HF030
Precipitation, soil, and xylem water-isotope data from various pools throughout H.J. Andrews Watershed 10, 2004-2006

CREATOR(S): J. Renée Brooks

PRINCIPAL INVESTIGATOR(S): J. Renée Brooks

ORIGINATOR(S): J. Renée Brooks

OTHER RESEARCHER(S): Rob Coulombe

DATA SET CONTACT PERSON: J. Renée Brooks

METADATA CONTACT: J. Renée Brooks

DATA SET CREDIT:

J. Renee Brooks, Pacific Ecological Systems Division, US EPA.

METADATA CREATION DATE:

18 Nov 2020

MOST RECENT METADATA REVIEW DATE:

26 Aug 2022

PURPOSE:

To sample soil and tree xylem water at several locations across the watershed to capture the variability within the watershed and ultimately correlate the data with catchment geology or other hydrologic indices already established for WS10.

METHODS:

Experimental Design - HF030:

Description: For our spatially intensive sampling, water samples for isotopic analysis were collected at 32 locations next to permanent vegetation plots randomly distributed throughout the watershed covering the range of elevation and aspect. Samples were collected at the beginning of the dry season, 28 June 2004, and once at the end of the dry season, 14 September 2004, and again on 28 August 2005. For our temporally intensive sampling in the autumn of 2006, water samples for isotopic analysis were collected weekly from five of the permanent vegetation plots: two in the upper watershed, north and south aspects; two in the lower watershed, north and south aspect; and a further mid-watershed, south aspect location.

Citation: Brooks, J. R., H. Barnard, R. Coulombe, and J. J. McDonnell. 2010. Ecohydrologic separation of water between trees and streams in a Mediterranean climate. Nature Geoscience 3:100-104

Field Methods - HF030:

Description: For the spatially intensive sampling: At each site, tree water samples were collected from suberized xylem of three trees, which reflects soil water from where the trees are withdrawing water, as trees do not fractionate water during uptake. Soil samples were collected from 5 depths (10, 20, 30, 50 cm and 1 m, if possible) and were divided into two parts, one for isotopic analysis and another for gravimetric soil moisture measurement. In addition, several stream samples were collected at the weir during the day. For the temporally intensive sampling: Xylem samples and soil samples were collected as outlined above, except that soil sampling was limited to 10, 20, and 50 cm depths. In addition, water was collected from low-tension (max 60 kPa of tension was applied) porous-cup lysimeters, (Soil Moisture Equipment Corp.) at 20, 50 and 1m depth when water was present. Precipitation was collected in 5mm increments at both the upper and lower parts of the watershed using passive sequential samplers utilizing the method described in Kennedy et. al (1979). Streamwater was collected hourly during storms and every 4_8 h between storms. Soil volumetric water content was quantified using multi-sensor, frequency domain capacitance probes (EnviroSCAN, Sentek Pty) at 20, 30, 40, 50, 60 and 100 cm depth at 30 min intervals.

Instrumentation: Soil volumetric water content was quantified using multi-sensor, frequency domain capacitance probes (EnviroSCAN, Sentek Pty)

Citation: Kennedy, V. C., Zellweger, G. W. & Avanzino, R. J. 1979. Variation of rain chemistry during storms at two sites in northern California. Wat. Resour. Res. 15, 687702. doi.org/10.1029/WR015i003p00687

Laboratory Methods - HF030:

Description: Samples for Delta-2H (or D2H) and Delta-18O (or D18O) analysis in plant and soil water were collected in glass vials with polyseal cone inserts in the cap and sealed to prevent evaporation. Water was extracted from the plant and soil samples using cryogenic vacuum distillation. Water samples were analyzed for Delta-2H (or D2H) and Delta-18O (or D18O) on an isotope ratio mass spectrometer (Delta plus, Finnigan) interfaced with a high-temperature conversion/elemental analyzer (ThermoQuest Finnigan, all xylem and soil water samples) or a laser absorption water-vapour isotope spectrometer (Model 908-0004, Los Gatos Research, all precipitation and stream water samples) located at the Integrated Stable Isotope Research Facility at the Pacific Ecological Systems Division of the EPA, Corvallis, Oregon. All Delta-2H (or D2H) and Delta-18O (or D18O) values are expressed relative to Vienna Standard Mean Ocean Water (VSMOW)

Instrumentation: Water samples were analyzed for Delta-2H (or D2H) and Delta-18O (or D18O) on an isotope ratio mass spectrometer (Delta plus, Finnigan) interfaced with a high-temperature conversion/elemental analyzer (ThermoQuest Finnigan, all xylem and soil water samples) or a laser absorption water-vapour isotope spectrometer (Model 908-0004, Los Gatos Research, all precipitation and stream water samples) located at the Integrated Stable Isotope Research Facility at the Pacific Ecological Systems Division of the EPA, Corvallis, Oregon.

Permanent Plots - HF030:

Description: Samples were collected just outside Watershed 10 permanent vegetation plots.

Quality Assurance - HF030:

Description: Measurement precision for the high-temperature conversion/elemental analyzer was 1.5 and 0.2 ‰ for Delta-2H (or D2H) and Delta-18O (or D18O), respectively, and for the laser spectrometer, precision was 0.5 and 0.2 ‰ for Delta-2H (or D2H) and Delta-18O (or D18O), respectively based on sample duplicates and standards.

SITE DESCRIPTION:

WS10 is a 10 hectare watershed that was 100% clearcut in 1975 and is forested with approximately 30-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Elevation in WS10 ranges between 425 and 700m. Soils within this watershed are gravelly clay loams for the surface with lower layers consisting of gravelly silty clay or clay loams with textures averaging 27, 35 and 38% sand, silt and clay, respectively. Porosity is approximately 60%. Data have been collected on streamwater discharge, climate, stream chemistry and vegetation since before clearcutting.

Samples from 2004-2005 were collected around 32 permanent vegetation plots located within WS10. In 2006, 5 plots were selected for more temporally intensive sampling: 7, 15, 22, 25 and 34.

TAXONOMIC SYSTEM:

ITIS, the Integrated Taxonomic Information System

GEOGRAPHIC EXTENT:

Watershed 10 within the H. J. Andrews Experimental Forest

ELEVATION_MINIMUM (meters):

478

ELEVATION_MAXIMUM (meters):

659

MEASUREMENT FREQUENCY:

Variable by year

PROGRESS DESCRIPTION:

Complete

UPDATE FREQUENCY DESCRIPTION:

notPlanned

CURRENTNESS REFERENCE:

Ground condition