Environmentalists and some residents of Sonoma County have identified the latest threat to nature: wine. They oppose efforts by winemakers to convert forests into vineyards, saying they would destroy wildlife habitat, cause soil erosion, and generate pesticide pollution. County supervisors are set to consider rules blocking the cutting of firs and redwoods for vineyards and allowing lands with other types of trees to be converted to grape growing only if the move "benefits the public" and if the owner plants two new acres of trees for every one of grapes. Environmentalists say those restrictions are too weak.