Nutrient availability alters the correlation between spring leaf-out and autumn leaf senescence dates

Abstract

Leaf senescence (LS) affects tree fitness, species distribution and ecosystem structure and functioning. The drivers of LS and the processes underlying it have been studied, but the studies have mainly focused on environmental cues and have mainly been based on statistical analyses using in situ data sets. Experimental investigation and field verification of the processes and drivers are thus urgently needed. We conducted a nutrient-addition experiment after a spring-warming experiment in which an ~40-day range of leaf-out (LO) dates was induced in horse chestnut (Aesculus hippocastanum) and beech (Fagus sylvatica) saplings. We found that both increased nutrient supply and advanced LO date significantly affected the timing of LS, but their effects were opposite, as the former delayed and the latter advanced the senescence. The effects of nutrient supply and LO interacted species specifically. In chestnut, the delay of senescence caused by fertilization increased with the delay of LO and was thus stronger for individuals that flushed late in the spring. On the contrary, in beech the delay of senescence caused by fertilization decreased with the delay of LO and was insignificant for individuals with the latest LO. The experimental findings for beech were confirmed with mature trees at a regional scale. The interactive effect between nutrients and LO on senescence may be associated with variable sensitivity to photoperiod, growth sink limitation and/or direct effect of foliar nutrition on the timing of senescence. Our novel results show that the interactive effects of LO and nutrient supply on the timing of LS should be further addressed experimentally in forthcoming studies. It would also be interesting to consider our results in the further development of phenological models used in assessing the effects of climatic change. The differences found in the present study between horse chestnut and beech suggest that the results found for one species cannot necessarily be generalized to other species, so studies with different temperate tree species are called for.

Decreasing control of precipitation on grassland spring phenology in temperate China

“…Linear regression was also used to investigate the changes in the climate factors from December to the mean date of the SOS during the entire 1982–2015 study period. To examine the effects of temperature on the timing of the SOS, we determined the most temperature‐relevant periods (preseason) for the SOS using partial correlation analysis (Fu, Piao, et al, 2019). To determine the primary climatic factor, either precipitation or temperature, affecting SOS timing during the whole period of 1982–2015 and the two subperiods (1982–1998 and 1999–2015), we used partial correlation to remove the compound effect (Fu, Zhao, et al, 2015) and defined the main regulating factor of SOS date as the maximum of the absolute value of the partial correlation coefficient for each pixel.…”

Impact of microclimatic conditions and resource availability on spring and autumn phenology of temperate tree seedlings

“…The timing of autumn leaf senescence is strongly regulated by autumn temperature and photoperiod in many temperate tree species (Keskitalo et al ., 2005 ; Vitasse et al ., 2009 ; Fu et al ., 2018 ). However, spring and summer photosynthesis (Zani et al ., 2020 ), CO 2 concentration (Sigurdsson, 2001 ), soil nutrient status (Weih & Karlsson, 1999 ; Sigurdsson, 2001 ; Estiarte & Peñuelas, 2015 ; Fu et al ., 2019a , 2019b , 2019a , 2019b ) and water availability (Xie et al ., 2015 ; Arend et al ., 2016a , 2016b , 2016a , 2016b ) can have a large influence as well. These factors have often been studied in situ , not accounting for micro‐environmental heterogeneities, but they have rarely been studied under experimental conditions (but see e.g.…”

How changes in spring and autumn phenology translate into growth‐experimental evidence of asymmetric effects

“…Apart from day‐length effects, physiological constraints resulting from sink limitation also lead to a downregulation of photosynthesis in autumn (Kumar et al., 2019). Because the seasonal sink capacity of plants is limited, for instance by nutrient supply (Y. H. Fu et al., 2019), sink strength is gradually decreasing towards autumn as the demand for growth is declining (Kuptz et al., 2011). The limiting effect of sink capacity on autumn productivity and phenology has recently been demonstrated by experimental and observational work, showing that increasing spring and summer productivity advance autumn growth cessation and senescence (Fu et al., 2014; Lim et al., 2007; Zani et al., 2020; Zohner & Renner, 2019; Zohner et al., 2019).…”

“…Autumn productivity therefore appears to be limited by plant's carbon sink strength (e.g. nutrient limitation), despite warmer conditions (Fu et al., 2014, 2019; Keenan & Richardson, 2015; Lim et al., 2007; Woo et al., 2019; Zani et al., 2020; Zohner et al., 2019). Because the magnitude of these effects on overall autumn growth is not well‐understood, experimental studies disentangling the relative roles of phenology and climate during the growing season are needed.…”