Hubbard Brook Experimental Forest Throughfall Data, 1989-1992
TITLE
Hubbard Brook Experimental Forest Throughfall Data, 1989-1992
PRINCIPAL INVESTIGATOR(s)
Gary M. Lovett
Cary Institute of Ecosystem Studies
Box AB
Millbrook, NY 12545
USA
OTHERS INVOLVED
Scott S. Nolan
Charles T. Driscoll
Timothy J. Fahey
ABSTRACT:
Throughfall was collected during the growing season (1 June - 30 September) from sites on or near Watershed 5 (1989, 1990, 1992) and Watershed 6 (1989 - 1992). Samples were analysed for cations, anions, pH and Total Organic Carbon (TOC).
KEYWORD SET: Hubbard Brook Ecosystem Study LTER
aluminum, ammonium, calcium, chemistry, chloride, forests, HBEF throughfall study, HBEF Watershed 5, HBEF Watershed 6, HBR, Hubbard Brook LTER, magnesium, nitrate, nutrient cycling, pH, phosphate, potassium, precipitation, rain, silica, sodium, sulfate, throughfall, total organic carbon, watershed.
KEYWORD SET: LTER Core Research Areas
inorganic nutrients, organic matter.
BEGIN DATE
1989
END DATE
1992
LOCATION
Watershed 5 Site A
West bounding coordinate: -71.739375
East bounding coordinate: -71.731253
North bounding coordinate: 43.957167
South bounding coordinate: 43.948942
Elevation
Minimum: 525
Maximum: 525
(Unit: meter)
Watershed 5 Site B
West bounding coordinate: -71.739375
East bounding coordinate: -71.731253
North bounding coordinate: 43.957167
South bounding coordinate: 43.948942
Elevation
Minimum: 570
Maximum: 570
(Unit: meter)
Watershed 5 Site C
West bounding coordinate: -71.739375
East bounding coordinate: -71.731253
North bounding coordinate: 43.957167
South bounding coordinate: 43.948942
Elevation
Minimum: 685
Maximum: 685
(Unit: meter)
Watershed 5 Site D
West bounding coordinate: -71.739375
East bounding coordinate: -71.731253
North bounding coordinate: 43.957167
South bounding coordinate: 43.948942
Elevation
Minimum: 750
Maximum: 750
(Unit: meter)
Watershed 6 Site A
West bounding coordinate: -71.742990
East bounding coordinate: -71.735175
North bounding coordinate: 43.957070
South bounding coordinate: 43.949996
Elevation
Minimum: 530
Maximum: 530
(Unit: meter)
Watershed 6 Site B
West bounding coordinate: -71.742990
East bounding coordinate: -71.735175
North bounding coordinate: 43.957070
South bounding coordinate: 43.949996
Elevation
Minimum: 605
Maximum: 605
(Unit: meter)
Watershed 6 Site C
West bounding coordinate: -71.742990
East bounding coordinate: -71.735175
North bounding coordinate: 43.957070
South bounding coordinate: 43.949996
Elevation
Minimum: 705
Maximum: 705
(Unit: meter)
Watershed 6 Site D
West bounding coordinate: -71.742990
East bounding coordinate: -71.735175
North bounding coordinate: 43.957070
South bounding coordinate: 43.949996
Elevation
Minimum: 775
Maximum: 775
(Unit: meter)
SAMPLING DESIGN
Study areas were on or near watersheds 5 and 6. The study area spans the elevational range 500-800 m. Watershed 6 (13 ha) and adjacent land to the west is covered by mature northern hardwood forest in which the dominant canopy tree species are sugar maple (Acer saccharum Marsh), American beech (Fagus grandifolia Ehrh.), and yellow birch (Betula allegheniensis Britt.) with some white ash (Fraxinus americana L.) on the lower slopes. Canopy height is generally about 20-25 m, and epiphyte cover is negligible. The upper 20% of the hillslope is covered by a spruce-fir-birch forest type comprised of red spruce (Picea rubens Sarg.), balsam fir (Abies balsamea (L.) Miller) and paper birch (Betula papyrifera Marsh.). Canopy heights in this zone are generally < 20m and epiphytic lichens are present on larger spruces and firs.
On watershed 5 (22 ha), which is immediately to the east of watershed 6, all trees > 10 cm dbh were harvested in 1983-84 and a regenerating forest was present during this study. These 6-10 year old stands are dominated by pin cherry (Prunus pennsylvanica L.), usually with an understory of beech, maple, and yellow birch. In 1992, the generating forest had attained a height of about 20 m in the lower parts of the watershed but only about 1-2 m near the ridge because of thin soils, exposure to wind, and severe browsing by moose.
