WASHINGTON (Reuters) - Paper products giant Kimberly-Clark Corp joined forces with Greenpeace on Wednesday, pledging to conserve forests by getting wood fiber from environmentally responsible sources.

A bush plane flies just above the water through trees of the boreal forest north of Whitehorse, Yukon in this file photo taken June 21, 2007. REUTERS/Andy Clark/File

In an announcement with the environmental group, which waged a nearly 5-year campaign against the company for clear-cutting in Canada’s boreal forest, Kimberly-Clark said it would stop buying wood fiber from the vast woodland which stretches across the country unless it is certified by the Forest Stewardship Council.

“We are a 100-plus-year-old company. We want to be around here for another 100-plus years or more, and the only way we can be is by using sustainable forest practices,” Kimberly-Clark’s Suhas Apte, vice president of global sustainability, said in a telephone interview.

Kimberly-Clark is among the world’s largest paper-products manufacturers, including such brands as Kleenex, Scott and Cottonelle.

The company pledged to get all its wood fiber for tissue products from environmentally responsible sources, increasing the use of recycled fiber and certified fiber.

By the end of 2011, the company said 40 percent of its North American tissue fiber -- about 600,000 tonnes -- will be either recycled or certified, an increase of more than 70 percent over 2007 levels.

Forest conservation is considered a key weapon against climate change, because forests lock up over 20 percent of all human-generated carbon dioxide, a greenhouse gas that spurs global warming when it gets into the atmosphere.

CONSERVING CANADIAN FOREST

The trees and soil of Canada’s boreal forest store some 186 billion tonnes of carbon, equivalent to 27 years of global greenhouse gas emissions, said Richard Brooks of Greenpeace Canada.

“Canada’s boreal forest is the largest ancient forest left in North America,” Brooks said in a statement. “Though vast, already 60 percent is allocated to logging companies for development. Less than 10 percent of the forest is permanently protected.”

Kimberly-Clark’s new standards could bring some of the unspoiled areas of the forest closer to permanent conservation, Brooks said.

“There’s a cultural difference between a group like Greenpeace and a group like Kimberly-Clark,” said Scott Paul, director of Greenpeace USA’s Forest Campaign. “But we were able to find ... a path forward that truly pushed Kimberly-Clark down a road of greater and greater sustainability but allowed them to pursue a business model that allowed the quality products people expect.”

Greenpeace’s “Kleercut” campaign against Kimberly-Clark began in November 2004 and featured such eye-catching actions as setting up a “forest crime scene” outside the company’s Canadian headquarters and a print ad in The New York Times that told readers they were destroying the boreal forest every time they used Kleenex tissue.

The environmental group ended the campaign on Wednesday with a video posted at www.greenpeace.org/kleercut

The change comes four months after Kimberly-Clark introduced a line of paper products using recycled material.