Long‐term changes in the impacts of global warming on leaf phenology of four temperate tree species

Abstract

Contrary to the generally advanced spring leaf unfolding under global warming, the effects of the climate warming on autumn leaf senescence are highly variable with advanced, delayed, and unchanged patterns being all reported. Using one million records of leaf phenology from four dominant temperate species in Europe, we investigated the temperature sensitivities of spring leaf unfolding and autumn leaf senescence (ST, advanced or delayed days per degree Celsius). The ST of spring phenology in all of the four examined species showed an increase and decrease during 1951–1980 and 1981–2013, respectively. The decrease in the ST during 1981–2013 appears to be caused by reduced accumulation of chilling units. As with spring phenology, the ST of leaf senescence of early successional and exotic species started to decline since 1980. In contrast, for late successional species, the ST of autumn senescence showed an increase for the entire study period from 1951 to 2013. Moreover, the impacts of rising temperature associated with global warming on spring leaf unfolding were stronger than those on autumn leaf senescence. The timing of leaf senescence was positively correlated with the timing of leaf unfolding during 1951–1980. However, as climate warming continued, the differences in the responses between spring and autumn phenology gradually increased, so that the correlation was no more significant during 1981–2013. Our results further suggest that since 2000, due to the decreased temperature sensitivity of leaf unfolding the length of the growing season has not increased any more. These finding needs to be addressed in vegetation models used for assessing the effects of climate change.

Climate change fingerprints in recent European plant phenology

“…Kolářová, Nekovář, & Adamík, ). In this respect our paper disagrees with the findings of Chen et al (), likely because species other than trees were also incorporated in our spring signal. In contrast, the FS was shortened by −0.15 days/year due to a smaller advancing trend in farmers’ spring activities than in the development of wild plant species, matching the previous findings of Estrella et al ().…”

“…Out of the complete phenological data from these countries, For data correction (following e.g. Chen et al, 2018Chen et al, , 2019Ma, Huang, Hänninen, & Berninger, 2019;Vitasse, Signarbieux, & Fu, 2018), we filtered out in each series those observations outside the range median ± 3.5 × MAD (median absolute deviation), which is definitely a more than conservative approach (see Leys, Ley, Klein, Bernard, & Licata, 2013;Miller, 1991), since only the extreme values considered absolutely wrong were excluded (in our case less than 0.7% of the data).…”

“…Güsewell, Furrer, Gehrig, and Pietragalla () showed that for Switzerland there are still no indications of a lack of chilling leading to altered temperature sensitivities. Changes in temperature sensitivities are reported as not uniform over time (Chen et al, ) and, in particular, a weakened temperature response was observed since 2000 (Fu et al, ). Spatial variations in temperature sensitivity have been linked to mean annual temperature and to seasonal temperature range (Lapenis, Henry, Vuille, & Mower, ; Menzel, Sparks, Estrella, & Roy, ; Wang et al, ).…”

Greater capacity to exploit warming temperatures in northern populations of European beech is partly driven by delayed leaf senescence

“…The significant carry-over effect of BB on LS timing that we found is consistent with other recent studies on beech (Fu et al 2014; Signarbieux et al 2017; Chen et al 2018; Zohner and Renner 2019), and other deciduous trees across the northern hemisphere (Keenan and Richardson 2015; Liu et al 2016b). However, it can be difficult to disentangle the effects of temperature on both BB and LS, from their interdependency.…”

“…For instance, BB is more affected by photoperiod in colder populations, and by chilling requirements in warmer populations (Gárate-Escamilla et al 2019). Studies of LS in beech suggest that: (i) temperature may be a more important cue than photoperiod when nutrients and water are not limiting (Fu et al 2018); (ii) non-senescent green leaves are prematurely lost as a result of severe drought conditions (Bréda et al 2006); (iv) early BB correlates with early LS (Fu et al 2014; Chen et al 2018; Zohner et al 2018); (v) leaves first start to change color in autumn from the upper part of the canopy, suggesting that hydraulic conductance or the amount of solar radiation received over the growing season may play a role in triggering LS (Gressler et al 2015; Lukasová et al 2019), although this could also be related to an hormonal effect (Zhang et al 2011).…”