Throughfall was collected at four sites in the mature forest during the growing seasons (1 June - 30 September) of 1989 - 1992 (Table 1). Three of the sites (6 A, B, and C) were in the northern hardwood forest type, and the fourth (6D) had a sparse paper birch overstory and an understory of spruce and fir. Although these sites are not in watershed 6 (which is maintained as a reference watershed with minimal access) they are adjacent to it and are representative of its vegetation. In 1989, 1990, and 1992 throughfall was also collected at four sites in the regenerating forest of watershed 5 (sites 5A, B, C and D). Incident bulk precipitation was collected in three clearings at 550, 650, and 780 m.
Each throughfall collector consisted of 20 cm diameter polyethylene funnel mounted about 1 m above the ground on a narrow wooden stand; the funnel drained directly into a clear polyethylene bag. A plug of fibrous polyester was placed in the stem of the funnel to filter coarse debris. Six such collectors were placed randomly at each site, and throughfall from the six collectors was pooled into a single sample for the site.
Samples were usually collected within 24 hrs after the end of a rain event, although during periods of low personnel availability samples were collected at longer intervals, but at least weekly. For this study, a precipitation event was defined as a rainfall sufficient to produce measurable throughfall, separated from other rainfall periods by at least a 6 h dry period. Of the 51 collections made during the study period, 21 represented single precipitation events and 30 included multiple events. At the time of sample collection, clean bags were installed in each collector and the polyester filter was changed. The throughfall from all collectors at each site was pooled in the field, the volume was measured with a graduated cylinder, and a sample was brought back to the laboratory. An aliquot was allowed to come to room temperature and pH was measured with a glass electrode. Another aliquot of the sample, for analysis of NH4+ and NO3-, was preserved with 100 uL of chloroform per 100mL of sample, and a third aliquot for other analyses was not preserved. All samples were stored in the dark at 4o C until chemical analysis was completed, usually within 6 months.
CALCULATIONS:
The incident precipitation amount and chemistry used in these analyses is the mean of our three open collectors for each collection period. Stemflow was not measured during this study. However, Eaton et al. (1973) measured stemflow in this forest and found that fluxes ranged from 4 - 13% (depending on the element) of throughfall fluxes. Thus the total solution flux to the forest floor in this ecosystem is somewhat higher than the throughfall fluxes reported here. For each site, volume-weighted mean concentrations for each year were multiplied by the appropriate precipitation amounts to calculate fluxes in TF and bulk precipitation.
LABORATORY PROCEDURES
Analysis for NO3-, SO42-, and Cl- were measured with ion chromatography, K+, Na+, Ca2+, and Mg2+ by atomic absorption spectrophotometry (Ca2+ and Mg2+ stabilized by lanthanum addition), and NH4+ by the indophenol blue method on a Technicon autoanalyzer. Total organic carbon (TOC) was measured by infrared detection of CO2 after persulfate digestion, using an Astro 2001 TOC analyzer. Statistical analysis was done in the SAS software system using the REG, ANOVA, and UNIVARIATE procedures (SAS 1987).
REFERENCES
  • Likens, G.E., Driscoll, C.T., Buso, D.C., Siccama, T.G., Johnson, C.E., Ryan, D.F., Lovett, G.M., Fahey, T.J., and Reiners, W.A. 1994. The biogeochemistry of potassium at Hubbard Brook. Biogeochemistry 25:61-125.
  • Likens, G.E., Driscoll, C.T., Buso, D.C., Siccama, T.G., Johnson, C.E., Lovett, G.M., Fahey, T.J., Reiners, W.A., Ryan, D.F., Martin, C.W., and Bailey, S.W. 1998. The biogeochemistry of calcium at Hubbard Brook. Biogeochemistry 41(2):89-173.
  • Lovett, G.M., Nolan, S.S., Driscoll, C.T., and Fahey, T.J. 1996. Factors regulating throughfall flux in a New Hampshire forested landscape. Canadian Jounal of Forest Research 12:2145-2151.
DATA ACCESS GUIDELINES
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CONTACT PERSON

