Progress 10/01/06 to 09/30/07
Outputs
Conducted a scientific meeting on research at Hubbard Brook Experimental Forest with 50 presentations and about 130 participants. Staff at Hubbard Brook Experimental Forest conducted 45 site visits (field trips and tours of the forest) by college classes and other groups. About 550 people participted in the tours.
Impacts
1) We quantified the dynamics of the tree stratum at Hubbard Brook Experimental Forest (HBEF), New Hampshire, to examine why live biomass reached a plateau in about 1980. Total aboveground biomass increased from 209 Mg/ha in 1981 to 216 Mg/ha in 2001. From 1991 to 2001, in-growth of ≥10 cm diameter at breast height (DBH) trees averaged 4.7 trees/ha/year with a corresponding in-growth biomass of 0.29 Mg/ha/year. Mortality of trees larger than 10 cm DBH averaged 5.3 trees/ha/year (1.12% of trees/year). Dying trees represented 2.24 Mg/ha/year of aboveground biomass from 1991 to 2001. The biomass pools of standing dead, snags, and coarse woody debris in this forest currently are near steady state with residence times of 7.5, 15, and 6.2 years, respectively. The plateau in live biomass was mostly associated with lower wood production. Aboveground net primary productivity was estimated at 6.53 Mg/ha/year, considerably lower than published estimates for the 1956-1965
period at the HBEF. Net ecosystem productivity in this young, second-growth forest is near zero, indicating that it may not be a sink for carbon. 2) While commonplace in other parts of the world, long-term and ongoing observations of the phenology of native tree species are rare in North America. We use 14 years of field survey data from the Hubbard Brook Experimental Forest to fit simple models of canopy phenology for three northern hardwood species, sugar maple American beech and yellow birch. These models are then run with historical meteorological data to investigate potential climate change effects on phenology. Sugar maple is the first species to leaf out in the spring, whereas American beech is the last species to drop its leaves in the fall. More than 90% of the variation in spring canopy development, and just slightly less than 90% of the variation in autumn canopy senescence, is accounted for by a logistic model based on accumulated degree-days. Retrospective modeling using
five decades (1957-2004) of Hubbard Brook daily mean temperature data suggests significant trends towards an earlier spring (e.g. sugar maple, rate of change .18 days earlier/yr), consistent with other studies documenting measurable climate change effects on the onset of spring in both North America and Europe. Our results suggest that green canopy duration has increased by about 10 days over the period of study.
Publications
- Richardson, Andrew D.; Bailey, Amey S.; Denny, Ellen G.; Martin, C. Wayne; and O'Keefe, John. 2006. Phenology of a northern hardwood forest canopy. Global Change Biology (2006) 12, 1174-1188
- Siccama, Thomas G., Fahey, Timothy J., Johnson, Chris E., Sherry, Thomas W., Denny, Ellen G., Girdler, E. Binney, Likens, Gene E., and Schwarz, Paul A. 2007. Population and biomass dynamics of trees in a northern hardwood forest at Hubbard Brook. Can J. For. Res. 37:737-749
- McCutcheon, S.C., Tedela, N., Adams, M.B., Swank, W. Campbell, J.L., Hawkins, R.H., Dye, C.R. 2006. Rainfall-Runoff Relationships for Selected Eastern U.S. Forested Mountain Watersheds: Testing of the Curve Number Method for Flood Analysis. Report Prepared for the West Virginia Division of Forestry, Charleston, West Virginia, October 2006.
- Fisk, M. C., Kessler, W. R., Goodale, A., Fahey, T. J., Groffman, P. M. and Driscoll, C. T. 2006. Landscape variation in microarthropod response to calcium addition in a northern hardwood forest. Pedobiologia 50(1): 69-78.
