Skógræktarritið - 15.05.2001, Blaðsíða 209

educating and informing the tree
planters.
Effects on nature
Changes to soil and groundwater
chemistry can occur with any
change in vegetation. The ques-
tion then is whether or not these
effects are likely to be harmful in
some way. Some soil and ground-
water chemistry research has
been done in lcelandic forests in
recent years, with results not indi-
cating any obvious problems.
Considering the proposed scale of
afforestation, this is a non-issue.
Effects of afforestation on ero-
sional processes are generally
positive, since afforestation is
often used to help prevent ero-
sion or to revegetate eroded land.
Changes in biodiversity, espe-
cially changes to habitats where
rare species can be found, is
probably the environmental
aspect of afforestation that we
should be most concerned with.
Afforestation changes conditions
profoundly at the site level, in
some cases leading to nearly
complete replacement of the
biota on the site. This however
depends on what was on the site
before-hand and the tree species
planted. An eroded site planted
to larch will in time regain a sim-
ilar or higher level of species
richness and will certainly be
much more productive than
before, but it will loose almost
all of its original biota, the
exceptions being lichens that
don't care whether they grow on
rocks or on tree bark. Moorland
planted to birch will on the other
hand retain a large number of
species, even shade-intolerant
plants. Research is needed to
better characterise the biodiver-
sity changes that occur with dif-
ferent afforestation techniques
and species. However, one can-
not ignore the current state of
biodiversity in lceland. Iceland is
depauperate in terms of biodi-
versity because of its Quaternery
history and isolation and biologi-
cal production is at a minimum
because of unsustainable land-
use after human settlement. All
of the land that will be afforested
was wooded at the time of settle-
ment but is now more or less in a
state of environmental degrada-
tion. The most common cover
types, moorland, desertified land
and grassland, are also the most
common afforestation sites.
Rare species and rare habitat
types are, by definition, rare. It is
therefore ulikely that they will be
disturbed by afforestation. Never-
theless, care must be taken to
avoid disturbing such sites. As
with archaeological sites, this is
best done through the planning
process and through education.
Design guidelines can also do
much to reduce the impact of
afforestation on site biodiversity.
These include f.ex. planting mix-
tures of broad-leaved species and
conifers rather than pure stands of
evergreens, not draining wetlands
for afforestation and using native
species where appropriate.
At the landscape level, afforest-
ation leads to increased biodiver-
sity by creating new habitat types.
There are no forests in large parts
of lceland and woodland species
are uncommon. The new forests
will be occupied by a great many
species regardles of whether the
trees planted are native or exotic.
The same applies on the regional
level, although the small scale of
afforestation efforts in lceland
results in the regional effect being
negligible.
Time
Afforestation is not like building a
dam or a road where the change
happens quickly and is finished.
The forest does not exist just
because trees have been planted.
In Iceland, it takes 10-20 years
from the time trees are planted
until they start affecting their sur-
roundings. All afforestation does
is to set ecosystem succession in
motion or to change the direction
that succession will take. The
changes are gradual and continu-
ous. Succession will not be the
same at any two places even
though you plant the same trees.
You cannot state "this is what it
will be like when the forest has
arrived". Therefore, environmental
impact assessment of afforesta-
tion is bound to be inaccurate at
best and at worst pure fiction.
Besides, if history teaches us any-
thing, it is that forests are much
more easily destroyed than re-
grown. Thus, if the environmental
effects of afforestation turn out to
be unacceptible, all you need is a
chain saw to remedy the situation.
Conclusion
Most effects of afforestation are
either seen as positive or at least
not cause for concern. However,
three things stand out as poten-
tial reasons for concern: 1) From
the point of view of the general
public, afforestation leads to
landscape change, 2) regarding
biodiversity, possible effects on
rare species and rare habitat
types are more important that
effects on biodiversity in general
and 3) from a cultural perspec-
tive, important archaeological
sites must be protected. it is
unlikely that EIA of afforestation
will result in changes in
afforestation planning since the
above factors are already taken
into account. The existence of
bureaucratic devices such as an
afforestation plan, list of rare
habitats, map of archaeological
sites or an EIA report does not
guarantee that they will be fol-
lowed. When all is said and
done, it is the individual farmer
or tree planter who must bear
responsibility for their actions.
SKÓGRÆKTARRITIÐ 2001 l .tbl.
207