Information Manager, Hubbard Brook LTER
234 Mirror Lake Road
North Woodstock, NH 03262
USA

Phone: (603) 726-8902
Email: hbr-im@lternet.edu

Data file: through-samp.txt
Description: Characteristics of sites used for throughfall sampling
Notes on Data: The data is physically located at the USDA Forest Service, Durham, NH and was last updated in October 1997.
ColumnVariableDescriptionUnitsCoded?Missing value label
1WatershedThe identification number of the current watershednoneynone
2SiteThe identification letter of the current sitenoneynone
3ElevationTopographical elevation of the current sitemeternnone
4VegetationIdentification codes for various vegetation types encountered in the current sitenoneynone
5Years sampledThe individual year or range of years during which sampling occurrednoneynone

CODES

Variable: Watershed
Code
Description
5
Watershed 5
6
Watershed 6
Variable: Site
Code
Description
A
Site area A
B
Site area B
C
Site area C
D
Site area D
Variable: Vegetation
Code
Description
PC
Pin cherry
PB
Paper birch
NH
Northern hardwood
S
Red spruce
F
Balsam fir
Variable: Years sampled
Description:
Years that samples were collected between 1989 - 1992

Data file: through1.txt
Description: The file through1.txt contains precipitation amount (cm) and volume-weighted mean concentrations (umol/L, except TOC in mg C/L) of solutes in bulk precipitation ("BP") and throughfall at the sampling sites. Sites are listed in Table 1. Means and standard deviations across sampling years are shown; n=3 years for watershed 5 sites, n=4 years for watershed 6 sites.
ColumnVariableDescriptionUnitsCoded?Missing value label
1SiteThe labeled site identification letter and optional BP suffix indicating that the current data point is a bulk precipitation valuenoneynone
2MEAN/STDWhether the current data point is a mean or standard valuenoneynone
3H2O(water) precipitation measurementcentimeternnone
4Cl-concentration of chlorine anionsmicroMolePerLiternnone
5NO3-concentration of nitrate anionsmicroMolePerLiternnone
6SO4 2-concentration of sulfate anionsmicroMolePerLiternnone
7Na+concentration of sodium cationsmicroMolePerLiternnone
8K+concentration of potassium cationsmicroMolePerLiternnone
9Ca 2+concentration of calcium cationsmicroMolePerLiternnone
10Mg 2+concentration of magnesium cationsmicroMolePerLiternnone
11NH4+concentration of ammonium cationsmicroMolePerLiternnone
12H+proton concentrationmicroMolePerLiternnone
13TOCtotal organic carbon concentrationmilligramPerLiternnone

CODES

Variable: Site
Code
Description
5BP
Watershed 5 bulk precipitation
5A
Watershed 5 site A precipitation
5B
Watershed 5 site B precipitation
5C
Watershed 5 site C precipitation
5D
Watershed 5 site D precipitation
6BP
Watershed 6 bulk precipitation
6A
Watershed 6 site A precipitation
6B
Watershed 6 site B precipitation
6C
Watershed 6 site C precipitation
6D
Watershed 6 site D precipitation
Variable: MEAN/STD
Code
Description
MEAN
A mean value
STD
A standard value

Data file: through2.txt
Description: The file through2.txt contains fluxes of solutes in bulk precipitation ("BP") and throughfall at the sampling sites. Sites are listed in Table 1. Mean fluxes (mol/ha, except TOC in kg C/ha) and standard deviations across sampling years are shown.
ColumnVariableDescriptionUnitsCoded?Missing value label
1SiteThe labeled site identification letter and optional BP suffix indicating that the current data point is a bulk precipitation valuenoneynone
2MEAN/STDWhether the current data point is a mean or standard valuenoneynone
3Cl-concentration of chlorine anionsmolePerHectarennone
4NO3-concentration of nitrate anionsmolePerHectarennone
5SO4 2-concentration of sulfate anionsmolePerHectarennone
6Na+concentration of sodium cationsmolePerHectarennone
7K+concentration of potassium cationsmolePerHectarennone
8Ca 2+concentration of calcium cationsmolePerHectarennone
9Mg 2+concentration of magnesium cationsmolePerHectarennone
10NH4+concentration of ammonium cationsmolePerHectarennone
11H+proton concentrationmolePerHectarennone
12TOCtotal organic carbon concentrationkilogramPerHectarennone

CODES

Variable: Site
Code
Description
5BP
Watershed 5 bulk precipitation
5A
Watershed 5 site A precipitation
5B
Watershed 5 site B precipitation
5C
Watershed 5 site C precipitation
5D
Watershed 5 site D precipitation
6BP
Watershed 6 bulk precipitation
6A
Watershed 6 site A precipitation
6B
Watershed 6 site B precipitation
6C
Watershed 6 site C precipitation
6D
Watershed 6 site D precipitation
Variable: MEAN/STD
Code
Description
MEAN
A mean value
STD
A standard value