Assessment, Conservation and Sustainable Use of Forest Biodiversity

Assessment, Conservation and Sustainable Use of Forest Biodiversity
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SUSTAINABLE FOREST MANAGEMENT AUGMENTS DIVERSITY OF
VASCULAR PLANTS IN GERMAN FORESTS
G.von Oheimb*, H. Ellenberg**, J. Heuveldop***, W.U. Kriebitzsch**
*Institute for Ecology and Environmental Chemistry, University of Lueneburg, Germany;
** Institute for World Forestry, Federal Research Centre for Forestry and Forest Products, Hamburg, Germany;
*** Chair for World Forestry, University of Hamburg, Germany. –
E-mail: ellenberg@holz.uni-hamburg.de
Keywords: species diversity, vascular plants, forest management intensity, sustainable forest management Germany
Introduction
There exists a need in politics, administration, and in practice of forest management for knowledge and
decision support information on conservation and sustainable use of biological diversity in German forests.
Therefore the present study investigated the following hypotheses:
1) As a consequence of forest management, there exists a higher number of vascular plant species per unit
area in the herb layer of managed forests in relation to ecologically comparable non managed forests.
2) With growing management intensity, species composition in vascular plants shifts towards higher
fractions of indicator species for disturbance.
Methods
Vegetation analysis was conducted in 1997 and 1998 in broadleaved lowland forests of Northern Germany on
rich soils (county of Herzogtum Lauenburg, east of Hamburg: “SH”) as well as on moderately rich soils
(beech, Fagus silvatica, forests of the Mueritz National Park “MV”). Virgin forests do not exist in Germany. So,
non-managed (at least for 30 years, up to more than 150 years) forests were contrasted against managed forests
of different management intensity. The latter was measured among others as cubic metres of timber taken per
hectare and per year. Soil quality and water supply as well as tree species composition and stand age were as
comparable as possible. Contrary to no longer managed forests, thinning and final timber harvest were
conducted in managed forests.
Results
In almost every comparison, higher mean species numbers per unit area were found in managed forests as
opposed to no longer managed forests (Fig. 1 and 2).
In every investigated forest stand, managed or not, the widespread and frequent indicator species for the forest
types of Querco-Fagetea and Fagetalia (“typical” forest species in a narrow sense)existed in similar densities. On
the other hand, a significantly higher distribution and density was observed in managed forests for nitrophytes
and for indicator species for light (open canopy) and for soil compaction (Tab. 1 and 2). The steadyness values
of these latter species grows further with raising intensity of forest management (Tab. 1, Fig. 1).
Conclusions
Higher numbers of vascular plant species per unit area are possible in managed forests due to a better light
climate in the herb layer as a consequence of forest operations for timber harvest that open up the canopy.
Additionally, heterogeneous soil conditions (bare, accumulated, compacted, etc.) are caused by timber moving
operations and a higher forest road density, both leading to better conditions for establishment and growth of
vascular plants at least temporarily.
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