Two environmentalist groups have separately asked the Sustainable Forestry Board to revoke Sustainable Forestry Initiative certificates held by Plum Creek Timber and Weyerhaeuser, according to The Washington Post.

Plum Creek’s forestry practices have been challenged by the Natural Resources Council of Maine. The organization reportedly contends that Plum Creek has violated rules, including excessive cutting of timber without filing proper plans and failing to notify the state of Maine about clear-cuts at forests Plum Creek owns.

The Seattle Audubon Society said Weyerhaeuser cut trees in forests that are home to northern spotted owls, which are protected by the Endangered Species Act.

Representatives for Plum Creek and Weyerhaeuser each told the Post that their companies are practicing sustainable forestry in line with their SFI certifications.

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