More likely than not, visitor photos of Acadia National Park include trees, whether the sharp spires of spruce and fir perched atop Otter Cliffs, streaks of pitch pines on the ledges of the Beehive, gnarled birches on Cadillac Mountain, or the jack pines at Schoodic Point. Yet the forest is more than background scenery, more than the landscape to travel through on the way to the summit or roots to trip over on the path to the swimming hole. Simply put, Acadia would not be Acadia if not for the trees. The most common ecosystem across the park, forests support a diversity of wildlife, protect lakes and streams, clean the air, and pull carbon dioxide out of the atmosphere. All forests, of course, have these functions. But it turns out Acadia's woods, protected for well over a century, are special for many reasons. Though the evergreen forest of spruce and fir covers most of the park, Acadia's woods are not uniform. This is not one forest, but many. How many visitors know they are surrounded by some of the oldest and healthiest forests in the eastern United States? That Acadia's trees, in a transition zone between northern boreal forest and southern temperate forests, support a unique assemblage of plants, animals, lichen, and moss? Or that concern for the future of the trees inspired creation of the park more than a century ago? Or that the future of these special woodlands is at risk? Acadia's forests are cared for by park scientists who measure and monitor trees to ensure their future-a future of increasing uncertainty in a changing climate. Their work, the science behind the scenery, has generated an incredible amount of knowledge about Acadia's trees that until now has been buried in scientific papers and technical reports. With these experts as guides, and with history and hundreds of original, full-color photos as inspiration, travel the trails of Acadia to learn about trees through all four seasons, from the balsam fir on the summit of Cadillac Mountain and blazing maples of the Jesup Path in autumn, to hemlocks toppled by winter storms and ash trees illuminated by spring sunlight. Readers of Trees of Acadia will gain a new understanding of and appreciation for the trees and forests of Acadia National Park, and in turn for forests everywhere.