Objectives and Definitions
Hubert Hasenauer
Institute of Forest Growth Research, University of Agricultural Sciences
Peter Jordan Str. 82, A-1190 Wien
e-mail: Hubert.Hasenauer@boku.ac.at
Tel: ++43-1-47654-4205
Fax: ++43-1-47654-4242
1. Introduction
This part will be extended to a general introduction including the
objectives of the different working groups as outlined below.
For centuries, European forests have been severely modified by humans. The result
is a change in tree species distribution, deterioration of forest soils and a reduction
in the area of forested land. Fast growing tree species such as Norway spruce and
Scots pine were promoted in large areas both within and beyond their natural range
in order to increase the growth of commercial timber. These secondary coniferous
stands turned out to be easily damaged by environmental stress factors such as air
pollution and climatic change. While the reduction of air pollution is mainly a political
issue, the question of conversion of secondary coniferous stands needs to also
consider economical and ecological risks and therefore is a major challenge for
forest ecosystem researchers.
Biodiversity: The variety, distribution, and abundance of different plants, animals,
microorganisms, the ecological functions and processes they perform, and the
genetic diversity they contain at local, regional or landscape levels of analysis
(Dunster and Dunster 1996). Biodiversity has five principal components: (1) genetic
diversity as genetic variation within and between populations of species, (2)
taxonomic diversity or the variety of organisms, (3) ecosystem diversity which
expresses the three-dimensional structures on the earth's surface, including the
organisms themselves, (4) functions or ecological services - what do organisms
within a given ecosystem do for each other, for their surrounding and how does this
change over time, and (5) the abiotic matrix within which the above mentioned living
components exist (soil, water, air, and organisms, with each being interdependent on
the continued existence of the other).
Clear-cut or clear felling: Felling of all trees within a fixed minimum area in size
(e.g. 0.5 ha or 2-3 heights of mature trees), resulting in a naturally regenerated or
planted even-aged forest stand. Hibbered (1991) extends this definition by
combining clear felling and replanting to ensure a successful restocking of the land.
Conversion (see transformation): The immediate change in species composition
and/or structure by forest management activities. For example planting a mixes
species forest on a formally stocked pure forest after clear-cut.
Continuous cover forestry: A forest management system without clear-cutting
including shelter wood cuttings, group and single tree selections, as well as target
diameter cuts. The oldest and most perfect examples is the "Plenterwald" or socalled plenter selection forest found in France, Switzerland, Slovenia and Germany
(Gadow et al. 2002). A slightly different definition is provided by (Mason et al. 1999):
continuous cover forestry is the use of a silvicultural system whereby the forest
canopy is maintained at one or more levels without clear felling.
Environmental impact: Addresses the potential reaction and/or change (positive
or negative) of an ecosystem due to any human or nonhuman activity over time. The
commonly used term "environmental impact assessment" may include social,
economic, cultural, biophysical, technological, and policy aspects. Environmental
impact assessment requires a definition of what is considered to be the
environmental system and what is the external disturbance or input supposed to
have an "impact". Impacts can be additive (the summary of individual impacts),
subtractive (the total impact is less than the sum of individual impacts due to
compensation effects), synergistic (the total impact is higher as the sum of individual
impacts).
Forest area: Defines a forest according to reproducible measures, as they are often
used in national forest laws, national forest inventories, etc. For example, the forest
area of some European countries are defined according to the FAO as follows:
Country
Minimum Width
Minimum Crown Cover
Minimum Production
Austria
10 m 30% 0.05 ha
Belgium
9 m /25 m - / 20%
0.01/0.05 ha
Czech Republic
20 m
0.01 ha
Denmark
20 m 30% 0.5 ha
France
15 m 10% 0.05 ha
Germany
10 m
0.1 ha
Ireland
40 m 20% 0.5 ha 4 m3/ha/a
The Netherlands
30 m 20% 0.5 ha
Poland
0.1 ha
Slovakia
0.1 ha
Sweden
0.25 ha
1 m3/ha/a
Switzerland 25 m - 50 m
20%
United Kingdom
20 m 20% 0.25 ha
Minimum
Area
Forest ecosystem: Includes the abiotic and biotic or living organisms of the forest.
