STAND DESCRIPTION
- Plot Name: Reference Stand 27 (HJA)
- Plot Size: 0.96 ha
- Established: 1978
- Remeasurements: 1983, 1988, 1994
- Site Description
- Latitude: 44.25
- Longitude: 122.18
- Elevation: 790 m
- Aspect: SSW
- Slope: 10%
- Landform: hummocky bench
- Soil Parent Material: colluvium of reddish tuff and breccia
- Soil: McKenzie River Series
- Plant Association: Tsuga heterophylla-Abies amabilis/
Rhododendron macrophyllum/Berberis nervosa
- Age Class: Old-growth
Soils:
Soils at two profile pits were described and sampled
(see profile nos. 313 and 314 in the HJA Soils Data Base).
The surface (A1) horizon was about 10 in. thick and consisted
of dark reddish brown shotty loam, with shot content
appoximately 15%. The subsoils are very deep and virtually
stone-free. The B2 horizon, extending to almost 3 ft. in
depth, is brown to reddish brown heavy silty clay loam with
coarse subangular blocky structure. This layer is underlain
by a B3 horizon of strong brown color and having fine, sitly
clay texture. Despite high amounts of clay, these soils are
well drained.
General Stand Description:
RS 27 is an example of a stand in the zone of
transition between western hemlock and Pacific silver fir
climaxes. In this stand, silver fir occurs, but only in
small amounts. It is classed as an old-growth stand with
tree ages greater than 450 years.
The overstory tree layer of the stand is composed of
dominant Pseudotsuge menziesii forming a dense canopy (65-75%
cover) along with emergent Tsuga heterophylla. Understory
tree cover is made up primarily of Tsuga heterophylla in all
size-classes and scattered reproduction of both Abies
amabilis and Thuja plicata.
The shrub layer is fairly well developed. Tall shrubs
are dominated by scattered Rhododendron macropyllum, patchy
Acer circinatum, and abundant Taxus brevifolia, each with
greater than 10% cover. There are only traces of other
shrubs within the reference stand.
The herb layer is sparse, having less than 20% total
cover. Linnaea borealis is the most abundant herb species,
but has a patchy distribution.
- Stand Structure and Composition
- Live Tree Data at Last Measurement
- Basal Area: 120.2 m2/ha
- PSME-78.6 m2/ha
- TSHE-24.8 m2/ha
- THPL-15.3 m2/ha
- Stem Numbers: 391/ha
- TSHE-188/ha
- PSME-66/ha
- TABR-82/ha
- THPL-46/ha
- Diameter Distribution:
- median-20.2 cm
- quadratic mean-62.6 cm
- maximum- 169.3 cm.
- Age: not available
- Height (measurements within the last 20 years):
- PSME ave.=63.8 m (n=12, quadratic mean diam.=114.8 cm)
- PSME max.=75.1 m.
- TSHE ave.=32.3 m (n= 21, quadratic mean diam.=56.5 cm)
- TSHE max.=70.2 m
- Volume: 2118.1 m3/ha
- PSME-1438.2 m3/ha
- TSHE-444.9 m3/ha
- THPL-221.9 m3/ha
- Biomass: 1118.3 Mg/ha
- PSME-829.1 Mg/ha
- TSHE-207.0 Mg/ha
- THPL-73.8 Mg/ha
- Coarse Woody Debris (measured in 1978):
The total volume mass of logs is 553 m3/ha and 108 Mg/ha,
respectively. The volume and mass of standing dead trees
(snags) is 46 m3/ha and 10 Mg/ha, respectively.
- Ecosystem and Population Dynamics (measurements for most recent
interval, 1988-1994)
- Net Bole Production: 4.6 Mg/ha/yr
- Annual Mortality: 18.0 Mg/ha/yr
- Percent of Trees Dying: total-1.2%/yr