- Phillips, R.P. and Fahey, T.J. 2006. Tree species and mycorrhizal associations influence the magnitude of rhizosphere effects. Ecology 87(5):1302-1313
- Boyce Richard L. 2007. Chlorophyll fluorescence response of red spruce and balsam fir to a watershed calcium fertilization experiment in New Hampshire Can J. For. Res. 37:1518-1522
- Dittman, J. A., Driscoll, C. T., Groffman, P. M. and Fahey, T. J. 2007. Dynamics of nitrogen and dissolved organic carbon at the Hubbard Brook Experimental Forest. Ecology. 88(5): 1153-1166
- Judd, Kristin E., Likens, Gene E. and Peter M. Groffman. 2007. High Nitrate Retention during Winter in Soils of the Hubbard Brook Experimental Forest. Ecosystems. 10: 217-225
- Groffman, P. M. Hardy, J. P., Driscoll, C. T. and Fahey, T. J. 2006. Snow depth, soil freezing, and fluxes of carbon dioxide, nitrous oxide and methane in a northern hardwood forest. Global Change Biology. 12:1748-1760, doi: 10.1111/j.1365-2486.2006.01194.x
- Dobbs, Robert C., Sillett, T. Scott, Rodenhouse, Nicholas L. andHolmes Richard T. 2007. Population density affects foraging behavior of male Black-throated Blue Warblers during the breeding season. J. Field Ornithol. 78(2):133-139
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Progress 10/01/05 to 09/30/06
Outputs
Watershed budget studies at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, have demonstrated high calcium depletion of soil during the 20th century due, in part, to acid deposition. Over the past 25 years, tree growth (especially for sugar maple) has declined on the experimental watersheds at the HBEF. In October 1999, 0.85 Mg Ca/ha was added to Watershed 1 (W1) at the HBEF in the form of wollastonite (CaSiO3), a treatment that, by summer 2002, had raised the pH in the Oie horizon from 3.8 to 5.0 and, in the Oa horizon, from 3.9 to 4.2. We measured the response of sugar maple to the calcium fertilization treatment on W1. Foliar calcium concentration of canopy sugar maples in W1 increased markedly beginning the second year after treatment, and foliar manganese declined in years four and five. By 2005, the crown condition of sugar maple was much healthier in the treated watershed as compared with the untreated reference watershed (W6). Following high seed
production in 2000 and 2002, the density of sugar maple seedlings increased significantly on W1 in comparison with W6 in 2001 and 2003. Survivorship of the 2003 cohort through July 2005 was much higher on W1 (36.6%) than W6 (10.2%). In 2003, sugar maple germinants on W1 were about 50% larger than those in reference plots, and foliar chlorophyll concentrations were significantly greater. Foliage and fine-root calcium concentrations were roughly twice as high, and manganese concentrations twice as low in the treated than the reference seedlings in 2003 and 2004. Mycorrhizal colonization of seedlings was also much greater in the treated than the reference sites. A similar, though less dramatic, difference was observed for mycorrhizal colonization of mature sugar maples. These results reinforce and extend other regional observations that sugar maple decline in the northeastern United States and southern Canada is caused in part by anthropogenic effects on soil calcium status, but the
causal interactions among inorganic nutrition, physiological stress, mycorrhizal colonization, and seedling growth and health remain to be established.
Impacts
Recent declines in the health and recruitment of sugar maple in the experimental watersheds at the Hubbard Brook Experimental Forest in New Hampshire appear to be linked in part to the depletion of calcium in the soil and consequent reductions in soil pH. The addition of calcium to an experimental watershed increased maple health, growth, and survivorship. The mechanism of maple response to calcium addition was associated with improved mineral nutrition, with either higher calcium or lower manganese, or both, in foliage and fine roots. In seedlings, chlorosis was also eliminated. Furthermore, mycorrhizal colonization was greatly stimulated by the calcium fertilization treatment, as both seedlings and mature trees in reference sites adjacent to W1 had low levels of mycorrhizal hyphae and structures.
Publications
- Watmough, Shaun A.; Aherne, Julian; Alewell, Christine; Arp, Paul; Bailey, Scott; Clair, Thomas; Dillon, Peter; Duchesne, Louis; Eimers, Catherine; Fernandez, Ivan; Foster, Neil; Larssen, Thorjorn; Miller, Eric; Mitchell, Myron; Page, Stephen. 2005. Sulphate, nitrogen and base cation budgets at 21 forested catchments in Canada, the United States and Europe. Environmental Monitoring and Assessment. 109:1-36.
- Juice, Stephanie M.; Fahey, Timothy J.; Siccama,Thomas G.; Driscoll, Charles T.; Denny, Ellen G.; Eagar, Christopher; Cleavitt, Natalie L.; Minocha, Rakesh; Richardson, Andrew D. 2006. Response of sugar maple to calcium addition to northern hardwood forest. Ecology. 87:1267-1280.
