More than 200 sites between 500 and 2000 meters elevation
were examined utilizing a reconnaissance sampling technique for a
portion of the eastern slopes of the northern Oregon Cascade Mountains.
Twelve different forested plant communities were described
with data on vegetation, soils and topography. A map of their distribution
and a key for their identification were presented.
The communities were grouped into four different series based
on climax tree species. The Pinus ponderosa-Quercus garryana
series dominated elevations between 600 and 850 meters and included
four community types. The Quercus garryana/Purshia tridentata/
Agropyron spicatum type was an open Quercus garryana woodland
found on upper southerly slopes with relatively shallow soils. The
Pinus ponderosa-Quercus garryana/Purshia tridentata/Festuca
idahoensis type was the most widespread member of the series and
was found on gentle slopes with east to south aspects. The Pinus/
ponderosa/Purshia tridentata/Lupinus leucophyllus type was found
on gentle east to south facing slopes on flat or convex microrelief.
The Pinus ponderosa/Purshia tridentata Lupinus caudata type was on
gentle east to south facing slopes having concave microrelief.
The Abies grandis series dominated elevations between 850 and
1500 meters and included four community types. The Abies grandis/
Carex geyeri type occupied the lowest elevations within the series and
was found on all aspects and slope positions. The Abies grandis/
Pyrola secunda type was found at the upper elevations on midslopes
with northerly aspects between 1360 and 1415 meters.
The Thuja plicata series was found in stream bottoms and
valleys between 1100 and 1325 meters elevation and included two
community types. The Tsuga plicata/Linnaea borealis var. longiflora
type was found on flat to concave microrelief with soils that had a high
ground water table. The Tsuga heterophylla/Linnaea borealis var.
longiflora type was found on lower sheltered valleys and side slopes.
The Abies amabilis series dominated the upper elevations of
the study area between 1500 and 1960 meters and included two community
types. Tsuga mertensiana was a conspicuous associate with
Abies amabilis. The understory vegetation was often depauperate
and poorly developed. Low shrubs were usually the most dominant
understory species. The Abies amabilis /Rubus lasiococcus type was
found at the lower elevations within the series on a variety of slopes,
aspects and topography. The Abies amabilis/Vaccinium scoparium
type occupied the highest elevations within the study area and subalpine
meadows and openings were commonly interspersed with it.
It occurred on north to east aspects on a variety of slopes and
Non-forested areas within the study area were not classified but
were briefly described. Some implications for management by community
were also given.
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