LUQ LTER DATA SETS DOCUMENTATION FORM

ON-LINE VERSION

A DATA SET is a series of observations collected by the same methodology. Each data set should have documentation sufficient for someone unfamiliar with the research to replicate the study. Data sets may be broken into subsets (data files) that are discrete in space and time, in that order. The documentation for a data set should include all spatial and temporal subdivisions of the data.

(Data, Abstract, Methods, Variables)

NOTES:

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DATA SET IDENTIFIER: Chemistry of rainfall, throughfall, and stream water from El Verde and Bisley Verde and Bisley stations

PROJECT TITLE: Precipitation and Stream Chemistry

PROJECT DESCRIPTION: Soil organic matter content (SOM) and C:N ratios of the litter (Weaver et al. 1973, Zou et al. 1995) and SOM (Silver et al. 1999) increase with elevation and are expected to influence stream chemistry (Aitkenhead & McDowell 2000). Linking stream chemistry to characteristics of watershed soils and vegetation (litter quality, soil C:N, soil C and N standing stocks) can be done within the timeframe of the current funding request.

Rain, throughfall, and stream water are collected weekly at 18 LEF sites. These data cover the period from 1988 onwards. Earlier rain and stream water chemistry data are in the files from William McDowell.

LTER CORE AREAS: Annotate all that apply (See online list)

LEF LTER 1 RESEARCH TOPIC: (Annotate all that apply) (See online list)

We define a data file as a component of a data set. A data set can have only one data file or more. Basically, different data files have different data structures or format .
DATA SET FILES (SUBSETS):

RESEARCH LOCATION: Streams and rain collectors described and listed in the site's description and data files.

INVESTIGATORS:

SOURCE OF FUNDING (SPONSOR): NSF-LTER

DATA SET ABSTRACT: Rain, throughfall, and stream water are collected weekly at the LEF sites listed below. These data sets begin as early as 1983; LTER sampling began in 1988.

Rain and throughfall samples are the total catch for the week, and are exposed to field conditions for that time. No event sampling is conducted on a routine basis. Stream water samples are grab samples taken from the water/air interface at stream channel center on the sampling day (usually Tuesdays). Rain samples from WDEV are wet only from an automatically-closing collector that prevents any dry deposition (Aerochem Metrics NADP collector). RCEV and RCB are bulk or always-open collectors that receive dry deposition by sedimentation.

A continuous record of stream stage (height) is recorded by a datalogger at all ongoing stream sampling sites. Average daily streamflows are available from the USGS and at other locations (Hydrology and Meteorology) on this site.

All samples are measured for pH and conductivity, and then filtered (pre-combusted Whatman GF/F glass fiber filter) prior to further analysis. From 1983-1994 samples were cooled and returned to the San Juan chemistry laboratory for analysis. During those years, samples for NH₄ and NO₃ analyses were refrigerated continuously until analysis. Subsamples for NH₄ analysis were also preserved with 1 molar HCl. From 1994 on, samples for NH₄ and NO₃ were frozen until analysis, were not acidified, and all analyses were conducted at the University of New Hampshire.

Rain, Throughfall, and Stream water Sampling Sites
Descriptions of LTER LUQ rain, throughfall, and stream water weekly sample chemistry data from 1988 onwards. Chemical concentrations are recorded as mg/L or mg/L as appropriate. Values below detection limits are recorded as 1/2 the detection limit.

DATA SET METHODS:
Analytical Techniques
pH - Electrometric with combination electrode
Conductivity - Conductivity bridge
Cl - up to 1989 by automated colorimetric analysis (thiocyanate); after 1989 by liquid chromatography with conductivity detection
NO3-N - up to 1989 by automated colorimetric analysis (Cd-Cu reduction); after 1989 by liquid chromatography with UV or conductivity detection
SO4-S - Liquid chromatography, conductivity detection
Na, K, Mg, and Ca - up to 1994 by atomic absorption spectroscopy; after 1994 by ion chromatography with conductivity detection
NH4-N - automated colorimetric analysis (phenolhypochlorite)
PO4-P - automated colorimetric analysis (molybdate blue)
DOC - up to 1998 by persulfate oxidation (McDowell et al. 1997); after 1998 by high temperature catalytic oxidation
DIC - by syringe stripping and infrared spectroscopy (Stainton 1973).
TDN - prior to 1998 by persulfate oxidation and automated colorimetric analysis; after 1998 by high temperature catalytic oxidation with chemiluminescent detection
TDP - by persulfate digestion followed by automated colorimetric analysis
SiO2 - automated colorimetric analysis (molybdate blue)
DON - by difference (TDN - NO3-N - NH4-N)

Table 1. Data Abbreviations, Detection Limits, and Units of Measure

REFERENCES:
McDowell, W.H., J.J. Cole, and C.T. Driscoll. 1987. Simplified version of the ampoule-persulfate method for determination of dissolved organic carbon. Can. J. Fish. Aquat. Sci. 44:214-218.

