Skógræktarritið - 15.05.2001, Side 82

grassy fields. If foresters learn to
the read the wind's signatures it
will give an enormous boost to
their skills in ecosystems man-
agement and plantation design.
Among the most obvious signa-
tures of surface wind patterns are
wind-shaped forests, the most
striking of which are the wave
forest and wave tuckamore phe-
nomena.
The relationship between wind
and soil type are inextricably
linked to forest longevity and sta-
bility. The report describes the
principal types of soils suitable
for plantation forestry and how
they affect root growth and ulti-
mately forest stability.
Persistent and often strong
wind, heavy loading by freezing
rain and desiccation resulting
from the blasting of foliage by
airborne ice-crystals, affects the
productivity of forests on the
Avalon Peninsula. Also, the
dynamics of very short-Iived
events, like a few hours of severe
freezing rain, gales, fire and even
a solitary bark beetle can be the
catalyst for major structural
changes across a forested land-
scape. Similarly, small changes
in planting practices, such as
improper storage and shipment
of seedlings, or a tree-planter
feeling poorly after a late night
out, can have major deleterious
long-term effects on the planta-
tion. Dynamically speaking, the
fundamental processes that trig-
ger's change and thus creates
new patterns and levels of biodi-
versity is called chaos or, in the
context of forestry, spatiotempo-
ral chaos. In the context of tree
planting, spatiotemporal chaos
comes onto play in the design of
plantations for harsh environ-
ments, where there is an inordi-
nate number of environmental
and human influences leading to
success or failure. In a nutshell,
the dynamical approach to plan-
tation forestry is to throw away
all the normal conventions of
regularity and design into planta-
tions the same roughness ele-
ments that natural forests have
developed as an adaptation to a
windy climate.
PART 3: TREES AS BIOLOGI-
CAL INDICATORS OF WIND
This section is intended to fine-
tune the forester's intuitive sens-
es that will enable them to better
'read' the dominant signatures of
the principal atmospheric and
soil influences on tree-growth.
Learning to read signatures of
complex physical phenomena in
the landscape pais dividends in
terms of improving forest pro-
ductivity and increasing the
longevity and stability of forests
and plantations.
Virtually every event in a forest
has a directional component. Of
all the directional influences on a
forest, wind perhaps is the most
obvious insofar as it shapes trees
and changes patterns of forests.
To some extent, wind is control-
lable. But in order to exert even a
modicum of control over the
wind, foresters must learn to
map its patterns, severity, and
direction. Related to wind expo-
sure is perhaps the more impor-
tant aspect of tree deformation
caused by freezing rain and wind-
borne ice crystals from the snow
pack. Knowing the severity of
freezing rain determines what
tree species should be planted.
Wind-borne ice crystals deform
saplings. Although trees will
eventually grow above the snow-
blasting layer, the long-term
effect is subdued growth.
Therefore, on windy sites, it is
important to factor snow-blast-
ing into design of a plantation.
There are many directional phe-
nomena that control forest
growth and patterns. Among the
obvious ones are wind throw,
and crown deformation by per-
sistent winds. However, response
of forests and plantations to
winds from different directions is
not always immediately clear. For
example, in some of the planta-
tions, westerly winds caused
crown deformation, whereas
strong northeasterly winds
caused endemic (sporadic) wind
throw of isolated trees, while
gale-force northerlys caused
wind throw of large patches.
Part 3 also introduces circular
statistics - another relatively new
paradigm - which enables
foresters to sort out direction of
atmospheric properties that
affect natural regeneration and
stand structure. This will enable
them to design more productive
and wind-firm plantations.
Circular statistics provide the
basic tools, by example, for
foresters who wish to quantify
directional phenomena such as
tree deformation, orientation of
wind throw, even the extent of
compression wood in boles and
correlated these with atmospher-
ic properties. These tools are
indispensable for plantation ori-
entation, exposure rating, seed
tree location, predicting spread
of natural regeneration and of
fire, blow-downs, etc.
PART 4: SEED COLLECTING
Native trees adapt to environ-
mental influences. The typical
practice of seed collection is to
choose the dominant and/or the
best formed trees. This works
well enough if the seeds are
raised to seedlings destined for
plantations in relatively benign
sites. But for the early stages in
reforesting denuded areas, it is
advisable to be more concerned
with hardiness, than height and
form.
A brief discussion on the mer-
its of collecting seed from a
broader range of phenotypes is
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SKÓGRÆKTARRITIÐ 2001 l.tbl.