STAND DESCRIPTION
- Plot Name: Reference Stand 12 (HJA)
- Plot Size: 0.25 ha
- Established: 1972
- Remeasurements: 1976, 1981, 1986, 1991, 1997
- Site Descripton
- Latitude: 44.23
- Longitude: 122.12
- Elevation: 1020 m
- Aspect: W
- Slope: 30%
- Landform: uneven pediment footslope
- Soil Parent Material: alluvium-colluvium and till(?) from
andesite
- Soil: Haplumbrepts, Carpenter Series
- Plant Association: Abies amabilis/Vaccinium alaskaense/Cornus
canadensis
- Age class: Old-growth
Soils:
The soil profile at one location was described and
sampled (see profile no. 90 in the HJA Soils Data Base). The
surface horizons were gravelly sandy loam, with the subsoil
being gravelly loam. In the surface gravel and cobbles made
up about 45-55%, and amounts increased in the subsoil to 60%.
Depth of the solum was about 90 cm. and the soil was well
drained. The bulk density was low, only reaching 0.8 g/cc in
the subsoil. Organic matter content was 5.7% in the surface
horizon (A1) and 4.9% in the B2.
General Stand Description:
RS 12 is near modal for the ABAM/VAAL/COCA habitat
type. A roadside location has led to some disturbance, but
most of the stand characteristics agree with those discussed
by Dyrness et al. (1974) for the ABAM/VAAL/COCA habitat type.
The tree layer of this dense stand is composed of
mature, old-growth Pseudotsuga and Tsuga heterophylla. The
understory trees are dominated Tsuga heterophylla. Abies
amabilis and Thuja plicata are also present in the
understory.
The tall shrubs are dominated by Acer circinatum,
medium shrubs by Vaccinium alaskaense, and low shrubs by
Berberis nervosa. Diversity is high with 18 shrub species,
but the cover of the layer is low for species other than
those mentioned.
The herb layer is dominated by Cornus canadensis and
Clintonia uniflora. Linnaea borealis, Chimaphila umbellata,
Smilacina stellata, Tiarella unifoliata, Viola sempervirens,
Achlys triphylla, and Xerophyllum tenax are also common.
Rhytidiopsis robusta is the dominant moss species with an
average cover of 12.7%.
- Stand Structure and Composition
- Live Tree Data at Last Measurement
- Basal area: 105.3 m2/ha
- PSME-63.2 m2/ha
- TSHE-41.0 m2/ha
- Stem numbers: 220/ha
- TSHE-120/ha
- PSME-48/ha
- ABAM-28/ha
- Diameter distribution:
- median-59.0 cm
- quadratic mean-78.1 cm
- maximum-182.1 cm
- Age: not available
- Height (measurements within the last 20 years): not
available
- Volume: 2026.9 m3/ha
- PSME-1193.3 m3/ha
- TSHE-823.3 m3/ha
- Biomass: 1075.8 Mg/ha
- PSME-688.4 Mg/ha
- TSHE-381.6 Mg/ha
- Coarse Woody Debris (measured in 1982):
The total volume and mass of logs is 312 m3/ha and 65
Mg/ha, respectively. The volume and mass of standing dead
trees (snags) is 381 m3/ha and 132 Mg/ha, respectively.
- Ecosystem and Population Dynamics (measurements for most recent
interval, 1991 to 1997)
- Net Bole Production: 11.1 Mg/ha/yr
- Annual Mortality: 22.2 Mg/ha/yr
- Percent of Trees Dying: Total-1.2%/yr (25% were uprooted)