Associated Press: University of Maine researchers are studying the impact of hemlock tree die-offs on the state's freshwater forests. UMaine stream ecology assistant professor Hamish Greig and Climate Change Institute Jacquelyn Gill are leading the researchers as they study past and present declines of the trees. The trees are threatened by pests that have also decimated the species in the southeastern states. Gill says warmer temperatures have allowed the hemlock woolly adelgid to gain a foothold in Maine. The...