Site description

This study was conducted at the Wind River Canopy Crane Research Facility (WRCCRF), located within the T.T. Munger Research Natural Area of the Gifford Pinchot National Forest, in southwestern Washington, USA (Figure 11.1). The site is located on a gently sloping alluvial fan in the Wind River Valley in the Cascade Mountains. Site characteristics are listed in Table 11.1. A Liebherr 550HC tower crane is located in the center of the 4 ha study area, and was used as a sensor platform for micrometeorological measurements (Figure 11.2). The crane is 85 m high, with a jib range of 87 m that inscribes a 2.3 ha circular area within the plot where hydrological measurements were made. The physical setting, ecological characteristics, and infrastructure of the WRCCRF are described in detail by Shaw et al. (2004).

Legend * Canopy Crane

Meteorological Stations: Continuous soil water content (2), soil temperature profile, snow depth, canopy temperature ■ >. TDR nods (0.4 m) a Segmented TDR nods (1.2 m) Piezometers Streamflow gauge Contour lines (m a.s.l)

Easting (m)

Figure 11.1 Location of the Wind River Basin and the WRCCRF in Washington State, USA

Legend * Canopy Crane

Meteorological Stations: Continuous soil water content (2), soil temperature profile, snow depth, canopy temperature ■ >. TDR nods (0.4 m) a Segmented TDR nods (1.2 m) Piezometers Streamflow gauge Contour lines (m a.s.l)

Easting (m)

Figure 11.1 Location of the Wind River Basin and the WRCCRF in Washington State, USA

Table 11.1 Basin characteristics

Name of basin Mountain range Elevation range of entire catchment (m) Elevation range of individual sites (m) Latitude and longitude Area (km2) Geology % glacierized

Vegetation type (dominant) % forested

Mean Q at catchment outlet (mm)

Wind River, Washington Cascades, USA 60-1600

368-381

Mainly basalt and alluvium

Douglas fir/western hemlock forest 97% 1850

Dominant vegetation species at the site are Douglas fir (Pseudotsuga menzesii), western hemlock (Tsuga heterophylla), and western red cedar (Thujaplicata), with many individual trees exceeding 500 years in age. The canopy height is approximately 60 m, with the tallest trees reaching 65 m (Ishii etal. 2000). The canopy exhibits many old-growth characteristics, including a high degree of spatial heterogeneity, a multilayered canopy, and a high degree of biodiversity in the plant community (Franklin and Spies 1991). Understory tree species include pacific yew (Taxus brevifolia), Pacific silver fir (Abies amabilis), and vine maple (Acer circinatum). Dominant species of the lowest layer include salal (Gaultheria shallon), Oregon grape (Berberis nervosa) and vanilla leaf (Achlys triphylla). The average leaf area

Figure 11.2 Wind River Canopy Crane Research Facility (WRCCRF). Photo by A1 Levno, USFS PNW/OSU Forest Science Data Bank

index (LAI) of the site was 8.6 ± 1.1, ranging from 9.3 ± 2.1 to 8.2 ± 1.8 measured by the vertical line intercept method over a three-year period (Thomas and Winner 2000).

A thick litter layer composed of coarse and fine woody detritus, needles, leaves, and mosses, ranges from roughly 0.02 to 0.10m depth across the site. Soils at the site originated as a deep volcanic ash deposit, and are described as shotty loamy sands and sandy loams. Soils are classified as frigid andisols, with low bulk densities (800-1100 kgm—3), and high porosities (0.5-0.75) (Dyrness 2003).

Climate at the site is characterized by cool, wet winters and warm, dry summers, with an average annual precipitation of 2470 mm, measured at the Wind River Ranger Station (WRRS) approximately 2.5 km south of the site. Less than 10% of the precipitation occurs between June and September (Shaw et al. 2004). Snowfall is most common from November to March and varies widely between years because the site is located near the lower limit of the transient snow zone. Mean annual air temperature is 8.7°C, with the mean monthly maximum of 17.3°C occurring in August and the mean monthly minimum of—0.1 °C occurring in January. Soil freezing occurs rarely at the site and is limited to the top several mm of soil.

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