Skógræktarritið - 15.05.2001, Page 147

ARILD O. GAUTESTAD AND FRANS E. WIELGOLASKI
Dynamic modeling of the
mountain birch forest ecosystem:
challenges related to space,
time and scale
SAMANTEKT
Evrópuverkefnið „Samspil manna og birkiskógavistkerfis" (HIBECO)
beinist að samspili manna og umhverfis á svæðum þar sem birki
(Betula pubescens ssp. czerepanovii) myndar skógarvistkerfi. Tölvulíkan
verður notað til að fá heildstæða mynd af möguleikum til landnýtingar
og til að gera áætlanir um sjálfbæra nýtingu þessa vistkerfis. Þessu
hagnýta líkani er ætlað að tengja rannsóknir á mismunandi sviðum
plöntulífeðlisfræði, beitarvistfræði og félagshagfræði. Það er nokkuð
erfitt að hanna flókið líkan af víxlverkun ólíkra þátta, t.d. vaxtar skógar-
ins, beitar á trjánum og nýtingar manna á vistkerfinu. Til að raunhæft
hagnýtt líkan fáist verður að taka tillit til flókins samspils þátta á
ólíkum stærðarkvarða og í mismunandi loftslagi. í þessari grein er
tekist á við vandamál í hönnun líkansins.
The EU-funded project "Human
Interactions with the Mountain
Birch Forest Ecosystem" (HIBECO)
is focusing on the human dimen-
sions and natural conditions of
the Nordic mountain birch Betula
pubescens ssp. czerepanovii forest
ecosystems. Twenty scientists
from Finland, Sweden, Norway,
lceland, Greenland, UK, Germany
and Canada participate in the pro-
ject. The biology of these ecosys-
tems has been studied in less
detail over the last twenty years
through the Nordic Subalpine-
Subarctic Ecology group (NSSE).
Results from these studies are
presented in a UNESCO Man and
the Biosphere series volume
(Wielgolaski 2000). Based on
these results and results from the
HIBECO project, as well as results
from other sources, a computer-
based model is to be developed
as part of an integrative work con-
nected to formulation of manage-
ment scenarios and development
plans that will ensure future sus-
tainability of this ecosystem.
These aims are to be achieved in
an interdisciplinary manner, com-
bining birch productivity, her-
bivory and socio-economics.
From a modeling perspective
the cross-disciplinary integration
of interactions between birch for-
est growth, herbivory and anthro-
pogenic exploitation and other
interactions represents a great
scientific challenge. For example,
scaling complexities over space
as well as time under different
climatic scenarios will be consid-
ered in order to produce a model
that can contribute to the devel-
opment of guidelines for future
sustainable management. In this
paper some of these challenges
related to fine- and coarse scale
interactions in space and time
are illustrated by examples from
birch-insect interactions as a
part of the preparative phase of
the model development.
Various subspecies and vari-
eties of mountain birch form
vast, continuous forests in sub-
arctic and subalpine parts of
Fennoscandia, lceland, Green-
land, Scotland and in northwest-
ern Russia, particularly on the
Kola Peninsula (Vare 2000).
These forests are in some regions
mostly unmanaged by man,
while the trees in other parts
have been strongly influenced by
human activities. Mountain birch
is utilized for firewood and some-
times building materials like
wallboards, and especially young
birch shoots are important as
forage for domestic ungulates
like reindeer and sheep (e.g.,
Helle 2000, Aradottir and Arnalds
2000). Over the last centuries
patches and larger areas of birch
forests within some regions have
been transformed into summer
farming areas. Even if some of
these areas have been aban-
doned as farming and mowing
areas again (Bryn and Daugstad
2000) and have gradually been
reclaimed by birch (or reforested
with sprucel), the mountain birch
forests are still strongly influ-
enced by traditional forms of uti-
lization in parts of their distribu-
SKÓGRÆKTARRITIÐ 2001 l.tbl.
145