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Site Location and Description
The Date Creek silvicultural systems study is located
in the transitional coast-interior forests (Interior Cedar-Hemlock zone)
of northwestern British Columbia, approximately 20 km north of Hazelton
(55o 22’ N, 127o 50’ W). In this mountainous region
of B.C., climatic conditions can vary over relatively short distances.
The moderate to steep lower slopes of the Kispiox Range make up one half
of the study area. The rest of the area is a rolling morainal landscape,
dissected by many glacial meltwater channels. Morainal parent materials
dominate the area, ranging in texture from loamy sand to clay loam. Eluviated
Dystric Brunisols, Orthic Dystric Brunisols, and Orthic Humo-Ferric Podzols
are the most common soils; Hemimors and Mormoders are typical humus forms.
Forests in the research area are dominated by a mixture of conifer and
deciduous tree species. Mature forests (130-140 years since fire) are dominated
by western hemlock (Tsuga heterophylla), but are intimately mixed
with western redcedar (Thuja plicata), subalpine fir (Abies lasiocarpa),
lodgepole pine (Pinus contorta var.
latifolia), hybrid spruce
[the complex of white spruce (Picea glauca), Sitka spruce (P.
sitchensis) and occasionally Engelmann spruce (P. engelmannii)],
paper birch (Betula papyrifera), trembling aspen (Populus tremuloides)
and black cottonwood (Populus balsamifera ssp. trichocarpa).
Subalpine fir is commonly replaced by amabilis fir (Abies amabilis)
at higher elevations. In the old-growth stands (300 yrs+ since fire), western
hemlock dominates with minor components of western redcedar, subalpine
fir and amabilis fir.
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Background
The silvicultural systems experiment was established in
1992. The treatments represent differing amounts and patterns of tree removal.
Two levels of partial cutting were used and compared with both undisturbed
forests and clearcuts. In the light partial cutting treatment, approximately
30% of the stand volume was removed by cutting either single stems or small
gaps (3 - 10 trees). In the heavy partial cutting treatment, approximately
60% of stand volume was removed. The cutting pattern utilized both large
gaps (0.1–0.5 ha in size), evenly distributed across the treatment units
and either single tree or small gaps in the forest matrix between the large
openings. With the exception of scattered residual deciduous trees (mostly
trembling aspen and paper birch), all stems were removed in the clearcut
treatment
units. There were four replicates of each of the four treatments, organized
in a randomized block design; treatment units were approximately 20 hectares
in size. The intent was to create four differently structured stands that
would provide a wide variety of environmental conditions both between and
within treatments. In addition to creating four distinct levels of tree
removal (at the treatment unit scale), we wanted to establish a range of
canopy opening sizes. These ranged from the removal of single trees to
approximately 0.5 ha openings in the partially-cut treatment units, to
single large openings in the clearcut treatment units.
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Click Here for a list of the Date Creek Studies