Hubbard Brook, NH (USA) 1955 -
Location and Scale
Hubbard Brook, West Thornton, New Hampshire, USA in the White Mountains National Forest 3037 ha with several subcatchments
1955 to present
Annual precipitation averages about 1,400 mm, of which about one third to one quarter is snow. Approximately 111 separate storms occur each year, or about 2 storms per week. A snowpack usually persists from mid-December until mid-April, with a peak depth in March of about 1,020 to 1,270 mm, having about 250 to 300 mm of water content.
Winters are long and cold. January averages about -9oC, and long periods of low temperatures from -12˚C to -18˚C are common. Even though temperatures are low most of the time, occasional midwinter thaws result in elevated streamflo. Short, cool summers are the rule. The average July temperature is 18oC.
The average number of days without killing frost is 145; however, the growing season for trees is considered to be from 15 May, the approximate time of full leaf development, to 15 September, when the leaves begin to fall.
The estimated annual evapotranspiration (ET) is about 500 mm, determined by difference between precipitation and streamflow. This calculation is a reasonable approach for Hubbard Brook because of the apparent minimal deep seepage and annual removal of summer soil-water deficits by autumnal rains and spring snowmelt.
Geology and Soils
The eastern portion of the Experimental Forest (watersheds 1-6, and 9 included) is underlain by a complex assemblage of metasedimentary and igneous rocks. The major map unit is the Silurian Rangeley Formation, consisting of quartz mica schist and quartzite interbedded with sulfidic schist and calc-silicate granulite. Originally deposited as mudstones, sandstones and conglomerates, these rocks have been metamorphosed to sillimanite grade and have undergone four stages of deformation. Deformation style evident in outcrops is primarily tight isoclinal folds. However joints, slickensides and mylonites indicate brittle deformation as well. The metamorphic rocks were later intruded by a variety of igneous rocks including the Devonian Concord Granite, pegmatites, and Mesozoic diabase and lamprophyre dikes. The western portion of the forest (portions of watersheds 7 and 8 included) is underlain by the Devonian Kinsman Granodiorite, a foliated granitic rock with megacrysts of potassium feldspar.
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 (600 meters (2,000 ft)). 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).
The bowl-shaped forested valley has hilly terrain, ranging from 222 to 1,015 meters (728 to 3,330 ft) in altitude. The larger catchment area comprises nine individual watersheds, each of which drains into Hubbard Brook, and then through Mirror Lake, before emptying into the Pemigewasset River near West Thornton.
== Vegetation / Land Use 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 meters (1,870 ft), 570 to 650 meters (1,870 to 2,130 ft), and 720 meters (2,360 ft), respectively, with paper birch, fir, and spruce at 720m to treeline (>775 meters (2,543 ft)). 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 m³) of timber had been harvested from the valley.
In early August, 1954, the North Eastern Forest Experimental Station (NEFES) named Howard Lull, who had been working at the Southern Forest Experiment Station, as Chief of the Division of Watershed Management (based on NEFES annual reports, the position had remained vacant since its establishment in 1951). Lull stayed with NEFES through the late 1960's, earning an international reputation in forest hydrology for both himself and NEFES (including organising the International Symposium of Sopper and Lull 1967). Coinciding with but unrelated to Lull's arrival, Congress appropriated $350,000 to establish watershed management studies in the White Mountains of New England.
By late August, 1954, Lull (who had only begun work in early August), Herb Storey of the Forest Service Washington Office, and C. L. Graham, Supervisor of the White Mountains National Forest were touring the WMNF selecting potential sites for watershed management studies. They narrowed the field to six possibilities. Unfortunately the names of the candidate sites (except for HBEF) and the selection criteria seem to be lost. Lull, Victor Jensen, head of the White Pine-Hardwood Research Center, and George R. Trimble, who had been detailed from the earlier Fernow watersheds, chose the Hubbard Brook watershed as best suited for research needs. Research at Hubbard Brook was to be administered by and headquartered with the White Pine-Hardwood Research Center located in Laconia, New Hampshire.