It expands vertically upward into the atmospheric layer enveloping forest canopies
and downward to the lowest soil layers affected by roots and biotic processes. An
open system in the sense that it exchanges energy and materials with other systems,
including adjacent forests, aquatic ecosystems, and the atmosphere. Thus forest
ecosystems don't exist in
isolation, because mortality, regeneration and growth
including the interactions with the surrounding environment are essential for the
continued existence of the forest ecosystem.
Forest inventory: Periodic assessment of the forest including age class distribution,
density, damage, site quality etc. In combination with growth models (yield tables,
tree growth models, etc.), forest development and volume growth can be derived,
which is a prerequisite to develop sustainable forest management plans.
Forest in transition (see conversion): Indicates that forest management actively
changes the forest composition and structure due to a change in the management
objectives. For example moving from an even-aged to an uneven-aged forest and/or
changing the rotation period. Compared to conversion, it is not the immediate and
active change of species composition.
Mixed stand: A forest with more than one tree species. The criteria for
distinguishing a mixed stand vs. a pure stand may be different and commonly
depend on a predefined percentage of a specific stand variable: e.g. 10% of the
crown projection area (German National Forest Inventory), 10% of the total basal
area (Swiss Forest Inventory). There may be also other specific definitions according
to particular objectives.
Plantation: Forest stands established by planting or/and seeding in the process of
afforestation or reforestation. They consist either of introduced species (all planted
stands), or intensively managed stands of indigenous species. Usually, plantations
are even-aged and regular spaced with only a limited number of tree species but
conceptually this is not a strict requirement. An important difference may be whether
the plantation is established on formerly agricultural or forested land.
Potential natural vegetation (PNV): According to Tüxen (1956) the PNV is the
equilibrium species composition of an expected forest climax community at a
particular site considering current site conditions. This definition has been extended
by Kowarik (1997) to the idea of considering a particular state of the site. This
should address the fact that if a site has reached a certain level of degradation, the
PNV according to the definition by Tüxen will never be reached again. Another
definition suggests that the PNV is the community of plants that would grow at a
given site if no interference by human beings occur. (German Federal Nature
Conservation Agency 2000). A similar definition is given by IUFRO Terminology of
Forest Management (Nieuwenhuis 2000): PNV is the plant community established if
all successional sequences were completed without human interferences.
For our purpose we consider the PNV as the plant community that would develop at
a given site if no human interference were to occur.
Pure stand (see mixed species stand): A forest where more than 90% (e.g. by
basal area, crown projection area, etc.) consists of a single tree species.
Regeneration: Re-establishment of a forest stand by natural processes or planting
following a harvest of the previous stand or as a result of damage from natural
causes such as wildfire or storm.
Secondary forest (see also plantation): Stands that were established or
developed as a result of human action. Two types may be distinguished: (1)
secondary forests where human impact has affected the natural succession (e.g. pine
forest on a typical beech area as a result of litter raking and grazing), and (2)
plantations which replaced the (current) species composition following the potential
vegetation (e.g. planting spruce on naturally broad-leaved sites).
Transformation: (Überführung, see also Forest in Transition) The active
gradual change of the forest structure, species composition by forest management
activities (compare with conversion). For example moving from an even-aged to an
uneven-aged forest and/or a change in species composition. Compared to
conversion, it is not an immediate change of species composition.
Types of ownership: A classification of landowners according to predefined criteria
and/or legal issues such as private land or public land. It is often divided into three
groups: (1) Non industrial private land owners; (2) Industrial forest owners (Forest
companies); (3) Public, federal, state or other bodies such as communities
(townships).
FROM:
Norway Spruce Conversion: Options and
Consequences
European Forest Institute Research Report
Volume 18
Contents:
Foreword
Risto Paivinen
Introduction
H. Spiecker, J. Hansen, H. Hasenauer, E. Klimo, J.-P. Skovsgaard, H. Sterba and K.
von Teuffel
CHAPTER 1
Glossary of terms and definitions relevant for conversion
Hubert Hasenauer
CHAPTERs 2,3..8.