Hubbard Brook Experimental Forest

Palmer SM, Driscoll CT, Johnson CE. 2004. Long-term trends in soil solution and stream water chemistry at the Hubbard Brook Experimental Forest relationship with landscape position. Biogeochemistry 68(l) 51-70. 

In the USA, two focal points for biogeochemical research have been the forest catchment ecosystems at Hubbard Brook Experimental forest in the White Mountains of... 

The input of airborne lead to the Forest ecosystems has been studied at the Hubbard Brook Experimental Forest in New Hampshire. The small catchment approach has been used to study the lead biogeochemical cycle since 1963 (Likens et al., 1977 Driscoll et al., 1994). By monitoring precipitation inputs and stream output from small watersheds that are essentially free of deep seepage, it is possible to constmct accurate lead mass balance. The detailed study of soil and soil solution chemistry and forest floor and vegetation dynamics supplemented the deposition monitoring. 

Figure 24. Biogeochemical mass balance of lead in Forest ecosystems of Hubbard Brook Experimental Forest, USA (Driscoll et al., 1994).

Figure 25. Temporal pattern of the concentration of Pb in the bio geochemical reference watershed at the Hubbard Brook Experimental Forest, NH, USA (a) bulk precipitation (b) the forest floor (c) stream water (after Driscoll etal., 1994).

Driscoll, C., Gbondo-Tugbawa, S., Aber, J., Likens, G., Buso, D. (1998). The long-term changes in precipitation and stream chemistry at the Hubbard Brook experimental forest, NH measurements and model calculations. In NADP Technical committee meeting. Abstracts of papers, p 16... 

Findlay, S., K. Howe, and D. Fontvieille. 1993. Bacterial-algal relationships in streams of the Hubbard Brook experimental forest. Ecology 74 2326-2336. 

Fisher DW, Gambell AW, Likens GE, et al. 1968. Atmospheric contributions to water quality of streams in the Hubbard Brook Experimental Forest, New Hampshire. Water Resour Res 4 1115-1126. 

Isotope ratios have been used with some success in the past to determine the importance of gas phase (Equation 4) verses aqueous phase (Equations 2A,2B,2C) oxidation of SO2. Saltzman et al. (24) compared the S34S values for SO2 and sulfate from samples collected from Hubbard Brook Experimental Forest (HBEF) in the non-urban northeastern US. They found discriminations which were intermediate to those expected for the individual oxidation mechanisms and suggested that both gas and aqueous phase oxidation were important. Newman (50) found that 6 S values for SO2 in the plume of an oil fired power plant decreased with distance (and time) from the stack which they attributed to equilibrium isotope effects. 

Figure 5. Comparison between EUS S02 anc NOx emissions and annual weighted concentrations of SO -, NO3, and NH in bulk deposition at the Hubbard Brook Experimental Forest from 1964 to 1977. Line through emissions is drawn through estimates each five year period from 1965. (From Hidy, 8).

Figure 3 Long-term declines in sulfate concentrations mitigate the mobilization of aluminium in soil solutions and stream water in the Hubbard Brook Experimental Forest, New Hampshire, USAf a-c, annual volume-weighted concentrations of a, inorganic monomeric aluminium (Ah) b, organic monomeric aluminium (Af) and c, sulfate (SO/ ) in mineral soil solutions at 750 m (%) and 730 m (O), and in stream water (triangles)...

Johnson N. M., Driscoll C. T., Eaton J. S., Likens G. E., and McDowell W. H. (1981) Acid rain, dissolved aluminum and chemical weathering at the Hubbard Brook Experimental Forest, New Hampshire. Geochim. Cosmoshim. Acta 45, 1421-1437. 

Long-term studies of the nutrient balance at the Hubbard Brook Experimental Forest show that much of the S04 entering via atmospheric deposition passes through vegetation and microbial biomass before being released to the soil solution and stream water. Gaseous emission loss of sulfur is probably small. The residence time for S in the soil was determined to be 9 yr (Likens et ah, 2002). 

