| Text | 316344 2014 Foreste The condition of forests in Europe. Executive report 2013 Walter Seidling; Tanja Sanders; Cecilia Akselsson; Nathalie Cools; Alessandra De Marco; Bruno De Vos; Wim De Vries; Sophia Etzold; Marco Ferretti; Uwe Fischer; Paolo Giordani; Elisabeth Graf Pannatier; Karin Hansen; Mathieu Jonard; Aldo Marchetto; Radovan Nevenic; Pasi Rautio; Gert Jan Reinds; Mitja Skudnik; Svein Solberg; Laura Martinez Suz; Lisa Ukonmaanaho; Elena Vanguelova; Stavros Veresoglou; Peter Waldner; Esther Wattel Koekkoek; Daniel Zlindra; Richard Fischer Seidling, Walter Thunen Institute of Forest Ecosystems, D 16225 Eberswalde, Germany; Sanders, Tanja Thunen Institute of Forest Ecosystems, D 16225 Eberswalde, Germany; Akselsson, Cecilia University of Lund; Cools, Nathalie The Research Institute for Nature and Forest INBO ; De Marco, Alessandra ENEA; De Vos, Bruno The Research Institute for Nature and Forest INBO ; De Vries, Wim Alterra Green World Research, Wageningen, The Netherlands; Etzold, Sophia WSL, Swiss Federal Institute for Forest, Snow and Landscape Research, Zurcherstrasse 111, CH 8903 Birmensdorf, Switzerland; Ferretti, Marco terradata environmetrics; Fischer, Uwe Thunen Institute for International Forestry and Forest Economics, Leuschnerstrasse 91, D 21031 Hamburg, Germany; Giordani, Paolo Universita di Genova; Graf Pannatier, Elisabeth WSL, Swiss Federal Institute for Forest, Snow and Landscape Research, Zurcherstrasse 111, CH 8903 Birmensdorf, Switzerland; Hansen, Karin IVL Swedish Environmental Research Institute, SE 100 31 Stockholm, Sweden; Jonard, Mathieu Universite catholique de Louvain; Marchetto, Aldo CNR ISE, Pallanza Verbania; Nevenic, Radovan Institute of Forestry, Belgrade, Serbia; Rautio, Pasi METLA, Finnish Forest Research Institute, PL 18, FI 01301 Vantaa, Finland; Reinds, Gert Jan Alterra Green World Research, Wageningen, The Netherlands; Skudnik, Mitja Slovenian Forestry Institute, SI 1000 Ljubljana, Sloveni; Solberg, Svein Norwegian forest and landscape institute NFLI ; Martinez Suz, Laura Royal Botanic Gardens, Kew Richmond, Surrey; Ukonmaanaho, Lisa METLA, Finnish Forest Research Institute, PL 18, FI 01301 Vantaa, Finland; Vanguelova, Elena Forest Research, Alice Holt Lodge, Wrecclesham, Farnham, Surrey GU10 4LH, United Kingdom; Veresoglou, Stavros Freie Universitat Berlin; Waldner, Peter WSL, Swiss Federal Institute for Forest, Snow and Landscape Research, Zurcherstrasse 111, CH 8903 Birmensdorf, Switzerland; Wattel Koekkoek, Esther Netherlands National Institute for Public Health; Zlindra, Daniel Slovenian Forestry Institute, SI 1000 Ljubljana, Sloveni; Fischer, Richard Thunen Institute for International Forestry and Forest Economics, Leuschnerstrasse 91, D 21031 Hamburg, Germany Just over three quarters 78% of the atmosphere comprises inert nitrogen which has very limited availability for biological use. All terrestrial ecosystems need reactive nitrogen and historically this has been in short supply. Artificial nitrogenous fertilizers and fossil fuel combustion are both sources of reactive nitrogen and their use has dramatically altered the global nitrogen cycle. 1. ATMOSPHERIC DEPOSITION Nitrogen deposition largely originates from fossil fuel combustion and animal husbandry. Deposition is highest in central Europe. Only a minor decrease in deposition has been measured on intensive monitoring plots over the past decade. 2. LICHENS Lichens are very sensitive indicators of nitrogen deposition. Deposition is high on 75% of the European forest plots and this is reflected in the change in lichen species composition over time. 3. MOSSES Mosses absorb most of their nutrients and water across their surface. As a result, they are directly affected by atmospheric deposition. In a study carried out in Austria, Croatia, Italy, and Slovenia the nitrogen content in mosses significantly increased with increasing nitrogen deposition see p. 10 . 4. FUNGI Fungal species diversity and structure significantly decrease with increasing nitrogen deposition. On a European transect through nine countries, 393 mycorrhizal species were determined. These fungal types live in symbiosis with tree roots and play a major role in nutrient uptake by trees see p. 12 . 5. SOIL SOLUTION An analysis of trends on the Level II plots showed exceedances of critical limits for nitrogen in the subsoil on 50% of the plots. Leaching is mainly dependent on nitrogen deposition with other factors playing a relatively minor role. 6. LITTERFALL Litterfall and its decomposition are critical processes for transferring nutrients from above ground forest biomass to soils. Tree species composition and thus foliar litter chemistry affects nitrogen cycling rates at the scale of entire forest stands; for example, the scale of the nitrogen transfer in litterfall determines the amount of nitrogen available for tree growth. 7. SOIL SOLID PHASE Soils play a key role in nitrogen cycling and storage within ecosystems. They host nitrogen fixing microorganisms, as well as those that release nitrogen back into the air. Mineralization of organically bound nitrogen takes place within soils and converts nitrogen to a form available for tree growth. Loss of nitrogen from the soil is mainly through harvesting and leaching. One of the key questions concerns the saturation status of European forest soils. 8. GROUNDWATER QUALITY Rain water containing dissolved nitrogen is pulled downwards through the soil by gravity, this is known as leaching. Leaching may affect the quality of drinking water pumped up from groundwater. In forests on sandy soils in the Netherlands nitrogenleaching has decreased by 55% over the past 20 years, showing the success of emission reduction policies. 9. EFFECTS ON TREES 9A FOLIAGE NUTRIENT BALANCE Soil nitrogen generally stimulates plant growth. However, excess nitrogen can cause other nutrients such as magnesium to become deficient. This can affect forest health and enhance the effects of additional stress factors. Nutrient im balances were detected in leaves and needles on 10% of the nitrogen saturated plots. 9B CROWN CONDITION TREE HEALTH Effects of nitrogen deposition on leaf and needle loss can be detected at a local level for some tree species. These impacts are compounded by the effects of weather, insects and diseases, and soil condition. 9C STEM GROWTH Nitrogen acts as fertilizer for trees. At sites with low nitrogen soil levels, atmospheric nitrogen inputs increase growth. But on nitrogen saturated plots, even high atmospheric nitrogen inputs have no impact on tree growth. 10. CONCLUSIONS Assessing the input of nitrogen to forests and the direct and indirect responses of forest trees are core activities of the large scale and intensive monitoring of forest ecosystems in Europe. ICP Forests provides policy makers with key information for forest management, especially under the projected future climatic changes. http //www.icp forests.org/pdf/ER2013.pdf ID_PUMA cnr.ise/2014 TR 003. 2013 Executive report 36 pp. The condition of forests in Europe. Executive report 2013 2014_TR_003.pdf Rapporto tecnico aldo.marchetto MARCHETTO ALDO TA.P02.014.002 Impatto dei cambiamenti globali sugli ecosistemi acquatici |
