The plan unveiled by President Bush earlier this week to make it easier to thin forests in the name of fire prevention has touched off a firestorm of its own, enraging environmentalists who see it as a giveaway for the timber industry and a backdoor out of environmental protection measures. Moreover, environmentalists see the Bush plan as a Trojan horse for sneaking a highly controversial timber practice into American forests — salvage logging, or the selling of trees in fire-damaged forests. Advocates of salvage logging say it is a way for the U.S. Forest Service to make money off of wood that might otherwise simply rot; conservationists compare salvage logging to mugging a fire victim. They say timber companies remove large, fire-resistant trees and fallen logs that help restore ecosystems, and leave precisely the smaller trees and underbrush that pose a fire hazard.