- Dasch, Amanda A.; Blum, Joel D.; Eagar, Christopher; Fahey, Timothy J.; Driscoll, Charles T.; Siccama, Thomas G. 2006. The relative uptake of Ca and Sr into tree foliage using a whole-watershed calcium addition. Biogeochemistry. 80:21-41.
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Progress 10/01/04 to 09/30/05
Outputs
Integrated, long-term, ecological, hydrological, and biogeochemical studies have been done at the Hubbard Brook Experimental Forest since 1963 using the small watershed-ecosystem approach. Some biogeochemical results from these long-term studies are described in a paper published in Ecology, including approaches used for managing this large and complicated project. Some major biogeochemical findings of the Hubbard Brook Ecosystem Study are discussed briefly, including acid rain, and some biogeochemical research questions, opportunities, and challenges for the future are identified, including a recent whole-watershed addition of calcium silicate, weathering processes, and long-term trends in stream-water nitrate concentrations. Soil C fluxes were measured in a northern hardwood forest at the Hubbard Brook Experimental Forest to provide insights into the C balance of soils. Annual FCO2 for the undisturbed northern hardwood forest was estimated at 660 g C/m2/year . Low
soil moisture significantly reduced FCO2 on three of the measurement dates. The proportion of FCO2 derived from the forest floor horizons was estimated to be about 58%. Respiration of root tissues contributed about 40% of FCO2, with a higher proportion for mineral soil (46%) than for forest floor (35%). Soil C-balance calculations indicated a large C flux associated with root exudation plus allocation to mycorrhizal fungi (17% of total root C allocation); however, uncertainty in this estimate is high. The estimated proportion of FCO2 associated with autotrophic activity (52%) was comparable with that reported elsewhere (56%). From 1964 through 1994, the pattern of nitrate (NO3) export from Watershed 6 at Hubbard Brook Experimental Forest exhibited 10 years of high export (1968-1977) followed by 12 years of low export (1978-1989), with four spikes in 1970, 1973, 1976, and 1990. Disruptions of N cycling by soil freezing, insect defoliation, or drought have been suggested to explain this
pattern. We developed a model of nitrogen dynamics demonstrating that most of the long-term pattern can be reproduced without explicit consideration of these events. Comparisons of simulated N fluxes between high and low export years suggested that inorganic N input to the soil, from both atmospheric N deposition and N mineralization, was significantly higher during periods of high streamflow NO3 flux than in low periods. Simulated inorganic N pools and fluxes were also significantly higher in these periods. By swapping the time sequences of inorganic N input between high and low export years, it was shown that N mineralization, not atmospheric N deposition, drives the simulated long-term pattern. Although simulated nitrification showed a stronger relationship with measured streamflow NO3 flux than did N mineralization, nitrification rate depended upon availability of soil ammonium supplied from N mineralization. Because N mineralization in the model varies only with soil temperature
and moisture, we conclude that shifts in the interaction of these two variables over time produced the shifts in NO3 stream exports.
Impacts
Improved understanding of the processes that regulate biogeochemical cycles will provide a clearer understanding of how human-caused disturbances such as acidic deposition alter these processes and change the biogeochemical cycle.
Publications
- Fahey, T.J.; Tierney, G.L.; Fitzhugh, R.D.; Wilson, G.F.; Siccama, T.G. 2005. Soil respiration and soil carbon balance in a northern hardwood forest ecosystem. Canadian Journal of Forest Research. 35: 244-253.
- Hong, B.; Swaney, D.; Woodbury, P.B.; Weinstein, D.A. 2005. Long-term nitrate export pattern from Hubbard Brook watershed 6 driven by climatic variation. Water, Air, and Soil Pollution. 160: 293-326.
- Likens, G.E. 2004. Some perspectives on long-term biogeochemical research from the Hubbard Brook Ecosystem Study. Ecology. 85(9): 2353-2362.
- Lovett, G.M.; Likens, G.E.; Buso, D.C.; Driscoll, C.T.; Bailey, S.W. 2005. The biogeochemistry of chlorine at Hubbard Brook, New Hampshire, USA. Biogeochemistry. 72: 191-232.
- Phillips, R.P.; Yanai, R.D. 2004. The effects of AlCl3 additions of rhizosphere soil and fine root chemistry of sugar maple (Acer saccharum). 2004. Water, Air, and Soil Pollution. 159: 339-356.
