Environmental Engineering Reference
In-Depth Information
8
Ecosystem Services
of Biodiversity
T
HE BOREAL FOREST
,
GIVEN ITS CIRCUMPOLAR DISTRIBUTION
(
FIGURE
3.2),
is among the most expansive regions of the globe.As a consequence, it has
enormous economic value because it is an important source of timber and
pulpwood. Boreal ecosystems are therefore routinely subject to large-scale
forest harvesting, often in the form of clear-cut harvesting. A limiting fac-
tor in long-term sustainability of the forest industry is the boreal forest
ecosystem's capacity to regenerate following harvesting. In particular, bo-
real forest ecosystems contain mixtures of hardwood aspen (
Populus tremu-
loides
) that are sought by the pulp, paper, and plywood industries and
softwoods like white spruce (
Picea glauca
) that are sought largely by the lum-
ber industry. Historically, attempts to regenerate such mixed woods after
clear-cut harvesting have largely met with failure because in many instances
only aspen, a dominant competitor species, proliferates and suppresses re-
generation of spruce.This gives rise to vast aspen monocultures that risks
putting the softwood lumber industry out of business.
Regenerating the mixed wood forest is a desired goal of the forest in-
dustry. But current forest management practices can make regeneration an
expensive enterprise. It first involves intensive postharvesting site prepara-
tion with heavy machinery to create conditions that discourage rapid aspen
growth.This is followed by intensive replanting of spruce seedlings, plants
that are reared in tree nurseries. In some cases, the return on investment can
be marginal at best when these management costs are discounted for net
present value over the fifty to sixty year period required to regenerate the
forest. One solution to make forest management more cost-effective is to
dispense with the expensive site preparation and instead enlist biodiversity
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