Stainton, M.P. 1973. A syringe gas-stripping procedure for gas chromatographic determination of dissolved inorganic and organic carbon in fresh water and carbonates in sediments. J. Fish. Res. Bd. Can. 30:1441-1445.

CROSS-REFERENCES (other data sets related to this one):

SAMPLE LOCATION: ITES, Chemistry Laboratory

STORAGE SITES(of data files): ITES, Data Manager's File DM-001 , Drawer #2

INVESTIGATOR'S ASSIGNED KEYWORDS: Biogeochemical cycles, nutrient input/output relationships, ammonium, nitrate, sulfate, chloride, potassium, sodium, calcium, magnesium

LEF LTER OFFICIAL KEYWORDS (See table): BISLEY GAPS, EL VERDE, Q MAMEYES, Q PRIETA, Q TORONJA, Q ICACOS, RAIN, RIVER, BIOGEOCHEMICAL CYCLES, CATIONS AND ANIONS, NITROGEN, DISCHARGE, PEER REVIEWED JOURNAL

PUBLICATIONS:
McDowell, W.H., C. Gines-Sanchez, C.E. Asbury, and C.R. Ramos-Perez. 1990. Influence of sea salt aerosols and long-range transport on precipitation chemistry at El Verde, Puerto Rico. Atmospheric Environment 24A:2813-2821.

McDowell, W.H. and C.E. Asbury. 1994. Export of carbon, nitrogen, and major ions from three tropical montane watersheds. Limnology and Oceanography 39:111-125.

Schaefer, D.A., W.H. McDowell, F.N. Scatena, and C.E. Asbury. 2000. Effects of hurricane disturbance on stream water concentrations and fluxes in eight watersheds of the Luquillo Experimental Forest, Puerto Rico. J. Tropical Ecology 16:189-207.

DISSEMINATION:

RESTRICTED ___ UNRESTRICTED _X__

REASONS TO RESTRICT DATA IN THIS DATA SET BEYOND ITS TWO YEAR POLICY PERIOD*:

*WILL HAVE TO BE APPROVED BY AT LEAST ONE LUQ LTER PRINCIPAL INVESTIGATORS: N. Brokaw, J. ZIMMERMAN, A. LUGO

FILING

_X_ "File" copy only:Data Management will only file an electronic copy of the data file and its documentation 
___ " Enter" data on-line:Data Management will be in charge of entering the data on computer files (Contact Eda C. Meléndez)

SITES DESCRIPTIONS:
The study site was the Luquillo Experimental Forest on the eastern end of Puerto Rico (18 15'N, 65 50'W). The Luquillo Experimental Forest is synonymous with the Caribbean National Forest and has been administered by the U.S. Forest Service for ~70 yrs. Elevation ranges from 200 to 1,000m. The plan community is dominated by tabonuco (Dacryodes excelsa) forest type at elevations of 200-600m adn the colorado (Cyrilla racemiflora) forest type at elevations of 600-750 m. On ridges and peaks above 750 m, vegetation consists of short-statured elfin forest. Palms (most commonly Prestoea montana) are found throughout the forest but are especially common along streams channels and in poorly drained areas. Human disturbance, consisting of small farms and selective tree harvesting (mostly at lower elevations), preceded Forest Service administration. Scattered plantation forests have been established since designation of the area as an experimental forest (Brown et al. 1983).

Precipitation ranges from 250 to >500 cm yr^-1 in the Luquillo Forest area and increases with elevation. Precipitation peaks in May and from August to November (McDowell and Estrada-Pinto 1988). Hurricanes and tropical depressions produce individual rainfall events that are highly unpredictable and very intense, and hurricanes are thought to play a major role in structuring plant community dynamics (Brown et al. 1983).

The following table summarizes the features of the studied watersheds:

Table 2. Characteristics of three of the long-term study watersheds

Geographical positional system (GPS) Coordinates for each location:

VARIABLES (ATTRIBUTES):

VARIABLES (ATTRIBUTES):

Note: This unit was display as "feet" until April 10, 2008. This should be corrected as "meter";this was a typo not a change of measuring method.

VARIABLES (ATTRIBUTES):

VARIABLES (ATTRIBUTES):

VARIABLES (ATTRIBUTES):

COMPUTATIONAL METHODS:

FOR DATA MANAGER USE ONLY

DATE OF LAST REVIEW: