MV003
Throughfall and Isotopic Ratios on WS1 at the Andrews Experimental Forest, 2010-2011

CREATOR(S): Barbara J Bond, Scott Thomas Allen

PRINCIPAL INVESTIGATOR(S): Barbara J Bond

ORIGINATOR(S): Scott Thomas Allen

DATA SET CREDIT:

Data and financial support were provided by the HJ Andrews Experimental Forest research program, funded by the National Science Foundations Long-Term Ecological Research Program (DEB 08-23380)

METADATA CREATION DATE:

9 Jan 2013

MOST RECENT METADATA REVIEW DATE:

28 Jan 2014

KEYWORDS:

interception, throughfall, water balance, evaporation

PURPOSE:

Our goal was to develop a better understanding of the canopy processes that control the isotopic variations of throughfall. Additionally we were interested in patterns of throughfall isotopic composition and depth. Better understanding of throughfall patterns in heterogeneous terrain is important because since both rainfall and vegetation patterns are highly variable in complex terrain, and summer interception loss could be an important control over the spatial variability of the availability of moisture, coinciding with when vegetation is most water-limited.

METHODS:

Experimental Design - MV003:

Description: Two trees were selected for rainfall/throughfall analysis, one on the north slope and one on the south slope. A control was also constructed in a corresponding open area. During the first year of collection, the sampling was sporadic and samplers randomly placed. During the second year of collection, samplers were placed in coordinated locations under douglas fir trees of similar sizes and 18 of 36 collectors were randomly collected, and their water isotopic compositions analyzed.

Instrumentation: Picarro Water Isotope analyzer

Field Methods - MV003:

Description: Throughfall collectors during the fall used were commercially fabricated raingages, listed as EZ-read raingages, constructed by headwind consumer products, inc. These were a long tube with a 7390 sq. mm collection area. In the spring, Throughfall was collected using gages we constrcuted from standard polyethylene 2l and 4l jugs. A 4 liter jug had the bottom cut off, used as a funnel. This funnel connected to a 2l bottle used as a the colletion bottle. They were connected by two caps attached with eight 1/8" holes drilled through.

Citation: Allen, S. T., Brooks, J. R., Keim, R. F., Bond, B. J. and McDonnell, J. J., 2013. The role of pre-event canopy storage in throughfall and stemflow by using isotopic tracers. Ecohydrology. doi: 10.1002/eco.1408 Allen S. 2012. Trickle-down ecohydrology: complexity of rainfall interception and net precipitation under forest canopies. Thesis, Oregon State University.

SITE DESCRIPTION:

Two plots located on WS1 with indefinite boundaries. For the fall, collection of throughfall was on a haphazardly placed collectors along the WS1 trail, with collectors 8-13 being located south of the stream, along the first switchback ascending the north-aspect slope. Collectors 1-7 were located along the trail, on the section north of the stream, paralleling the stream. All collectors were under Douglas-fir trees. During the spring collection period, a different sampling regime was used. Plots were located on both the north and south aspect slopes (coordinates are listed in metadata). Within each of the plots there were 36 potential collection locations. Of these 36 locations, 18 were randomly selection and sampled for each collection period. Therefore, collector number refers to a collection location that is permanent, rather than a specific collector used.

TAXONOMIC SYSTEM:

Garrison et al., 1976

GEOGRAPHIC EXTENT:

WS01 at the HJ Andrews Experimental Forest

ELEVATION_MINIMUM (meters):

1027

ELEVATION_MAXIMUM (meters):

439

MEASUREMENT FREQUENCY:

irregularly, dependent on precipitation events

PROGRESS DESCRIPTION:

Complete

UPDATE FREQUENCY DESCRIPTION:

notPlanned

CURRENTNESS REFERENCE:

Ground condition