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

Climate impacts on environmental systems3.4.2 Plant and fungi phenologyRelevancePhenology is the timing of seasonal events suchas budburst, flowering, dormancy, migration andhibernation. Some phenological responses aretriggered by mean temperature (Urhausen et al.,2011), while others are more responsive to daylength (Menzel et al., 2006) or weather extremes(Menzel et al., 2011). Changes in phenology affectthe growing season and thus ecosystem functioningand productivity. Changes in phenology areimpacting farming (see Section 4.1), forestry (seeSection 4.2), gardening and wildlife. The timingof tilling, sowing and harvesting is changing,fruit is ripening earlier due to warmer summertemperatures (Menzel et al., 2006), and grass inmunicipal parks and on road verges requires morefrequent cutting over a longer period. Changesin flowering have implications for the timingand intensity of the pollen season and relatedhealth effects (see Section 4.1). The pollen seasonis advancing as many species start to flowerearlier, and the concentration of pollen in the air isincreasing (Buters et al., 2010). The increasing trendin the yearly amount of airborne pollen for manytaxa is more pronounced in urban than semi-naturalareas across the continent (Ziello et al., 2012).Past trendsCompared to the 2008 report (EEA, 2008), there isnew evidence of climate change impacts on plantand fungi phenology. An analysis of 315 species offungi in England showed that these have increasedtheir fruiting season from 33 to 75 days between1950 and 2005 (Gange et al., 2007). Furthermore,climate warming and changes in the temporalallocation of nutrients to roots seem to have causedsignificant numbers of species to begin fruitingin spring as well as autumn. A study on 53 plantspecies in the United Kingdom found that theyhave advanced leafing, flowering and fruitingon average by 5.8 days between 1976 and 2005(Thackeray et al., 2010). Similarly, 29 perennial plantspecies in Spain have advanced leaf unfolding onaverage by 4.8 days, first flowering by 5.9 days,and fruiting by 3.2 days over the period 1943–2003,whereas leaf senescence was delayed on averageby 1.2 days (Gordo and Sanz, 2006a). For plants, amedium spring advancement of four to five days per1 °C increase has been observed in Europe (Bertin,2008; Estrella et al., 2009; Amano et al., 2010) (seeMap 3.11).Short warm and cold spells also can have a strongeffect on phenological events but this dependsstrongly on their timing and the species (Kochet al., 2009; Menzel et al., 2011). Continental-scalechange patterns have been derived from time seriesof satellite measured phenological variables(1982–2006) (Ivits et al., 2012). North-east Europeshowed a trend to an earlier and longer growingseason, particularly in the northern Baltic areas.Despite the earlier greening up, large areas ofEurope exhibited rather stable season lengthindicating the shift of the entire growing seasonto an earlier period. The northern Mediterraneandisplayed a growing season shift towards laterdates while some agglomerations of earlier andshorter growing season were also seen. Thecorrelation of phenological time series with climatedata shows a cause-and-effect relationship overthe semi-natural areas. In contrast, managedecosystems have a heterogeneous change patternwith less or no correlation to climatic trends. Overthese areas climatic trends seemed to overlapin a complex manner with more pronouncedeffects of local biophysical conditions and/or landmanagement practices.Key messages: 3.4.2 Plant and fungi phenology• The timing of seasonal events in plants is changing across Europe, mainly due to changes in climateconditions. Seventy-eight per cent of leaf unfolding and flowering records show advancing trends inrecent decades whereas only 3 % show a significant delay. Between 1971 and 2000, the averageadvance of spring and summer was between 2.5 and 4 days per decade.• As a consequence of climate-induced changes in plant phenology, the pollen season starts on average10 days earlier and is longer than it was 50 years ago.• Trends in seasonal events are projected to advance further as climate warming proceeds.Climate change, impacts and vulnerability in Europe 2012131