Spatial Difference of Interactive Effect Between Temperature and Daylength on Ginkgo Budburst

Abstract

Climate warming-induced shifts in spring phenology have substantially affected the structure and function of terrestrial ecosystems and global biogeochemical cycles. Spring phenology is primarily triggered by spring temperature and is also affected by daylength and winter chilling, yet the relative importance of these cues across spatial gradients remains poorly understood. Here, we conducted a manipulative experiment with two daylength and three temperature treatments to investigate spatial differences in the response of ginkgo budburst to temperature and daylength, using twigs collected at three sites across a spatial gradient: a control site at a low latitude and low elevation on Tianmu Mountain (TMlow), a low latitude and high elevation site on Tianmu Mountain (TMhigh), and a high latitude site on Jiufeng mountain (JF). The mechanisms were also tested using in situ phenological observations of ginkgo along latitudes in China. We found that, compared to TMlow individuals, budburst dates occurred 12.6 (JF) and 7.7 (TMhigh) days earlier in high-latitude and high-elevation individuals when exposed to the same temperature and daylength treatments. Importantly, daylength only affected budburst at low latitudes, with long days (16 h) advancing budburst in low-latitude individuals by, on average, 8.1 days relative to short-day (8 h) conditions. This advance was most pronounced in low-elevation/latitude individuals (TMlow = 9.6 days; TMhigh = 6.7 days; JF = 1.6 days). In addition, we found that the temperature sensitivity of budburst decreased from 3.4 to 2.4 days °C−1 along latitude and from 3.4 to 2.5 days °C−1 along elevation, respectively. The field phenological observations verified the experimental results. Our findings provide empirical evidence of spatial differences in the relative effects of spring temperature and daylength on ginkgo budburst, which improved our understanding of spatial difference in phenological changes and the responses of terrestrial ecosystem to climate change.

Poleward shifts in the maximum of spring phenological responsiveness of Ginkgo biloba to temperature in China

“…Chilling and photoperiod limitation were nonlinearly correlated with MAT, and positively linearly correlated with MAP, consistent with the environmental gradients in phenological responsiveness. Previous studies have indicated that photoperiod limitation on spring leaf‐out increases with MAT, because decreases in chilling accumulation toward warmer regions will lead to higher photoperiod sensitivity (Zhang et al ., 2007; Zohner et al ., 2016; Wu et al ., 2022b). Our study now provides evidence that photoperiod limitation may also increase toward cold regions, where temperatures are regularly below the effective chilling temperature range.…”

“…In warm areas, the higher risk of late spring frosts (Zohner et al ., 2020a) may contribute to a decrease in RSP as a strategy to mitigate potential frost damage. To achieve this, trees adapted to warmer climates may exhibit greater sensitivity to photoperiod limitation, resulting in a lower RSP (Zohner et al ., 2016; Wu et al ., 2022b).…”

“…We monitored the development of buds for each twig every 3 d. The date of leaf‐out was defined as the date when the first bud scale had opened and the leaf was partially visible (Vitasse, 2013; Wu et al ., 2022b). We used the time to leaf‐out, defined as the number of days from the start of treatment to the leaf‐out date, to represent RSP, that is, the shorter the time to leaf‐out, the higher the RSP.…”

“…Despite a robust understanding of these overarching mechanisms that collectively determine leaf emergence in spring, it remains unclear whether, and how, the relative importance of each driver differs across broad spatial scales, which limits our capacity to predict regional variation in spring phenology. The lack of climate‐manipulation experiments at large spatial scales (Peaucelle et al ., 2019; Wu et al ., 2022b) limits our knowledge of the responsiveness of spring phenology (RSP) to environmental gradients and of the drivers of such variation. Full‐factorial experiments to identify spatial variation in the phenological responsiveness under varying climate conditions will be integral to improving our understanding of the responses of plants to climate change and to facilitating ecosystem conservation (Rosemartin et al ., 2014; Ettinger et al ., 2022; Walde et al ., 2022; Wolkovich et al ., 2022).…”

“…Therefore, manipulative experiments are necessary to identify the unifying mechanisms that can provide confidence in spatial predictions and overcome the spatial idiosyncrasies in previous studies. However, such experiments have been limited to narrow geographic ranges (Wu et al ., 2022b), and so we lack the data to disentangle the drivers of spring phenological changes across broad latitudinal gradients. To address this gap, we conducted a full‐factorial climate‐manipulation experiment on Ginkgo biloba L., a deciduous dioecious tree species, across a wide environmental gradient from subtropical to temperate regions (ranging from 24° to 44° latitude).…”