STAND DESCRIPTION
- Plot name: Reference Stand 3 (HJA)
- Plot Size: 1 ha
- Established: 1972 (expanded 1977)
- Remeasurements: 1976, 1977, 1981, 1986, 1992
- Site Description
- Latitude: 44.26
- Longitude: 122.16
- Elevation: 950 M
- Aspect: WNW
- Slope: 15-25%
- Landform: pediment footslope
- Soil Parent Material: alluvium-colluvium and/or glacial till
- Soil: Typic Dystrochrepts, Carpenter Series
- Plant Association(s): Tsuga heterophylla-Abies
amabilis/Linnaea borealis and Tsuga heterophylla-Abies
amabilis/Rhododendron macrophyllum/Linnaea borealis.
- Age Class: Old-growth
Soils:
The soil at one profile pit was described and sampled
(see profile no. 79 in the HJA Soils Data Base). Soil
textures throughout the profile were gravelly loams with
content of andesite gravel and cobbles ranging from 25-45%.
Solum is deep (about 1 m) and well drained. Bulk density was
estimated to be 0.6 g/cc in the surface and 0.8 g/cc in the B2
horizon. Organic matter content was 9% in the A horizon and
2.5% in the B2. Soil pH varied from 5.2 to 5.8.
General Stand Description:
Reference Stand 3 is representative of both the TSHE-
ABAM/LIBO and theTSHE-ABAM/RHMA/LIBO communities. The two
units typically occur in a mosaic of shrubby and nonshrubby
phases, with the principal shub species being Rhododendron
macrophyllum. The herb layer is less dense than that common
for the LIBO and RHMA/LIBO communities (Dyrness et al.
1974). However, most of the characteristic species of both
communities are abundant in this stand.
The overstory canopy of this stand is nearly closed and
is dominated by old-growth Pseudotsuga menziesii and emergent
Tsuga heterophylla and Thuja plicata. These overlie a layer
containing the smaller Abies amabilis. Reproductive trees
of all three emergent tree species are abundant, showing
that this community is transitional in the vegetation
gradient.
The shrub stratum is dominated by immature individuals of
Tsuga, Abies, and Thuja but includes large amounts of Taxus
brevifolia and Rhododendron macrophyllum in the tall shrub
layer. The low shrubs are dominated by Berberis nervosa.
The herb layer consists of patches dominated by Coptis
laciniata, Linnaea borealis, Chimphila umbellata, Cornus
canadensis, and Viola sempervirens. The moss layer is poorly
developed, as it is in most other high-elevation stands.
- Stand Structure and Composition.
- Live Tree Data at Last Measurement (1992)
- Basal Area: 90.9 m2/ha
- PSME-35.3 m2/ha, THPL-34.7 m2/ha
- TSHE-17.9 m2/ha
- Stem Numbers: 554/ha
- TSHE-327/ha
- THPL-91/ha
- TABR-63/ha
- ABAM-39/ha
- PSME-25/ha
- Diameter Distribution:
- median-13.3 cm
- quadratic mean-45.7 cm
- maximum-186.3 cm.
- Age: not available
- Height (at least 10 individuals measured within the
last 20 years):
- TSHE ave.=22.2 m (n=10, quadratic
mean diam.=44.8 cm), max.=50.0 m
- Volume: 1522.7 m3/ha
- PSME=668.6 m3/ha
- THPL=529.9 m3/ha
- TSHE=293.0 m3/ha
- Biomass: 715.9 Mg/ha
- PSME=385.7 Mg/ha
- THPL=175.8 Mg/ha
- TSHE=136.7 Mg/ha
- Coarse Woody Debris (measured in 1977):
The total volume and mass of logs on Reference Stand 3 is
603 m3/ha and 121 Mg/ha, respectively. The total volume and
mass of standing dead trees (snags) is 405 m3/ha and 91 Mg/ha,
respectively.
- Ecosystem and Population Dynamics (measurements for the most
recent interval, 1986-1992)
- Net Bole Production: -3.9 Mg/ha/yr
- Annual Mortality: 6.5 Mg/ha/yr
- Percent of Trees Dying: 1.1%/yr (48.6% were broken)