- Wellington, B.I.; Driscoll, C.T. 2004. The episodic acidification of a stream with elevated concentrations of dissolved organic carbon. Hydrologic Processes. 18: 2663-2680.
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Progress 10/01/03 to 09/30/04
Outputs
Progress is reported for three elements: (A) The 3,160 hectare Hubbard Brook Experimental Forest (HBEF) in New Hampshire has been a prime area of research on forest and stream ecosystems since its establishment by the USDA Forest Service in 1955. Streamflow and precipitation have been measured continuously on the HBEF, and there are long-term datasets for air and soil temperature, snow cover, soil frost, solar radiation, wind speed and direction, and humidity. This information has provided the basis for hundreds of publications by Forest Service and cooperating scientists on numerous aspects of forest hydrology research as part of the ongoing Hubbard Brook Ecosystem Study. A report summarizing 45 years of hydrometeorological data was published. (B) One of the major challenges now facing forest ecosystem scientists and managers is to address the need for multiple ecosystem services over relatively large spatial and temporal scales; for example, whole national forests
over 50- to 100- year time frames. A new conceptual for the Hubbard Brook Ecosystem Study was developed that aids in the analysis of factors that influence ecosystem structure, function and services. This model has three main components: 1) controllers, 2) ecosystem pattern and process, and 3) ecosystem functions and services. The controllers are the factors that drive ecosystem pattern and process and are split into two groups, state factors and variable-stochastic factors. This new model will help to ensure a comprehensive approach to forest ecosystem analysis and will facilitate interactions of research with policy and management. (C) In acid-sensitive watersheds of the northeastern US, decreases in sulfur dioxide emissions and atmospheric deposition of sulfur have not been accompanied by marked changes in pH and acid neutralizing capacity. To better understand this phenomenon, long-term trends in soil solution and streamwater chemistry from Hubbard Brook Experimental Forest were
analyzed. Significant declines in strong acid anion concentrations were accompanied by declines in base cation concentrations in soil solutions. The magnitude of change varied with position in the landscape. Recovery, as indicated by increasing acid neutralizing capacity, was confined to solutions draining soils at mid-to-higher elevations. At lower elevations, declines in base cations were either similar to or exceeded declines in strong acid anions resulting in no change in acid neutralizing capacity. Changes in the chemistry of streamwater reflected changes in soil solutions. The pH of soil solutions and streamwaters either declined or did not change; therefore, pH-buffering processes, including hydrolysis of aluminum and possibly the deprotonation of organic acids, have prevented increases in drainage water pH despite considerable reductions in inputs of strong acids.
Impacts
Improved understanding of the biogeochemistry of sulfur is critical to understanding the effects of acidic deposition on forest and associated aquatic ecosystems in the Northeast. Reductions in sulfur dioxide emissions and resulting reductions in deposition of sulfate have resulted in reduced concentrations of sulfate in stream water. However, internal processes of sulfur accumulation in soils and subsequent release over time, combined with depletion of base cations will delay ecosystem recovery, even with further reductions in sulfur dioxide emissions.
Publications
- Bailey, A.S.; Hornbeck, J.W.; Campbell, J.L.; Eagar, C. 2003. Hydrometeorological database for Hubbard Brook Experimental Forest: 1955-2000. Gen. Tech. Rep. NE-305. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station. 36 p.
- Fitzhugh, R.D.; Driscoll, C.T.; Groffman, P.M.; Tierney, G.L.; Fahey, T.J.; Hardy, J.P. 2003. Soil freezing and the acid-base chemistry of soil solutions in a northern hardwood forest. Soil Science of American Journal. 67: 1897-1908.
- Jones, J.; Doran, P.J.; Holmes, R.T. 2003. Climate and food synchronize regional forest bird abundances. Ecology. 84(11): 3024-3032.
- Likens, G.E.; Buso, D.C.; Dresser, B.K.; Bernhardt, E.S.; Hall, R.O.; Macneale, K.H.; Bailey, S.W. 2004. Buffering an acidic stream in New Hampshire with a silicate mineral. Restoration Ecology. 12: 419-428.
- Palmer, S.M.; Driscoll, C.T.; Johnson, C.E. 2004. Long-term trends in soil solution and stream water chemistry at the Hubbard Brook Experimental Forest: relationship with landscape position. Biogeochemistry. 68: 51-70.
