| dc.description.abstract | Stand structure, biomass production and dynamics of
white spruce (Picea glauca (Moench) Voss) were investigated
in four plantations, ages 4, 10, 18, and 28 years,
respectively, on similar lacustrine soils. Dry matter
partitioning of the white spruce component at the individual
tree and stand levels and under varying densities of
trembling aspen (Populus tremuloides Michx.) was analyzed.
A general pattern of stand development tied to: (1)
the timing and severity of site preparation preceding
plantation establishment; (2) the nature and distribution
of the post-cut vegetation; (3) soil and site conditions;
and (4) the successional processes in the tree strata, was
proposed which may also be applicable to plantations other
than those in the study.
Major differences in stand structure, biomass
partitioning and distribution, within the white spruce
populations of each plantation existed. This variation was
attributed to differences in micro-site condition and the
density of trembling aspen and other herbaceous vegetation
surrounding the planted white spruce. Severe scarification
using a modified V-plough prior to establishment of the two
youngest plantations resulted in highly variable early
height and diameter growth and survival of the planted white
spruce.
Both planted white spruce and second-growth aspen
produced maximum height growth and biomass on micro-sites
with deep surface horizons (Ah) where mixing of organic
matter with the surface mineral soil has occurred. The
presence of trembling aspen, graminoids, wild raspberry
(Rubus idaeus L.), prickly rose fRosa acicularis Lindl.),
and other woody tall shrubs during the stand initiation and
the stem exclusion stage were correlated with the decreased
height and diameter growth of the surviving planted white
spruce.
Total standing crop for all species and the white
spruce component of the plantations each increased with
plantation age; partitioning of biomass to stemwood and
foliage on individual spruce trees was significantly reduced
under high aspen densities and where the standing crop
biomass of graminoids, herbaceous plants and woody shrubs
was greatest.
Spruce foliage efficiencies for wood production
generally increased with stand age, decreasing aspen density
and increasing dominance (crown class). A clearly defined
and fully integrated biological model relating foliage
efficiency of the individual white spruce growing in
association with trembling aspen could not be developed.
However, white spruce foliage, stemwood and total tree dry
weights were explained in multiple regression models which
incorporated the biomass of competing species, soil/site
characteristics, and a measure of the percent cover of the
spruce seedling by competing vegetation. | |
