Biomass and Diversity

From the Chronicle Herald

By CHRISTOPHER MAJKA
T
HERE is a growing con-
troversy in Nova Scotia
with respect to forest
biomass harvesting such
as that being conducted by
Northern Pulp Nova Scotia
Corporation in the Upper Mus-
qudoboit area.
Environmental groups such
as the Ecology Action Centre
have voiced concerns about the
impacts and sustainability of
whole tree harvesting. David
Wheeler, dean of Dalhousie
University's faculty of manage-
ment and leader of the prov-
ince's biomass consultation
team, has encouraged the Nova
Scotia government to consider
the option, if conducted to the
highest possible environmental
standards. Wheeler says bio-
mass could generate 15 per cent
of the province's renewable
energy. Unaddressed and unan-
swered in this debate is how
such forest harvesting practices
affect the biodiversity of forests.
Natural forests are highly
diverse environments that sup-
port an immense number of
plants and animals that interact
with one another. A biodiverse
I,)


forest shelters many species
and is a resilient ecosystem as a
result of this diversity. It func-
tions efficiently as a photosyn-
thetic engine that absorbs car-
bon dioxide, releases oxygen,
and recycles many essential
nutrients through the soil.
This fall, I completed a study
for the Nova Scotia Species at
Risk Conservation Fund in-
vestigating the saproxylic bee-
tles of Nova Scotia. "Saproxyl-
ic" refers to forest animals
responsible for the decomposi-
tion of wood. This research
revealed an astonishing diversi-
ty of such beetles - some 786
species, a third of all the beetles
found in the province. This does
not include foliage-feeding
species, ground beetles, or those
that feed on carrion.
Of the 786 species found, 269
(34 per cent) were placed in the
most vulnerable "may be at
risk" category. This ranking
reflected their limited distribu-
tion within the province, and
hence potential vulnerability to
disturbance. Furthermore,
studies offorest beetles, con-
ducted over the past decade by
myself and several colleagues,
have shown that 33 per cent of


saproxylic beetles are also ap-
parently very rare.
One reason for such apparent
scarcity may be the long history
offorest management practices
in the region. These have em-
phasized short-rotation, mono-
culture plantations, clearcut-
ting, the use of insecticides, and
the virtual elimination of old-
growth forests. Although 73 per
cent of Nova Scotia's land base
is forested,less than 0.6 per cent
of that is composed of old-
growth forests.
Saproxylic beetles live in and
depend on the full spectrum of
forest microhabitats. Some
inhabit rotten wood, old
stumps, fallen branches and
mossy logs. Others are found in
decaying boles of old trees, at
sap flows or in bark. Some are
cambium feeders, eating the
inner bark offallen logs,
branches or dying trees; others
feed on the wood itself.
Ambrosia beetles excavate
galleries under the bark which
they then inoculate with fungal
spores, feeding on the mildews
that subsequently grow. Bracket
fungi, which grow on decaying
wood, are the food source and
home to a large diversity of


beetles. These beetles are, in
turn, fed upon by many forest
denizens such as woodpeckers.
These diverse natural micro-
habitats supply the conditions
and environment that allow
such beetles to thrive. An area
completely denuded of dead
wood for biomass harvesting, or
where only wood chips or shav-
ings cover the soil, is very dif-
ferent. It is not suitable for the
vast majority of saproxylic
beetles to survive in. The re-
moval of all dead wood, logs,
stumps and branches dramat-
ically alters the habitat. Such
concerns apply to both clear-
cutting and biomass harvesting.
Recent research on the West
Coast has shown it can take 100
years for the woody debris in a
forest to stabilize after a clear-
cut, and that fungi, which many
saproxylic beetles depend on,
declines up to 97 per cent in
clearcut areas.
Other concerns aside, if we
wish to protect the biodiversity
offorests in Nova Scotia, and
ensure that they function as
vibrant ecological environ-
ments, we need to cultivate
forest management practices
that are much more selective in


their impact, and preserve fea-
tures of the natural environ-
ment. Old stands need to be
spared,large clearcuts should
be avoided, corridors or clumps
of trees should remain where
forest species can survive and
disperse from, and dead wood -
not chips or shavings - needs
to be left on the ground.
My research on the forest
beetles of Nova Scotia indicates
there are reasons to be appre-
hensive about the consequences
of clearcutting and biomass
harvesting, particularly since
many beetles in the province
appear to be clinging precari-
ously to their existence. A 2004
study issued by the World Wild-
life Fund, called Deadwood -
Living Forests, noted that
"standing dead or dying trees,
fallen logs, and branches form
one of the most important - yet
often unrecognized - habitats
for biodiversity." In Nova Sco-
tia, we need to heed this lesson,
and not only let the tree fall in
the forest, but let it stay.
Christopher Majka is a biologist who
conducts research on the ecology and
biodiversity of beetles in Atlantic
Canada.
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