- Peters, S.C.; Blum, J.D.; Driscoll, C.T.; Likens, G.E. 2004. Dissolution of wollastonite during the experimental manipulation of Hubbard Brook watershed 1. Biogeochemistry. 67: 309-329.
- Siccama, T.; Denney, E. 2004. Hubbard Brook LTER launches online education project. Network Newsletter. 16(2): 4.
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Progress 10/01/02 to 09/30/03
Outputs
A synthesis of the biogeochemistry of sulfur was done during 34 years (1964-1998) in reference and human-manipulated forest ecosystems of the Hubbard Brook Experimental Forest, New Hampshire. There have been significant declines in concentration and input of sulfate in atmospheric bulk deposition, and in concentration and output of sulfate in stream water since 1964. These changes are strongly correlated with concurrent decreases in emissions of sulfur dioxide from the source area for the Hubbard Brook Experimental Forest. Gross outputs of sulfate in stream water consistently exceeded inputs in bulk deposition and were positively and significantly related to annual precipitation and streamflow. Many other aspects of the biogeochemistry of sulfur were summarized. Understanding the factors regulating the concentrations of basic cations in soils and surface waters is critical if rates of recovery are to be predicted in response to decreases in acidic deposition. Using a
dynamic simulation model (PnET-BGC), we evaluated the extent to which atmospheric deposition of strong acids and associated leaching by strong anions, atmospheric deposition of basic cations through changes in emissions of particulate matter, and historical forest cutting have influenced soil pools of exchangeable basic cations and the acid-base status of stream water at the Hubbard Brook Experimental Forest, New Hampshire. Simulation results indicate that the combination of these factors has resulted in changes in the percent soil base saturation, and stream pH and acid neutralizing capacity from pre-industrial estimates of 20%, 6.3 and 45 ueq L-1, respectively, to current values of 10%, 5.0 and -5 ueq L-1, respectively. These current values fall within the critical thresholds at which forest vegetation and aquatic biota are at risk from soil and surface water acidification due to acidic deposition.
Impacts
Improved understanding of the biogeochemistry of sulfur is critical to understanding the effects of acidic deposition on forest and associated aquatic ecosystems in the Northeast. Reductions in sulfur dioxide emissions and resulting reductions in deposition of sulfate have resulted in reduced concentrations of sulfate in stream water. However, internal processes of sulfur accumulation in soils and subsequent release over time, combined with depletion of base cations will delay ecosystem recovery, even with further reductions in sulfur dioxide emissions.
Publications
- Driscoll, C.T.; Whitall, D.; Aber, J.; Boyer, E.; Castro, M.; Cronan, C.; Goodale, C.; Groffman, P.; Hopkinson, C.; Lambert, K.; Lawrence, G.; Ollinger, S. 2003. Nitrogen pollution in the northeastern United States: sources, effects and management options. BioScience. 53: 357-374.
- Gbondo-Tugbawa, S.S.; Driscoll, C.T. 2003. Factors controlling long-term changes in soil pools of exchangeable basic cations and stream acid neutralizing capacity in a northern hardwood forest ecosystem. Biogeochemistry. 63:161-185.
- Likens, G.E.; Driscoll, C.T.; Buso, D.C.; Mitchell, M.J.; Lovett, G.M.; Bailey, S.W.; Siccama, T.G.; Reiners, W.A.; Alewell, C. 2002. The biogeochemistry of sulfur at Hubbard Brook. Biogeochemistry. 60:235-316.
- Schwarz, P.A.; Fahey, T.J.; McCullock, C.E. 2003. Factors controlling spatial variation of tree species abundance in a forested landscape. Ecology. 84(7): 1862-1878.
- Venterea, R.T.; Lovett, G.M.; Groffman, P.M.; Schwarz, P.A.. 2003. Landscape patterns of net nitrification in a northern hardwood-conifer forest. Soil Science Society of America Journal. 67: 527-539.