Lawrence G. B., Fuller R. D., and Driscoll C. T. (1987) Release of aluminum following whole-tree harvesting at the hubbard brook experimental forest. New Hampshire, USA. J. Environ. Qual. 16, 383-390. 

The study of SOM, and dissolved organic carbon (DOC) in soil solutions and stream samples in clear-cut and uncut sites at the Hubbard Brook Experimental Forest in New Hampshire using DOC fractionation techniques and solid-state C NMR has been presented. 

Hall, R.J., Likens G.E., Fiance S. B. and Hendrey, G.R. Experimental acidification of a stream in the Hubbard Brook Experimental Forest, New Hampshire. Ecology 1980, 61, 976-989. 

Fahey, T. J., and Hughes, J. W. (1994). Fine root dynamics in a northern hardwood forest ecosystem, Hubbard Brook Experimental Forest, NH. J. Ecol. 82, 533-548. 

Biogeochemical cycles of individual elements, including nitrogen, have been intensively studied at the Hubbard Brook experimental Forest (HBEF) in New Hampshire, USA, since 1963, pioneering the use of the small catchment concept for understanding biogeochemical processes in the ecosystems (see Likens etal, 1977). The numerous... 

Fig. 8-11. Frequency distribution of pH values observed in hydrometeors. (A) Ernst (1938), 47 bulk rain samples collected in Bad Reinerz, combined with 80 samples showing a similar distribution collected in Oberschreiberhau (both locations in upper Silesia, central Europe), 1937-1938. (B) Mrose (1966), 206 bulk rain samples collected at Dresden-Wahnsdorf (German Democratic Republic), 1957-1964. (C) Esmen and Fergus (1976), about 200 individual rain drops collected during a single rainstorm in Delaware, 1974. (D, E) Likens etal. (1984), weekly samples of bulk rainwater collected at Hubbard Brook Experimental Forest Station, New Hampshire, D 1964-1968, E 1975-1979. (F) Falconer and Falconer (1980), 824 measurements of cloud water collected continuously at Whiteface Mountain, New York, 1977.

The consensus in scientific understanding at the time was largely due to having a few locations, such as the Hubbard Brook Experimental Forest, described in detail in subsequent chapters, where there were high quality time series of both rainfall pH and surface water acidity, and where very careful experimentation had been done to understand the processes involved. Such high quality time series were of enormous value in understanding the processes by which acid deposition was affecting surface waters, soils, and ultimately forest ecosystems. 

Figure 3.2. Annual emissions of sulfur dioxide and nitrogen oxides for the source area of the Hubbard Brook Experimental Forest. The source area was determined by 24-hour back trajectory analysis. Shown are emissions from both U.S. and Canadian sources...

Figure 3.3. Annual volume-weighted sulfate, nitrate, and ammonium concentrations and pH in bulk and wet deposition at the Hubbard Brook Experimental Forest, New Hampshire 1963-2000...

The Hubbard Brook Experimental Forest is a long-term ecological research site established by the U.S. Department of Agriculture Forest Service in the White Mountains of New Hampshire to investigate the structure and function of forest and aquatic ecosystems, and their response to disturbance (Likens and Bormann 1995 Groffman et al. 2004). Hubbard Brook was the site where acidic deposition was first reported in North America (Likens et al. 1972). Hubbard Brook receives elevated inputs of acidic deposition and the forest ecosystem is very sensitive to these inputs. There have been long-term measurements and studies of acidic deposition and its effects on forests and streams at Hubbard Brook (Likens et al. 1996 Driscoll et al. 2001). 

Figure 3.9. Annual volume-weighted stream water sulfate, nitrate, calcium concentrations, pH, and concentrations of total (Aim) and organic dissolved aluminum (Alo) at the reference watershed of the Hubbard Brook Experimental Forest from 1963-2000. Note that dissolved inorganic aluminum is the difference between total and organic dissolved aluminum...

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