Trimble was selected as Project Leader and began official duties on November 10, 1954. Richard Sartz transferred from the Forest Service, Washington Office Photo Interpretation Project and reported for work October 10, 1954. Robert Pierce who had been working with Lull at the Southern Forest Experiment Station, was recruited by Lull and arrived for work January 23, 1955. Carol Pierce remembers that within a week of his arrival, Bob was on snowshoes at Hubbard Brook assisting Trimble and Sartz in defining watershed boundaries and measuring snow courses. Sartz remembers first attempts at marking snow courses with tree blazes, only to have them nearly covered with subsequent snowfalls.
Trimble noted that an important part of the HBEF program would be conducting "show-me- trips". A soil survey of the entire HBEF was conducted in the summer of 1955 by Bob Pierce together with Frank Vierra, Sid Pilgrim, and Lloyd Garland of the U.S. Soil Conservation Service (procedures are described in Garland et al. 1959). Geologists Edward Bradley and R.V. Cushman with the U.S. Geological Survey completed a geologic survey of HBEF in 1956. Aerial photos of the Hubbard Brook watershed were taken on November 10, 1954 and used to help locate experimental watersheds. A detailed topographic map of HBEF was made from another set of aerial photos taken in May, 1956. Dick Sartz helped with triangulation procedures used in making the map. Weir construction began in the summer of 1955 and watersheds 1, 2, and 3 were being gauged by 1958. The jeep road to the early weirs served as a study site for road erosion. Gauges were added to five additional watersheds in the 1960's.
The early field headquarters at HBEF was the Kendall cottage located on the Mirror Lake Road, across from Mirror Lake. The cottage served as office, storage, and temporary living quarters. In 1958 the Forest Service purchased an additional 55 ha of land adjoining HBEF on the southeast. This land is the site of the current HBEF headquarters buildings, including the barn, sample archive building, and the Robert S. Pierce Ecosystem Laboratory.
Early personnel at HBEF shifted fairly rapidly. Trimble left in 1957 to become a Center Leader in West Virginia and Sartz left in 1958 to become a Center Leader in the Lake States. Bob Pierce became Project Leader in 1958 and served in that capacity until 1991. Ray Leonard arrived in 1957 and began studies of canopy interception and stemflow. Tony Federer began his HBEF career as a "student trainee" in the summers of 1958 and 1959.
Research at HBEF for the first 5 or 6 years after establishment focused solely on effects of forests on components of the hydrologic cycle, erosion, and water quality. In the late 1950's, Herb Bormann, A Professor at Dartmouth College, began bringing his ecology classes to view the research at Hubbard Brook. In the early 1960's, Bormann's visits to HBEF evolved into a cooperative research effort involving himself, Bob Pierce, and Gene Likens and Noye Johnson, two faculty members also located at Dartmouth. Together they began using the gauged watersheds at HBEF as experimental ecosystems for studies of elemental budgets and cycles (Bormann 1996). These studies would expand and eventually involve hundreds of cooperators and become known as the Hubbard Brook Ecosystem Study. The HBES added a new dimension to paired watershed studies and brought international recognition to HBEF.
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". HBRF was designated as a Long-Term Ecological Research (LTER) site in 1988 and has some of the longest on-going ecological datasets.
Likens, G. E. and F. H. Bormann. 1995. Biogeochemistry of a Forested Ecosystem. Second Edition, Springer-Verlag New York Inc. 159 pp
Bormann, F.H. 1996. Ecology: a personal history. Annual Review of Energy and Environment 21:1-29.
Federer, C.A. 1969. New landmark in the White Mountains. Appalachia 36:589-594.
Garland, L.E., R.S. Pierce, and G.R. Trimble, Jr. 1959. A soil survey of forest land. Journal of Soil and Water Conservation 14(5):199-204.
Richard T. Holmes, Gene E. Likens, 2016, Hubbard Brook The Story of a Forest Ecosystem, Yale University Press, ISBN: 9780300203646
Likens, G.E. 1972. Mirror Lake: its past, present, and future? Appalachia 39(2):23-41.
Sopper, W.E., and H.W. Lull, eds. 1967. International Symposium on Forest Hydrology. Pergammon Press, New York. 813 p.
Trimble, G.R., Jr. 1955. Watershed research begins in New Hampshire. Society for the Protection of New Hampshire Forests, Forest Notes no. 46, 4p.