Al Gore made a hard pitch to enviros during an impassioned campaign speech in Portland, Ore., last night, pledging to protect old-growth trees, roadless forest areas, and salmon runs. “When it comes to the environment, I’ve never given up, I’ve never turned back, and I never will,” Gore told a crowd of nearly 4,000, in an apparent bid to convince voters to support him rather than Green Party candidate Ralph Nader. “Nowhere are the differences between me and Gov. Bush clearer than on the environment,” Gore continued. Gore didn’t address the controversial issue of dams on the lower Snake River in Washington state. Enviros want them breached to help salmon; Gore has said that the issue needs more study and that he would convene a salmon summit in the Northwest to explore ways to save the fish.