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Meyer P.,Nordwestdeutschen Forstlichen Versuchsanstalt | Lorenz K.,Naturwaldforschung der Nordwestdeutschen Forstlichen Versuchsanstalt | Engel F.,Nordwestdeutsche Forstliche Versuchsanstalt | Spellmann H.,Nordwestdeutsche Forstliche Versuchsanstalt | Boele-Keimer C.,Niedersachsisches Forstamt Saupark
Naturschutz und Landschaftsplanung

The state government of Lower Saxony aims at contributing to the German National Strategy on Biological Diversity by dedicating 10% of the state owned forests to natural development. The paper describes the first two steps of an approach to systematically refine the existing system of naturally developing forests: This is firstly the identification of hotspots and secondly the analysis of the representativeness of existing conservation areas. The first pool of hotspots has been defined as old-growth stands with typical biodiversity. The respective stands were identified by modelling their suitability as habitats for certain groups of indicator species. Forests on extreme sites are the second pool of hotspots. The respective stands were identified with the help of existing biotope maps. All potentially valuable stands were evaluated in the field by local foresters. If appropriate, additional stands were suggested. In July 2013, the existing forests with natural development in Lower Saxony amounted to 17.780 hectares or 1.5% of the whole and 4.4% of the public forests. The analysis of representativeness revealed deficits especially in respect of areas larger than 100 hectares and forests on soils with water surplus. Until September 2015 the process of refining the existing conservation system within the state forests shall be completed. © 2015, Verlag Eugen Ulmer. All rights reserved. Source

Overbeck M.,Nordwestdeutschen Forstlichen Versuchsanstalt | Schmidt M.,Nordwestdeutschen Forstlichen Versuchsanstalt | Nagel R.,Nordwestdeutschen Forstlichen Versuchsanstalt | Hansen J.,Nordwestdeutschen Forstlichen Versuchsanstalt
Allgemeine Forst- und Jagdzeitung

Natural adaptation processes in forest ecosystems cannot sufficiently offset the impact of projected climate change. Thus, active silvicuitural measures are imperative in order to maintain forest functions. Based on a 50-year simulation of silviculture policies as practised by the Lower Saxon State Forest, along with two contrasting scenarios, the consequences of diverse corrective measures on forest structure are projected and their ability to minimize risks are analyzed. Using the Harz Mountains in Lower Saxony as a model area, statistical models are applied to quanti1 potential risks at stand level such as water shortage, bark beetle infestation and windthrow. By estimating individual risk components, site-specific risk profiles are obtained. A method is introduced demonstrating how risk profiles can be transferred into concrete silvicultural adaptive measures. Compared to the current situation, all three simulation scenarios result in more stable silvicultural structures. Compared to the currently practised silvicultural regime the two alternative scenarios reduce the risks even further (Tab. 8) and yield a higher periodical total growth (Tab. 7). These idealized scenario simulation conditions encourage diversification in Norway spruce forests with low species diversity in the model area within 50 years (Fig. 3, 8) and lead, thus, to more stability. Measures designed to reduce risks, for example a reduction in girth limit, lead to very high planned cuts and considerable impacts on standing crop structure in the first 20 years of the simulation (Fig. 4, 5, 7). If no adaptation measures are taken, consequently the amount of risk-susceptible old Norway spruce stands will increase (Fig. 8, Thb. 8). The simulation scenario demonstrates that achieving extensive restructuring of Norway spruce stands within 50 years is possible only with great effort. In order to minimize risks resulting from climate change, adaptive measures should therefore concentrate on high-risk areas. The approach presented in this paper can be used as a conceptual framework to review current silvicultural practices as well as to complement future strategic silvicultural planning by quantitative risk components. Source

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