In 1960, soon after the establishment of HBEF, ecologist Gene Likens and geologist Noye Johnson, both from Dartmouth, joined the research team. In 1963, the group received a $60,000 grant from the National Science Foundation to study "Hydrological-Mineral Cycle Interaction in a Small Watershed". This study evolved into the series of longitudinal studies now referred 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".
Currently the study comprises researchers from multiple universities, including Dartmouth College, Yale University, Cornell University, Syracuse University, S.U.N.Y., University of New Hampshire, and 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.
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 570, 570~650, and 720m, respectively, with paper birch, fir, and spruce at 720 to treeline (>775m). 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 late 1700s and was also logged. By 1920 over 200 million board feet (470,000 m³) of timber had been harvested from the valley.
Soil is predominantly well-drained Spodosol derived from glacial till, with sandy loam textures, combining to produce an evident, but narrow E horizon. The forest floor is characterized by the complete suite of taxonomic subhorizons, has been classified as mor type humus, with mull occurring beneath maple stands at lower elevations (600m). It is acidic (pH about 4.5 or less) and relatively infertile for agricultural purposes. Aluminum and iron are preferentially leached from the upper soil horizons to an underlying layer(s) that is characteristic of the soil order. Hence, Silica is retained and at times mixes with the forest floor. Soil depths are highly variable, with shallow strands of organic matter comprising the entire profile at higher elevations (folist) or underlain by sandy unsorted material (podzol).
Annual precipitation averages about 1,400 mm, with one-third to one-quarter as snow. January averages about -9 °C and the average July temperature is 18 °C. The Forest averages 145 frost-free days per year.
Links between Biomass and Tree Demography in a Northern Hardwood Forest: A Decade of Stability and Change in Hubbard Brook Valley, New Hampshire
Jul 01, 2011; Introduction Recent reports that live-tree biomass has stopped accumulating at the Hubbard Brook Experimental Forest in the White...
Calcium addition at the Hubbard Brook Experimental Forest reduced winter injury to red spruce in a high-injury year.
Oct 01, 2006; Abstract: Laboratory experiments have verified that acid-deposition-induced calcium (Ca) leaching reduces the foliar cold...