A University of Vermont researcher says red spruce forests in the Northeast that were once damaged by acid rain are recovering, thanks to stronger pollution controls. In the early days of acid rain research, red spruce trees on Camel’s Hump in Vermont were seen as the canaries in the coal mine. The conifers were dying from acid rain, caused by pollutants released mainly by Midwest fossil fuel power plants. The late UVM scientist Hubert “Hub” Vogelmann documented the trees’ decline on Camel’s Hump. His research provided compelling evidence of the environmental impact of acid rain. But 1990 amendments to the federal Clean Air Act limited nitrous oxide and sulfur dioxide emissions. And now the trees are recovering. …one reason the trees are showing increased growth is due to a longer growing season related to climate change.