Climate change, impacts and vulnerability in Europe ... - MemoFin.fr

Climate impacts on socio-economic systems and healthInformation on forest fires is collected in theEuropean Fire Database at the JRC. The Europeanforest fire database is an important component of theEuropean Forest Fire Information System (EFFIS).Forest fire data are provided each year by individualEU Member States through several EU regulations,and additional data coming from other Europeancountries have been checked, stored and managedby JRC within EFFIS. The quality of the data is high.A time series on forest fires exists back to 1980 forthe five European countries most affected by forestfires. Currently, the database covers data from22 countries in Europe and contains over 2 millionindividual fire event records.4.2.2 Forest growthRelevanceTree growth is controlled by complex interactionsbetween climate and non‐climate factors, withforest management having a significant effect.Trees have long been known to respond to changesin climate: variations in tree ring widths from oneyear to another are recognised as an importantsource of climatic information although difficult tointerpret. Climate change is expected to influenceforest composition and productivity (see Table 4.1).Increases in atmospheric CO 2, changes intemperature and the availability of water will affectthe relative health and productivity of differentspecies in complex ways. CO 2has a direct impact ontree function and forest productivity. An increasedconcentration in the atmosphere stimulatesphotosynthesis and likely results in an increasein growth rates and leaf area, if other factors arenot limiting. Increased temperatures generallyspeed up plant growth, rates of decompositionand nutrient cycling, though other factors likeavailability of water also influence these processes.Higher temperatures lengthen the growing seasonby advancing its start in spring and delaying its endin fall.Climate change is expected to present several threatsto forest growth and productivity such as increasedfrequency and severity of summer droughtwith impacts on drought-sensitive tree species,in particular on shallow, freely draining soils(Houghton, 2003; Melillo et al., 2011). Indirect effectson forest productivity are expected through changesto the frequency and severity of pest and diseaseoutbreaks, increasing populations of damaginginsects and mammals, and the impact of existingand new invasive species. Concurrent changes innitrogen and sulphur deposition and increasedlevels of ozone pollution are also expected to havean impact. Nitrogen deposition can stimulate forestgrowth but it can also increase the susceptibilityof trees to drought, diseases, pests and frost bycausing acidification and nutrient imbalances, thusdecreasing forest vitality. Based on the currentunderstanding of these processes, the individualeffects of climate and non‐climate changes aredifficult to disentangle.Past trendsSince the 20th century, the annual increment offorests in Europe (in terms of area and growingstock) has increased due to advances in forestmanagement practices, genetic improvement and,in central Europe, the cessation of site-degradingpractices. Abandoned farmland in high and midlatitudes is reverting to forest, which store muchmore carbon than the previous cropland.Forests and other wooded land cover approximately190 million ha (1.9 million km 2 ) in the EEA region,and this area has increased over the last decades(Forest Europe, UNECE and FAO, 2011). Forestbiomass has also grown over the past two decades,Key messages: 4.2.2 Forest growth• The area covered by forests and other wooded land in Europe (39 EEA countries) has increased formany decades.• Forest biomass in the EEA region is growing, and the average growth rate has increased from 1990 to2010.• In some central and western areas of Europe, forest growth has been reduced in the last 10 years dueto storms, pests and diseases.• Future climate change and increasing CO 2concentrations are expected to affect site suitability,productivity, species composition and biodiversity, and thus have an impact on the goods and servicesthat the forests provide. In general, forest growth is projected to increase in northern Europe and todecrease in southern Europe.174 Climate change, impacts and vulnerability in Europe 2012