Plot Name: Reference Stand 20 (HJA)

Plot Size: 1.0 ha

Established: 1977

Remeasurements: 1983, 1988, 1993

Site Description

Latitude: 44.22

Longitude: 122.25

Elevation: 700 m

Aspect: SW

Slope: 75%

Landform: Smooth slope, upper 1/3 with rock outcrops

Soil Parent Material: Reddish tuffs and breccias

Soil: skeletal Frissell

Plant Association: Pseudotsuga menziesii/Holodiscus discolor

Age Class: second-growth

Soils:

The soil at one profile pit was described and sampled (see profile no. 297 in the HJA Soils Data Base). The soil profile is shallow and stony over a deep, very stony C horizon. The surface soil is about 10 inches thick and is made up of very gravelly, dark yellowish brown silt loam. The B horizon is about 12 inches thick and is comprised of very stony silt loam.

General Stand Description:

The stand is a second-growth stand about 110 years old and appears to have resulted from a fairly complete burn. The tree canopy is fairly dense and composed primarily of even- aged Pseudotsuga menziesii. All tree size-classes contain abundant Pseudotsuga, and smaller trees occur largely in patches under overstory openings. The composition of the tree layer hints at the xeric nature of the site with occasional Arbutus menziesii, Quercus garryana, and Pinus lambertiana scattered in the stand.

The tall shrub layer is highly variable with patchy distribution of the dominant Acer circinatum. Corylus cornuta and Holodiscus discolor each have moderate cover and are equally patchy in their distribution. The low shrub layer is dominated by Berberis nervosa. The shrub layers combined have a coverage of nearly 50%, but they appear to cover less due to patchy distribution with some areas having large openings and no shrub cover. Some of the dry site- indicator species in the shrub layer include Rhus diversiloba, Amelanchier alnifolia, Berberis aquifolium, and Symphoricarpos mollis, each with low coverage.

The herb layer is moderately well developed for this habitat type covering nearly one-third of the plot area. It is also patchy in distribution. Grass cover (6%) and Whipplea modesta (6.2%) are the dominant species. Syntheris reniformis and Polystichum munitum are the other two important species in this stand. An additional 20 herb species occur in lesser amounts. The moss layer is dominated by Polytrichum juniperium and Homalothecium negaptilum, two very good indicators of open exposed, dry sites within the H.J.Andrews.

Stand Structure and Composition

Live Tree Data at Last Measurement

Basal area: 59.5 m²/ha
PSME-57.5 m²/ha
Stem Numbers: 484/ha
PSME-424/ha
Diameter distribution:
median-25.7 cm
quadratic mean-39.5 cm
maximum-168.6 cm
Age: not available
Height (measurements within the last 20 years):
PSME ave.=27.4 m (n=62, quadratic mean diam.=61.6 cm), max.=48.3 m.
Volume: 801.9 m³/ha
PSME-786.9 m³/ha
Biomass: 460.2 Mg/ha
PSME-450.8 Mg/ha

Coarse Woody Debris (measured in 1995):

The total volume and mass of logs is 82 m³/ha and 25 Mg/ha, respectively. The volume and mass of standing dead trees (snags) is 54 m³/ha and 18 Mg/ha, respectively.

Ecosystem and Population Dynamics (measurements for most recent interval, 1988-1993)

Net Bole Production: 5.1 Mg/ha/yr

Annual Mortality: 2.5 Mg/ha/yr

Percent of Trees Dying: total-1.1%/yr (35.7% were uprooted)

PSME-1.1%/yr