STAND DESCRIPTION

Plot Name: Reference Stand 15 (HJA, Watershed 2)
Plot Size: 0.25 ha
Established: 1973
Remeasurements: 1976, 1981, 1986, 1992, 1998
Site Description
Latitude: 44.21
Longitude: 122.26
Elevation: 720 m
Aspect: NW
Slope: 60 to 80%
Landform: slightly concave pediment backslope
Soil Parent Material: alluvium-colluvium from andesite
Soil: Skeletal Haplumbrepts, Tidbits Series
Plant Association: Tsuga heterophylla/Polystichum munitum
Age Class: Old-growth

Soils:

The soil profile at one pit was described and sampled (see profile no. 91 in the HJA Soils Data Base). The surface soil was very dark brown gravelly loam and the subsoil was made up of dark brown gravelly silty clay loam. The content of gravel and cobbles was 40% in the surface and 45% in the B2 horizon. Depth to a very stony silt loam C horizon was 70 to 80 cm. Soil bulk density ranged from 0.7 g/cc in the surface to 0.8 g/cc in the B horizon. Organic matter content was 9.9% in the A horizon and 3.4% in the B2.

General Stand Description:

RS 15 is an old-growth community which is representative of the TSHE/POMU habitat type described by Dyrness et al. (1974). It is different from the TSHE/ACCI/POMU habitat type by having a less prominent shrub layer and larger amounts of Polystichum munitum. The tree canopy also contains considerable cover of Thuja plicata, which is characteristic of moist stands at low to middle elevations in the Cascade Mountains.
The tree layer is dominated by Pseudotsuga menziesii, with Tsuga heterophylla and Thuja plicata emergent or codominant in the canopy. Tsuga heterophylla and Thuja plicata, abundant in immature size classes, indicate that the habitat type is mesic.
The shrub layer is dominated by immature trees. Moderate amounts of Taxus brevifolia, Acer circinatum, and Cornus nuttallii are also in the tall shrub layer. The low sbrub layer is not well developed and is dominated by Gaultheria shallon and Berberis nervosa.
The herbaceous stratum is dominated by 16.5% cover of Polystichum munitum. Other species have low frequency. Eurhynchium oreganum is dominant among the relatively common mosses.
Stand Structure and Composition
Live Tree Data at Last Measurement
Coarse Woody Debris (measured in 1982):
Ecosystem and Population Dynamics (measurements for most recent interval, 1992-1998)
Net Bole Production: 4.6 Mg/ha/yr
Annual Mortality: 1.3 Mg/ha/yr
Percent of Trees Dying: Total-2.3%/yr (78.6% were uprooted)