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Progress 10/01/01 to 09/30/02
Outputs
Anthropogenic S emissions have been declining in eastern North America since the early 1970s. Declines in atmospheric S deposition have resulted in decreases in concentrations and fluxes of SO42- in precipitation and drainage waters. Recent S mass balance studies have shown that the outflow of SO42- in drainage waters greatly exceeds current S inputs from atmospheric deposition. Identifying the S source(s) which contribute(s) to the discrepancy in watershed S budgets is a major concern to scientists and policy makers because of the need to better understand the rate and spatial extent of recovery from acidic deposition. Results from S mass balances combined with model calculations and isotopic analyses of SO42- in precipitation and drainage waters at the Hubbard Brook Experimental Forest in New Hampshire suggest that this discrepancy cannot be explained by either underestimates of dry deposited S or desorption of previously stored SO42-. Isotopic results suggest that
the excess S may be at least partially derived from net mineralization of organic S as well as the weathering of S-bearing minerals. In another study, a simulation model was developed to determine the response of forest ecosystems to acidic deposition. Application of this model to a watershed in Hubbard Brook Experimental Forest in New Hampshire indicated that losses of buffering capacity due to 50 years of acid deposition greatly extend the time it will take the ecosystem to recover, even with greater-than-expected reductions in acidic deposition.
Impacts
Improved understanding of the biogeochemistry of sulfur and development of simulation models contribute to the development of national policy on air pollution control and management.
Publications
- Blum, Joel D.; Klaue, Andrea; Nezat, Carmen A.; Driscoll, Charles T.; Johnson, Chris E.; Siccama, Thomas G.; Eagar, Christopher; Fahey, Timothy J.; Likens, Gene E. 2002. Mycorhizal weathering of apatite as an important calcium source in base-poor forest ecosystems. Nature. 417: 729-731.
- Federer, C.A. 2001. Case 2tudy 2: effects of warming on snow at the Hubbard Brook Experimental Forest. In: New England regional assessment group, preparing for a changing climate: the potential consequences of climate variability and change. Durham, NH: University of New Hampshire: 58-61.
- Likens, Gene E.; Buso, Donald C.; Hornbeck, James W. 2002. Variation in chemistry of stream water and bulk deposition across the Hubbard Brook Valley, New Hampshire, USA. Verhandlungen International Verein Limnology. 28: 402-409.
- Mitchell, M.J.; Mayer, B.; Bailey, S.W.; Hornbeck, J.W.; Alewell, C.; Driscoll, C.T. 2001. Use of stable isotope ratios for evaluating sulfur sources and losses at the Hubbard Brook Experimental Forest. Water, Air, and Soil Pollution. 130: 75-86.
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Progress 11/16/96 to 11/16/01
Outputs
OUTPUTS: The Hubbard Brook Experimental Forest was established 50 years ago by the U.S. Forest Service to gather hydrometeorologic information. Since that time the research program has expanded to include many facets of applied ecosystem level research. Since 1988, work unit scientists have been actively involved in the National Science Foundation's Long-Term Ecological Research (LTER) network. Hubbard Brook is one of 26 sites in the network that collectively represent diverse ecosystems and research emphases. In addition to the LTER program, the work unit participates in a number of national data collection networks such as the Environmental Protection Agency's Clean Air Status and Trends Network (CASTNET), the Natural Resources Conservation Service's Soil Climate and Analysis Network (SCAN), and the National Atmospheric Deposition Program (NADP). The work unit will continue its participation in the Organization of Biological Field Stations (OBFS) and will operate Hubbard Brook as a Terrestrial Ecosystem Monitoring Site in the international Global Terrestrial Observing System (GTOS) initiated by the World Meteorological Organization and as a Biosphere Reserve as part of the United Nation's Scientific, Educational, and Cultural Organization's Program. This work unit is strongly involved in outreach and education. Scientists and staff present information on research results from the Hubbard Brook Experimental Forest to many visitors (about 600/yr) including scientists (foreign and domestic), administrators, legislators, managers, practicing foresters, conservation groups, students (college, primary schools) and the general public. The work unit is also responsible for the archiving and retrieval of long-term data sets for the Hubbard Brook Ecosystem Study. The unit's data manager collects and stores data files and documentation from cooperators, makes them available to other Hubbard Brook