The structure and composition of mixed-conifer forest (MCF) in central Oregon has been altered by fire exclusion and logging. The resulting increased density, spatial contagion, and loss of fire resistant trees decrease the resiliency of this ecosystem to fire, drought, and insects. The historical and current composition and structure of...
Pseudotsuga menziesii dominates the forests of the Pacific Northwest.
But though it is dominat, Tsuaa heteroohylla or Abies amabilis
is usually climax. Many researchers have studied Pseudotsuga on the
widespread mesic sites where it is seral, but few have examined the
relatively rare ecosystems in which Pseudotsuga or its associate...
Shallow, rapid soil mass movements are common events and primary sources
of sediment in steep terrain of the Pacific Northwest.
Poorly vegetated debris deposits and scars resulting from landslides
remove land from the productive timber base, and are subject to
continuing erosion. To examine the impact of these events on...
Knowledge of stand structure, stand dynamics, and production ecology of
species mixtures lags well behind that of single-species, even-aged stands. Two
mixed-species spacing trials in central Oregon allowed investigation of mixed-species
dynamics in a controlled experimental setting. The first site, Pringle Butte, is a
mixture of ponderosa pine (Pinus ponderosa...
This study evaluated the effect of soil compaction on the growth
of natural regeneration on volcanic ash-influenced soils in the
southern Washington Cascades. Growth of 9 to 18 year-old sapling-.
sized Ponderosa pine (Pinus ponderosa Laws.) was studied on sites
ranging from 915 to 1006 m elevation in an area...
In the Oregon Cascade Range, conifer encroachment has reduced the extent of mountain meadows by as much as 50% since the mid-1940s. Although encroachment results in a general decline of meadow species abundance and diversity, species differ in their sensitivities to encroachment: some show rapid declines whereas others persist in...
Forests in the Pacific Northwest receive very little nitrogen through
atmospheric deposition and thus studying the nitrogen cycle in this region can
provide insights into how the unpolluted nitrogen cycle functions. I examined the
fate of organic nitrogen versus inorganic nitrogen and the effect of tamlins on N
The purpose of this study was to assess how growth of young to mature Douglas-fir
(Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sar.)
in mixed stands was influenced by the presence of residual trees. Fourteen paired plots with
and without residual trees were examined in a retrospective...
This study was conducted to investigate why root disease centers east of the
Cascade crest tend to be larger in diameter and more abundant than their counterparts to
the west, within subalpine forest stands of central Oregon. The trend in a 290 km² study
area appeared opposite of what was...