to as the "Hubbard Brook Ecosystem Study", or HBES. The early ecosystem monitoring was aimed at studying the effects of forest management practices on water flow and quality. These data have been helpful as baselines for the increasingly sophisticated areas of ongoing research in the forest. HBES has spawned over 2000 scientific papers, perhaps most important a 1968 study that documented the widespread presence of "acid rain". HBRF was designated as a Long-Term Ecological Research (LTER) site in 1988 and has some of the longest on-going ecological datasets. Currently the study comprises researchers from multiple universities, including Dartmouth College, Yale University, Cornell University, Syracuse University, SUNY ESF, the University of New Hampshire, Keene State College and the University of Vermont. The Hubbard Brook Research Foundation provides housing for research assistants at nearby Pleasant View Farm and recently completed the purchase of cottages for visiting and resident scientists around Mirror Lake, the point at which Hubbard Brook exits the experimental forest. Hubbard Brook Experimental Forest is the most recently added research forest under USFS jurisdiction for hydrologic studies in the eastern and southern United States. Hubbard Brook ecosystem Located in the White Mountain National Forest in central New Hampshire, within the town of Woodstock, the bowl-shaped forested valley has hilly terrain, ranging from in altitude. The forest comprises nine individual watersheds, each of which drains into Hubbard Brook which flows eastward into the Pemigewasset River near West Thornton. The outlet from Mirror Lake, a much-studied pond and recreation site, flows south into Hubbard Brook just before the brook passes under Interstate 93. Forest The forest is mostly a "second-growth" mix of northern hardwoods (80 to 90%) and red spruce-balsam fir (10 to 20%). Beech, yellow birch, and sugar maple experience their greatest importance at , , and , respectively, with paper birch, fir, and spruce at 720m to treeline (>). Mountain maple, striped maple, and mountain ash characterize the understory at various elevations, with mountain maple being ubiquitous. Five of the seven canopy species are valued for various reasons. Harsh winter conditions do not allow for rapid recovery, unlike more humid climates that recover net primary productivity within years, the northeastern version needs decades and in the case of the forest floor possibly centuries to recover. The forest was partly cleared for agriculture starting in the late 18th century and was also logged. By 1920 over 200 million board feet (470,000