scientists and the general public, and oversees the Hubbard Brook Ecosystem Study World Wide Web site, which provides access to the long-term datasets as well as other information about the HBES. The work unit also maintains the physical sample archive located at HBEF. This repository contains nearly 40,000 samples (e.g. soil, water, rocks vegetation, tree cores) collected at Hubbard Brook since its inception. PARTICIPANTS: Amey Bailey, USFS; Don Mower, USFS; Ian Halm, USFS; Jane Hislop, USFS; Jim Hornbeck, USFS retired; Ralph Perron, USFS; Robert Smith, USFS; Wayne Martin, USFS retired; Bill Parton - Natural Resource Ecology Laboratory, CSU; Claus Beier - RISO National Laboratory, DK; Diane Pataki - University of Utah; Doug Fox - NCAR; Gary Lovett - Institute of Ecosystem Studies ; Gene Likens - Institute of Ecosystem Studies; Gus Shaver - Marine Biological Laboratory; Ian DeMerchant, - Canadian Forest Service; Ivan Fernandez - University of Maine; Jack Cosby - University of Viginia; Jessica Gurevitch SUNY Stoneybrook; Joel Blum - University of Michigan ; Lou Pitelka - Appalachian Environmental Laboratory; Mary Beth Adams - FS; Michael Loik - UC-Santa Cruz; Pep Canadel - CSIRO; Peter Groffman - Institute of Ecosystem Studies; Rich Norby - Oak Ridge National Laboratory; Sara Duke ARS; Steve Kahl - University of Maine; Steve Norton - University of Maine; Thomas Hall - State of Pennsylvania; Tim Fahey - Cornell University; Tom Siccama - Yale University; Yiqi Luo - University of Oklahoma.; Charley Driscoll - Syracuse University; TARGET AUDIENCES: Scientists, national policy makers, and natural resource managers PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The Hubbard Brook Experimental Forest was established 50 years ago by the U.S. Forest Service to gather hydrometeorologic information. Since that time the research program has expanded to include many facets of applied ecosystem level research. For the past 41 years we have cooperated in the collaborative Hubbard Brook Ecosystem Study (HBES) with many educational institutions, federal and state agencies, private foundations, and groups from other countries. The long-term monitoring of baseline forest parameters include: precipitation quantity and chemistry, streamflow quantity and chemistry, physical and chemical characteristics of soil and soil solution, meteorological parameters, and vegetative characteristics and growth. To test new hypotheses, we used the small watershed approach, which was pioneered at Hubbard Brook and uses experimentally treated watersheds to examine biogeochemical processes. This approach has been applied in a whole watershed calcium addition. The goal of this research is to evaluate the role of calcium supply in regulating the structure and function of base-poor forest and aquatic ecosystems. In addition to watershed studies, recent research at Hubbard Brook has been initiated at multiple scales, ranging from small plots to regional analyses. Within the last 5 years there has been a major effort to characterize vegetation and streamwater chemistry across the entire Hubbard Brook Valley. A network of valley-wide permanent plots was established and streamwater chemistry has been evaluated up every stream channel in the valley. In addition to these studies, project scientists have participated in the development of monographs that focus on individual elements (e.g. carbon, sulfur, calcium). These comprehensive peer-reviewed manuscripts summarize vast amounts of data and information based on research conducted at Hubbard Brook.
Publications
- Campbell, J. L.; Driscoll, C. T.; Eagar, C.; Likens, G. E.; Siccama, T. G.; Johnson, C. E.; Fahey, T. J.; Hamburg, S. P.; Holmes, R. T.; Bailey, A. S.; Buso, D. C. 2007. Long-term trends from ecosystem research at the Hubbard Brook Experimental Forest. Gen. Tech. Rep. NRS-17. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 41p.
- Luo,Yiqi; Gerten, Dieter; le Maire, Guerric; Parton, William; Weng, Ensheng; , Zhou, Xuhui; Keough, Cindy; Beier, Claus; Cramer, Wolfgang; Dukes, Jeff; Emmett, Bridgett; Hanson, Paul; Knapp, Alan; Linder, Sune; Nepstad, Daniel; Rustad, Lindsey. 2008. Modeled interactive effects of precipitation, temperature and CO2 on ecosystem carbon and water dynamics in different climatic zones. Global Change Biology. 14: 1986-1999.
- Mitchell, Myron J.; Bailey, Scott W.; Shanley, James B.; Mayer, Bernhard. 2008. Evaluating sulfur dynamics during storm events for three watersheds in the northeastern USA: a combined hydrological, chemical and isotopic approach. Hydrological Processes. 22:4023-4034. Tetzlaff, D.; McDonnell, J.J.; Uhlenbrook, S.; McGuire, K.J.; Bogaart, P.; Naef, F.; Baird, A.J.; Dunn, S.M.; Soulsby, C. 2008. Conceptualizing catchment processes: simply complex Hydrological Processes. 22(11): DOI: 10.1002/hyp.7069.
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