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

Climate impacts on environmental systemsFigure 3.14 Qualitative impacts of climatic and biotic variables on temperate mineral soilsExpected impacts of climate change on mineral soilsIncreasedatmosphericCO 2WarmingDrierWetterIncreasedNPPIncreasedNPPDecreaseNPPIncreasedNPPIncreased litter /SOM productionIncreased litter /SOM productionIncreaseddecompositionDecreased litter /SOM productionIncreased litter /SOM productionIncreased soilwater levelsIncreasedmicrobial activityIncreasedmineralisationIncreasedmineralisationReduceddecomposition> SOC> SOC < SOC < SOC > SOCIncreased soilrespirationDecreased litter /Increased soilSOM productionrespirationIncreasedcultivation> CO 2< SOC> CO 2Increased soilrespirationReduceddecomposition> SOC> CO 2> CH 4Increasederosion< SOC< SOCNote:SOC: soil organic carbon; SOM: soil organic matter; NPP: net primary productivity; CO 2: carbon dioxide; CH 4: methane.Decomposition is the post-mortem breakdown of organic matter into constituent elements or secondary substances throughchemical reactions and biological activity. Mineralisation is the conversion of an element from an organic to an inorganic stateas a result of microbial activity.Box 3.4The impacts of climate change on soil biota and biodiversitySoil biodiversity is vulnerable to impacts of climate change on terrestrial systems. However, quantifying thepossible effects is problematic given the difficulties in measuring, mapping and monitoring soil biotic communities.A recent meta-analysis of responses of soil biota to global change, based on manipulative experiments(Blankinship et al., 2011), noted that rising CO 2concentration will positively affect microflora and -fauna, whilemesofauna tend to respond negatively. The effect of the amount of precipitation is positively correlated withthe abundance of soil biota, but differs between ecosystems (soil biota abundance affected in forests, but not ingrasslands or heathlands). Warming will negatively affect the abundance of soil biota in sites characterised by lowmean annual temperature and mean annual precipitation (see Figure 3.14).There is some preliminary evidence that species are migrating to previously colder regions owing to warmertemperatures and an earlier start to spring. In mountainous regions, where evidence suggests that the tree line ismigrating upwards, we can assume that the below-ground ecoregions will follow since soil biota are intimately tiedto plant communities (Sylvain and Wall, 2011). However, the amount of habitat for those species adapted to livingabove the tree line will become reduced as the mountain summits provide an upper limit to the amount of verticalmigration that can occur. Observations and quantifications of this vertical migration for vascular plants have foundmigration rates of between 1 and 4 vertical metres every 10 years. Rates for soil biota are expected to be similar.150 Climate change, impacts and vulnerability in Europe 2012