STAND DESCRIPTION

Plot Name: Reference Stand 10 (HJA)
Plot Size: 0.25 ha
Established: 1972
Remeasurements: 1976, 1981, 1986, 1991, 1997
Site Description
Latitude: 44.23
Longitude: 122.22
Elevation: 610 m
Aspect: SE
Slope: 10 to 25%
Landform: pediment surface on ridge spur
Soil Parent Material: alluvium-colluvium from red breccia
Soil: Glossoboralfs, McKenzie River Series
Plant Association: Tsuga heterophylla/Rhododendron macrophyllum-Gaultheria shallon
Age class: Old-growth

Soils:

The soil profile at one pit was described and sampled (see profile no. 88 in the HJA Soils Data Base). The surface 30 cm of soil is silt loam in texture, with 10-20% gravel and shot content. The B2 horizons from 30 to 150 cm are made up of silty clay loam soil with only trace amounts of stones. Depth to saprolite is generally over 1.5 m. Bulk density of the surface soil was estimated to be 0.9 g/cc and the subsoil was 1.1 g/cc. Organic matter content was 3.3% in the surface horizon and only 0.3% in the subsoil.

General Stand Description:

This reference stand is an example of the TSHE/RHMA- GASH habitat type described by Dyrness et al. (1974), but it differs slightly in having unusually high tree cover by immature Pseudotsuga menziesii. RS 10 is best interpreted as representative of TSHE/RHMA-GASH, but tending toward the TSHE/CACH habitat type described by Dyrness et al. (1974).
The canopy of RS 10 is dominated by old-growth Pseudotsuga menziesii. Emergent Pseudotsuga, Tsuga heterophylla, and Thuja plicata are secondary. The most abundant conifer species in the understory, however, is Tsuga heterophylla.
The shrub stratum is exceptionally well developed. The tall shrub layer is dominated by Rhododendron macrophyllum and Acer circinatum. There is also a large contribution to the tall shrub layer by Tsuga heterophylla, Taxus brevifolia, and Castinopsis chrysophylla. The low shrub layer is also well developed and is dominated by Gaultheria shallon, with smaller amounts of Berberis nervosa.
The number of species and cover of the herb layer is greatly reduced as a result of the dense shrub cover. Xerophyllum tenax, Chimaphila umbellata, Linnaea borealis, and Polystichum munitum are the most common herb species. The moss layer, moderately well developed but patchy in distribution, is dominate by Eurhynchium oreganum.
Stand Structure and Composition
Live Tree Data at Last Measurement (1997)
Coarse Woody Debris (measured in 1982):
Ecosystem and Population Dynamics (measurements for the most recent interval, 1991-1997)
Net Bole Production: 7.4 Mg/ha/yr
Annual Mortality: 0.9 Mg/ha/yr
Percent of Trees Dying: Total-1.8%/yr (11.1% broken, 5.6% uprooted)