STAND DESCRIPTION

Plot Name: Reference Stand 4 (HJA)
Plot Size: 0.25 ha
Established: 1972
Remeasurements: 1976, 1981, 1986, 1990, 1996
Site Description
Latitude: 44.27
Longitude: 122.14
Elevation: 1320 m
Aspect: W
Slope: 50%
Landform: smooth pediment backslope
Soil Parent Material: alluvium-colluvium and/or till
Soil: Haplumbrepts, Blue River Series
Plant Association: Abies amabilis/Tiarella unifoliata
Age Class: Old-growth

Soils:

The soil at one profile pit was described and sampled (see profile no. 80 in the HJA Soils Data Base). Surface horizons were silt loam in texture and subsurface horizons (B1 and B2) were silty clay loam. Gravel and cobble content varied from 25 to 45% by volume. The soil profile was well drained and had an average depth of 100 to 120 cm. Bulk density was very low--only 0.5 gm/cc in the surface and 0.8 gm/cc in the B2 horizon. Organic matter content was 9.1% in the A1 and 2.3% in the B2 horizon.

General Stand Description:

Reference Stand 4 is representative of the ABAM/TIUN habitat type described by Dyrness et al. (1974). The decreased cover by mature Abies procera and increased mature cover by Abies amabilis show the succession of tree species of high-elevation forests in the Andrews region and in most of the western Casade Mountains of Oregon and Washington. Although the shrub layer as a whole is poorly developed, Pachystima myrsinites is abundant. The herb layer shows the characteristic decrease in Rubus lasiococcus and Pteridium aquilinum and increase in Tiarella unifoliata in transition from the ABPR/CLUN to the ABAM/TIUN communities described by Dyrness et al. (1974).
This stand has a moderately dense overstory canopy of old-growth Pseudotsuga and Abies procera. Abies amabilis and Tsuga heterophylla are emergent. The stand also contains an occasional understory Tsuga mertensiana.
Immature trees are dominated by Abies amabilis and Tsuga heterophylla is secondary.
Most of the cover within the shrub layer is immature conifers. Tall shrubs are rare and unimportant. Vaccinium membranaceum, an abundant low shrub, dominates the shrub layer that exists.
The well-developed herb stratum is rich in species and cover. No single herb is dominant, but Achlys triphylla, Cornus canadensis, Xerophyllum tenax, Tiarella unifoliata, Clintonia uniflora, and Valeriana sitchensis make up most of the cover. The other 27 species in the layer are more scattered and less important. The moss layer is poorly developed.
Stand Structure and Composition
Live Tree Data at Last Measurement (1996)
Coarse Woody Debris (measured in 1982):
Ecosystem and Population Dynamics (measurements for most recent interval, 1990-1996)
Net Bole Production: 4.5 Mg/ha/yr
Annual Mortality: 5.5 Mg/ha/yr
Percent of Trees Dying: Total-1.7%/yr