Ensemble analysis of frost damage on vegetation caused by spring backlashes in a warmer Europe

Abstract

Abstract. Tree dehardening and budburst will occur earlier in a warmer climate, and this could lead to an increased risk of frost damage caused by temperature backlashes. By using a spring backlash index and a cold hardiness model, we assessed different aspects of risk for frost damage in Norway spruce forests during the present climate and for one future emission scenario. Uncertainties associated with climate modelling were quantified by using temperature data from three climate data sets: (1) E-Obs gridded observed climate data, (2) an ensemble of data from eight regional climate models (RCM) forced by ERA-40 reanalysis data, (3) an ensemble of regional climate scenarios produced by the regional climate model RCA3 driven at the boundary conditions by seven global climate models (GCM), all representing the SRES A1B emission scenario.The frost risk was analysed for three periods, 1961-1990, 2011-2040 and 2070-2097. The RCA3 GCM ensemble indicated that the risk for spring frost damage may increase in the boreo-nemoral forest zone of southern Scandinavia and the Baltic states/Belarus. This is due to an increased frequency of backlashes, lower freezing temperatures after the onset of the vegetation period and the last spring frost occurring when the trees are closer to budburst. The changes could be transient due to the fine balance between an increased risk of frost damage caused by dehardening during a period when freezing temperatures are common and a decreased risk caused by warmer temperatures. In the nemoral zone, the zone with highest risk for spring backlashes during the reference period , the spring frost severity may increase due to frost events occurring when the trees are closer to budburst. However, the risk in terms of frequency of backlashes and freezing temperature were projected to become lower already in the beginning of this century.Correspondence to: A. M. Jönsson

Trends and uncertainties in budburst projections of Norway spruce in Northern Europe

“…The results of this study indicated that the temporal differences in timing of budburst between early and late provenances will remain in a warmer climate; however, the magnitude of temperature change will influence the regions and provenances most at risk. This is due to the fine balance between warmer climate generally reducing the number of frost days and tree dehardening and budburst occurring earlier in the year, at a time when temperature backlashes are more frequent (Jönsson & Bärring, ). While it was beyond the scope of this study to assess the risk of frost damage, it pointed toward the need of analyzing both the general trend in timing of budburst (most pronounced in northern Europe) and the interannual variation (will increase most in western Europe), as both aspects influence the risk.…”

“…Potential implications that may follow from phenological shifts in trees include longer growing seasons, which may increase forest productivity (Richardson et al, 2010). However, as frost hardiness in spring is negatively related to growth activity (Westin, Sundblad, Strand, & Hällgren, 2000), an earlier onset of the growing season may increase the risks and severity of frost damage during late spring cold spells (Jönsson & Bärring, 2011). For commercially important species like Norway spruce, for which large differences in phenology traits exist among provenances, comprehensive cultivation research is carried out to identify traits favorable in a warmer climate (e.g., Skrøppa & Steffenrem, 2016;Westin et al, 2000).…”

Winter survival and deacclimation of perennials under warming climate: physiological perspectives

“…There is a risk that some regions are likely to experience severe reductions in available winter chill, potentially preventing endodormancy release in some perennials (Luedeling et al 2011). Early onset of spring phenology can increase the risk of tissue damage by subsequent frosts, the likelihood of which is typically high during the early spring (Saxe et al 2001, Jönsson and Bärring 2011).…”

Spatial and temporal variability of the frost‐free season in Central Europe and its circulation background

“…Variations in minimum air temperature, length of the frost-free season (FFS), as well as the timing of frost events are not reflected in a simple analysis of main climate elements (Robeson, 2002;Jönsson and Bärring, 2011). All three characteristics are economically important, and are studied extensively in Europe and throughout the world (Robeson, 2002;Fernández-Long et al, 2013;Winkler et al, 2013;Yu et al, 2014).…”