sofa for earth out of not just wood that is certified by the Sustainable Forestry Initiative but also from "revolutionary, bio-based materials that are environmentally renewable.")

Some wood, of course, is more sustainable from others. Here's what you need to know.

— Generally, sustainable wood means wood harvested from carefully managed forests or reclaimed from old buildings or furniture.

"There are a number of programs that certify the way timber is cut down and used," said Deb Snoonian, executive editor of Plenty magazine, which covers green topics. "They have guidelines on how forests should be managed, and the idea is that you never want to clear-cut a forest."

— Look for proper certification, often in the form of a label.

The most stringent of these programs, she said, is run by the Forest Stewardship Council. "The FSC guidelines are the ones most environmental groups trust," Snoonian said.

The FSC offers a searchable database of certified vendors, says Katie J. Miller, the organization's U.S. communications director.

— Ask where the wood comes from.

Even without certification, customers can assume that most wood grown in North America is likely to be harvested in an environmentally safe way, said Ron Jarvis, vice president of environmental innovation at The Home Depot, which sells some FSC-certified wood.

"If you're buying Southern yellow pine or redwood or cedar, probably it's OK without certification," he said.

Be careful with woods that may have been harvested in countries lacking stringent environmental rules, Jarvis added.

"If you're going in to buy a wood product and you're not familiar with the name or it's a name that usually means rain forest, like teak, ask for an FSC-certified product," he said

Bill Banzhaf, president of the Sustainable Forestry Initiative, one of the country's largest certifying organizations, says the more customers ask about sustainable wood, the more it will create a market for good practices.

"There is a great deal of material out there. Sometimes it's not labeled because a manufacturer doesn't want to confuse the consumer or wants to support their own brand."

Besides certification, Banzhaf says the SFI's program also trains loggers — 97,000 so far — to harvest wood in an environmentally safe way.