Plot Name: Reference Stand 1 (HJA, Watershed 9)

Plot Size: 1 ha

Established: 1971 (expanded 1978)

Remeasurements: 1976, 1978, 1983, 1988, 1992, 1998

Site Description

Latitude: 44.20

Longitude: 122.26

Elevation: 510 m

Aspect: SW

Slope: 30 to >65%

Landform: Interfluve with a portion of pediment backslope.

Soil Parent Material: red tuffs and breccias

Soil(s): Interfluve- Xerochrepts, Flunky (Zango) Series Pediment- Dystrochrepts, Frissell Series

Plant Association: Pseudotsuga menziesii/Holodiscus discolor

Age class: Old-growth

Soils:

Soils at two profile pits were described and sampled (see profile nos. 76 and 77 in the HJA Soils Data Base). Soil textures were uniformly loams with red breccia gravel content ranging from 50% in the Frissell to 65% in the Flunky. Soil depth was about 50 cm for the Flunky soil and 1.5 to 2.5 m for the Frissell. Bulk density of the soils was estimated at 0.9 g/cc and organic matter content of the surface horizons was about 7 and 10% for the Frissell and Flunky, respectively.

General Stand Description:

This old-growth stand is typical of the PSME/HODI habitat type and tree size class distribution indicates that this is a Douglas-fir climax habitat type, which is the driest type on the H.J.Andrews. The adjacent forest is mostly ecotonal to the Pseudotsuga menziesii-Tsuga heterophylla/Corylus cornuta and/or Tsuga heterophylla/Rhododendron macrophyllum-Gaultheria shallon habitat types.

This reference stand has an open tree canopy. The stand is dominated by Pseudotsuga menziesii in both mature and immature size classes. Data taken in 1972 show Tsuga heterophylla saplings, but all had died by 1976. Taxus brevifolia is an abundant understory tree species which maintains a shrub-like growth habit.

The shrub layer is dominated by Acer circinatum and Pseudotsuga menziesii. Corylus cornuta is secondary in the tall shub layer. Symphoricarpos mollis and Berberis nervosa are the most abundant low shrubs. The diagnostic Holodiscus discolor occurs with >2% cover.

The herb layer, with high species diversity, is dominated by Whipplea modesta and Polystichum munitum. Synthyris reniformis and Linnaea borealis are common to abundant in patches.

Stand Structure and Composition

Live Tree Data at Last Measurement

Basal area: 63.6 m²/ha
PSME-61.5 m²/ha
Stem numbers: 516/ha
PSME-427/ha
Diameter distribution:
median-30.5 cm
quadratic mean-48.1 cm
maximum-162.6 cm.
Age: not available
Height (measurements within the last 20 years):
PSME Ave.=35.4 m (n=14 quadratic mean diam.=82.5 cm)
Max.=45.7 m.
Volume: 916.9 m³/ha
PSME-899.0 m³/ha
Biomass: 526.4 Mg/ha
PSME-515.9 Mg/ha

Coarse Woody Debris (measured in 1995):

The total volume and mass of logs on Reference 1 is 172 m³/ha and 41 Mg/ha, respectively. The total volume and mass of standing dead trees (snags) is 116 m³/ha and 48 Mg/ha, respectively.

Ecosystem and Population Dynamics (measurements for most recent interval, 1988-1992)

Net Bole Production: 3.6 Mg/ha/yr

Annual Mortality: 11.9 Mg/ha/yr

Percent of Trees Dying: Total-1.0%/yr (47.6% were uprooted)

PSME-0.8%/yr.