MARINGEOLOGI & GLACIOLOGI
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Natural forest dynamics in Danish natural or semi natural woodlands
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Storms and a high ground water table are among the most important dynamical factors In Draved Forest. Storms create glades and openings in the canopy and initiate regeneration. The high water table has an important role for the tree species distribution in the wood, and in general makes the trees more sensitive to storm
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For further information on the project contact:
Email
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pfm@geus.dk
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In order to obtain a better basis for the interpretation of pollen analytical investigations (pollen diagrams), state geologist at DGU (Geological Survey of Denmark, now GEUS) Johannes Iversen, initiated a research program in Draved Skov (Forest) in SW Jutland in 1948.
Draved Forest is a woodland with remarkable undisturbed soils with thick layers of raw humus and in parts unusually long continuity in mixed deciduous stands of lime (Tilia cordata), alder (Alnus glutinosa), pedunculate oak (Quercus robur), birch (Betula pubescens), ash (Fraxinus excelsior), beech (Fagus sylvatica), crab apple (Malus sylvestris), hazel (Corylus avellana) and holly (Ilex aquifolius). Lime was one of the most important species in the Danish virgin forests in the Atlantic period.
The studies includes e.g. mapping of the canopy trees in the stands and periodically measurements and monitoring of tree increment, health and competitive status of each tree (diameter larger than 10 cm in 130 cm), regeneration, ground floor vegetation and soil acidity (pH). The annual pollen deposition is monitored by pollen traps.
In 1969 similar investigations was initiated in a mixed stand of beech (Fagus sylvatica) and sessile oak (Quercus petraea) in a small non intervention reserve at Løvenholm Estate, Djursland, East Jutland.
Combining recent pollen deposition data with data from the forests surveys formed the basis for establishing correction factors. The correction factors solved the problem related to the fact, that pollen production is different from tree species to tree species. With use of correction factors the pollen diagrams show the most plausible share of the vegetation (the canopy) of each tree species.
During the years, GEUS has made a number of forest historical and geological investigations in these and other forests in order to elucidate forest development and history during centuries and millenniums as the undisturbed soils with thick humus layers and deposits in wet hollows suitable for pollen analytical studies have provided unique opportunities to link past and present in the forests.
Besides elucidating natural forest dynamics, the long records provide essential information on environmental and climate changes over the past more than 60 years.
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Edited by:
Jacob Geltzer, GEUS -
jgel@geus.dk
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Udskriftsvenlig 
