Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Scenario analyses

The objective of the research was to evaluate the combined ecological and economical implications of nature-based management systems in European beech forests, with respect to tree regeneration, coarse woody debris (CWD) biodiversity, nutrients, profitability, and other anticipated end-user questions. Two simulation models, i.e. Regenerator and FORSPACE, were used in a number of scenarios that simulate nature-based management of beeches.

Regenerator is a stand level regeneration model while FORSPACE predicts larger scale and long-term consequences of different alternatives of natural-based management of beeches. The Regenerator model was adjusted to include 13 silvicultural systems defined in cooperation with forest managers in Denmark, Germany, and Slovenia and tested in each of the three countries. In addition, a few selected silvicultural systems were replicated in Denmark and Germany with variations in the browsing level, resulting in a total of 51 scenarios. FORSPACE was set up to simulate developments of beech stands when management is aimed at converting even-aged forests to a more natural, irregular structure. It considers what strategies and regimes are appropriate to achieve this and what ecological and silvicultural outcomes will be. In FORSPACE, scenarios were developed for UK, The Netherlands, and Hungary.

From scenario analyses with Regenerator it can be concluded, that the uncertainty about the choice of a silvicultural model for nature-based management of beech in Europe remains. The scenarios did not clearly point at a specific strategy for conversion of even-aged to uneven-aged management of beech forests. But neither did they identify any limitations in those systems.

From the scenario analyses with FORSPACE, the results show that model can be used to realistically simulate the development of beech stands under a range of conditions and different silvicultural treatments and that it can be used to determine the outcome of different forest management regimes for European beech forests. For the UK and The Netherlands results show that various regimes can be used to convert even-aged beech stands. A successful approach could be to harvest some of the forest earlier and some later than normal (extending the rotation for the final crop trees), especially because this can maintain a reasonably high stocking and gradual harvest of trees over time. Furthermore, the scale of gap cutting used for conversion has a profound effect on the stand structure generated. Changes in the forest composition generated during the conversion will have knock on effects in terms of tree seed production and thus the potential for natural regeneration of different species.

A new and important aspect of the model is that it provides outputs that can be used to assess the consequences of a management regime on biodiversity, particularly the number of associated species of fungi, mosses and higher plants on coarse woody debris (dead logs). For example, it indicates that there is a tendency to find more associated species when beech is managed on an extended rotation (of up to 200 years) as this leads to a higher input of dead wood. However, it should be noted that this measure is scale dependent: the larger the forest considered the greater the number of species that are likely to exist. Although this is still valuable information, it makes it difficult to provide general guidelines for management regimes intended to promote biodiversity.

Finally, the model can also be used to demonstrate the potential trade-off between biodiversity gains and timber-quality where beech is managed on an extended rotation. In particular, the model can be used to assess the potential development of red heartwood formation in mature beech trees, which is an additional aspect to a reduced harvest where an extended rotation is used. The model indicates that where the rotation age is extended to 200 years, there is a strong increase in the probability of red heartwood formation. This can include up to 30 - 40% of the harvest, compared to only 1 - 5% when rotation ages of 120 - 150 years are used.

FORSPACE will be used in future studies on the impact of forest management on forest dynamics and biodiversity.

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Institutt for naturforvaltning
N-1432 Ås Norge
Norway
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