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Ongoing climate change affects growth and increases biotic and abiotic threats to Germany's forests. We analysed how these risks develop through the mid-century under a variety of climate change scenarios using the process-based forest model 4C. This model allows the calculation of indicators for fire danger, late frost risk for beech and oak, drought stress and nun moth risk. 4C was driven by a set of 4 simulations of future climate generated with the statistical model STARS and with 10 simulations of future climate based on EURO-CORDEX model simulations for the RCP2.6, RCP4.5 and RCP8.5 pathways. A set of about 70000 forest stands (Norway spruce, Scots pine, beech, oak, birch), based on the national forest inventory describing 98.4 % of the forest in Germany, was used together with data from a digital soil map. The changes and the range of changes were analysed by comparing results of a recent time period (1971–2005) and a scenario time period (2011–2045). All indicators showed higher risks for the scenario time period compared to the recent time period, except the late frost risk indicators, if averaged over all climate scenarios. The late frost risk for beech and oaks decreased for the main forest sites. Under recent climate conditions, the highest risk with regard to all five indicators was found to be in the Southwest Uplands and the northern part of Germany. The highest climate-induced uncertainty regarding the indicators for 2011–2045 is projected for the East Central Uplands and Northeast German Plain.

Germany’s forests provide a variety of ecosystem services. Sustainable forest management aims to optimize the provision of these services at regional level. However, climate change will impact forest ecosystems and subsequently ecosystem services. The objective of this study is to quantify the effects of two alternative management scenarios and climate impacts on forest variables indicative of ecosystem services related to timber, habitat, water, and carbon. The ecosystem services are represented through nine model output variables (timber harvest, above and belowground biomass, net ecosystem production, soil carbon, percolation, nitrogen leaching, deadwood, tree dimension, broadleaf tree proportion) from the process-based forest model 4C. We simulated forest growth, carbon and water cycling until 2045 with 4C set-up for the whole German forest area based on National Forest Inventory data and driven by three management strategies (nature protection, biomass production and a baseline management) and an ensemble of regional climate scenarios (RCP2.6, RCP 4.5, RCP 8.5). We provide results as relative changes compared to the baseline management and observed climate. Forest management measures have the strongest effects on ecosystem services inducing positive or negative changes of up to 40% depending on the ecosystem service in question, whereas climate change only slightly alters ecosystem services averaged over the whole forest area. The ecosystem services ‘carbon’ and ‘timber’ benefit from climate change, while ‘water’ and ‘habitat’ lose. We detect clear trade-offs between ‘timber’ and all other ecosystem services, as well as synergies between ‘habitat’ and ‘carbon’. When evaluating all ecosystem services simultaneously, our results reveal certain interrelations between climate and management scenarios. North-eastern and western forest regions are more suitable to provide timber (while minimizing the negative impacts on remaining ecosystem services) whereas southern and central forest regions are more suitable to fulfil ‘habitat’ and ‘carbon’ services. The results provide the base for future forest management optimizations at the regional scale in order to maximize ecosystem services and forest ecosystem sustainability at the national scale.

In this study, the overall utility of forest management alternatives at the forest management unit level is evaluated with regard to multi-purpose and multi-user settings by a multi-criteria analysis (MCA) method. The MCA is based on an additive utility model. The relative importance of partial objectives of forest management (carbon sequestration, ground water recharge, biodiversity, and timber production) is defined in cooperation with stakeholders. The forest growth model 4C (Forest Ecosystems in a Changing Environment) is used to simulate the impact of six forest management strategies and climate on forest functions. Two climate change scenarios represent uncertainties with regard to future climatic conditions. The study is based on actual forest conditions in the Kleinsee management unit in east Germany, which is dominated by Scots pine ( Pinus sylvestris L.) and oak ( Quercus robur L. and Quercus petraea Liebl.) stands. First, there is an analysis of the impact of climate and forest management on forest functions. Climate change increases carbon sequestration and income from timber production due to increased stand productivity. Secondly, the overall utility of the management strategies is compared under the priority settings of different stakeholder groups. From an ecological perspective, a conservation strategy would be preferable under all climate scenarios, but the business as usual management would also fit the expectations under the current climate due to high biodiversity and carbon sequestration in the forest ecosystem. In contrast, a forest manager in public-owned forests or a private forest owner would prefer a management strategy with an intermediate thinning intensity and a high share of pine stands to enhance income from timber production while maintaining the other forest functions. [ABSTRACT FROM AUTHOR]

Abstract: The model-based analysis of the effects of management options at stand and regional levels on forest functions such as carbon storage and groundwater recharge provides a basis for optimisation of forest planning under global change. The physiologically based model 4C (‘FORESEE’—FORESt Ecosystems in a changing Environment) can be used to evaluate a broad variety of silvicultural treatments for mono- and mixed-species forest stands. In this study, we present the testing and evaluation of the 4C management submodel, using data from long-term experimental plots in selected stands in the Federal State of Brandenburg, Germany. Comparison of experimental data with model simulations, by means of diameter distributions, demonstrated that the applied thinning operations preserved the diameter distribution of the stands. 4C realistically described the effects of management options on stand dynamics as proved by long-term simulations. Furthermore, the investigation of the effects of management options, thinning intensity, and rotation length on carbon storage in biomass and soil, yield, and groundwater recharge showed the applicability of the model 4C for the evaluation of forest functions in managed forests. We present the analysis of management effects on forest functions at a regional scale, based on a grid of forest monitoring sites (“Ökologische Waldzustandskontrolle”—ÖWK) in Brandenburg, which is mainly dominated by Scots pine (Pinus sylvestris L.). The model was applied at the sites with three management options under current climate and a climate change scenario (i.e., temperature increase of 1.4°K by 2055). The results of 50-year simulation runs were analysed for forest growth units with respect to total carbon storage (C sum) and groundwater recharge. More intensive management decreased the C sum after 50 years and slightly increased groundwater recharge. Climate change led to a reduction of groundwater recharge by about 40%, averaged over all sites. C sum was increased at some sites because of the extension of the growing season in spite of slight decreases in precipitation, but at several other sites, C sum decreased due to increased dryness. The question arises whether these negative effects of climate change can be minimised by adaptive management operations. In this study, we concluded that the potentials of adaptive management based on changes in rotation length and thinning is very limited in this region, which is characterised by poor sites and dry climatic conditions. We concluded that it is necessary to include forest transformation strategies in management impact analyses for forest planning under global change. [Copyright &y& Elsevier]