Nicola Arndt und Matthias Pohl - Neobiota

and site conditions as well. In this paper we use the coincidence between potential natural vegetation
units and corresponding natural forest ecosystem types in order to map natural potentials of net
primary production and carbon storage.
Based on a comprehensive data material, models of net primary production and carbon storage in
different aboveground compartments were developed for the most widespread natural forest types. The
potentials of average net primary production and the carbon storage potentials in aboveground
biomass of different forest types were compared at the time when the average net primary production
attains a maximum. Organic carbon content of the corresponding forest soils comprise organic layers
and carbon content of mineral soils down to 80 cm. Underground organic carbon storage in roots was
estimated for the different forest types according to common assumptions.
Based on these models and the map of natural vegetation of Europe, the natural potentials of average
net primary production (ANPP) of aboveground phytomass were calculated and mapped for a northcentral
European region of about 19 million hectares. The spatial average of natural ANPP-potential of
this region is about 8.75 tons of dry matter per hectare and year. The variation of climatic and soil
conditions within the considered region leads to a span of about 6 tons of dry matter per hectare and
year between different locations.
A comparison of the natural ANPP potential and that one obtained with the current vegetation in the
woodlands of East German federal states (3 million hectares) reveals that forests with a natural tree
species composition would be able to produce about 0.6 tons of wood (dry matter) per hectare and
year more than current forests which are dominated by coniferous trees. The ratio of ANPP potentials
(wood biomass) of current and natural vegetation defines an ecological efficiency of wood production
which is about 86 % in the East German forests on average.
The calculation of carbon storage potential reveals large differences between forest ecosystem types.
Most important for carbon storage are the swamp and fen forests with storage capacities of about 600
tons per hectare. By contrast, only about 100 tons organic carbon per hectare are stored in natural
coniferous forests. The mapping of the natural potential of carbon storage for the north-central
European region considered above yields an average of 243 tons carbon per hectare (134 t C / ha in the
vegetation and 109 t C / ha as soil organic matter).
The actual carbon-storage potential on the surface area of the East German federal states
(10.7 millions hectare) has been diminished by one and a half billion tons carbon or 56 % compared to
the natural potential. This is mainly due to the medieval clearings as a result of which forests have
been reduced to 28 % of the surface area of the East German federal states. The natural potential of
organic carbon storage in the current woodlands is about 228 tons carbon per hectare. Current forests
which are dominated by coniferous trees have a storage potential of 91 % of the natural potential, i.e.
208 tons carbon per hectare.
The natural potential of organic carbon storage of the total land surface of the East German federal
states amounts to 50 annual rates of contemporary CO2 emission generated on this area by industry,
settlement, and traffic. The total carbon loss due to clearings and land use in the past amounts to
28 annual rates of present civilization output of CO2.
On the present woodland area, permanently a maximum of 10 % of the present CO2 emission rate of
East German federal states could be compensated by utilizing 80 % of the wood increment as timber
or as a substitute for fossil energy.
These estimations show the limited potential of atmospheric CO2 reduction by afforestation and timber
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