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

Climate impacts on environmental systemsconcentrations due to reduced dilution (Whiteheadet al., 2009), whereas increases in floods and extremeprecipitation events can increase the nutrient load tosurface waters due to increased surface run-off anderosion, (Fraser et al., 1999; Battarbee et al., 2008).In this context, it should be noted that significantmanagement changes can have much larger impactson nutrient concentrations than climatic changes(Bryhn et al., 2010).Increases in soil temperature, moisture and intensiverainfall can enhance the concentrations of dissolvedorganic matter (DOC) (Worrall et al., 2002; Soulsbyet al., 2003; Inamdar et al., 2006; Roulet and Moore,2006). Increased DOC concentration has beenobserved in lakes and streams in Europe and NorthAmerica in recent decades, primarily due to arecovery from acid deposition, but climate changemay result in additional increases (Monteith et al.,2007). The overall relationship between climatechange and DOC concentrations is not clear due tothe importance of different processes with opposingeffects (Epp et al., 2007; Futter et al., 2007). Enhancednutrient and DOC concentrations can give increasedeutrophication, lower oxygen levels and poorerunderwater light conditions.Algal blooms and water qualityClimate change can enhance harmful algal blooms inlakes, both as a direct result of temperature increaseand as a result of climate-induced increases innutrient concentrations. Increased lake temperaturewill generally have a eutrophication-like effect(Schindler, 2001), with enhanced phytoplanktonblooms (Wilhelm and Adrian, 2008), and increaseddominance of cyanobacteria in phytoplanktoncommunities. These changes may restrain the useof lake drinking water and recreation and they mayincrease the associated health risks (Mooij et al.,2005; Jöhnk et al., 2008; Paerl and Huisman, 2008).Phytoplankton and zooplankton blooms in severalEuropean lakes are now occurring one monthearlier than 30–40 years ago, giving rise to thepotential for a trophic mismatch between bloomspecies and other species (Weyhenmeyer et al., 1999;Weyhenmeyer, 2001; Adrian et al., 2006; Nõges et al.,2010).3.4 Terrestrial ecosystems andbiodiversity3.4.1 OverviewClimate change affects individual organisms(e.g. plant, fungi and animal species), wholeecosystems and their services in many ways. Thedirect effects of climate change, such as changes inspecies phenology and distribution, are moderatedby impacts on the habitat and by ecologicalinteractions between species, such as competitionand food webs (see Figure 3.12). Furthermore,climate change usually does not act in isolation buttogether with other factors, such as eutrophicationand human land use and management. Theprincipal response mechanisms of species toclimate change depend on their adaptive capacityand include phenological and/or physiologicaladaptation, migration and colonisation of newhabitats. All these mechanisms face importantconstraints in terms of timing and/or effectiveness.Key messages: 3.4 Terrestrial ecosystems and biodiversity• The timing of seasonal events in plants and animals is changing across Europe. Between 1971 and2000, phenological events in spring and summer have advanced on average between 2.5 and 4 daysper decade. The pollen season today starts on average 10 days earlier and is longer than it was50 years ago. Climate change is regarded as the main cause of these changes.• Breeding seasons of thermophilic insects such as butterflies, dragonflies and bark beetles arelengthening, allowing for extra generations to be produced during the year.• Many European plant and animal species have shifted their distribution northward and uphill in responseto observed climate change.• The rate of climate change is expected to exceed the ability of many species to adapt and migrate,especially where landscape fragmentation may restrict movement.• Direct effects on single species are likely amplified by species interactions, such as disruption of presentfood webs.• Almost one fifth of habitats and 12 % of species of European interest are potentially threatened byclimate change over their natural European range. Bogs, mires and fens are considered to be the mostvulnerable habitat types.Climate change, impacts and vulnerability in Europe 2012127