Effect of climate change on bud phenology of young aspen plants (Populus tremula. L)

Abstract

Boreal tree species are excellent tools for studying tolerance to climate change. Bud phenology is a trait, which is highly sensitive to environmental fluctuations and thus useful for climate change investigations. However, experimental studies of bud phenology under simulated climate change outdoors are deficient. We conducted a multifactorial field experiment with single (T, UVA, UVB) and combined treatments (UVA+T, UVB+T) of elevated temperature (T, +2°C) and ultraviolet‐B radiation (+30% UVB) in order to examine their impact on both male and female genotypes of aspen (Populus tremula L.). This study focuses on the effect of the treatments in years 2 and 3 after planting (2013, 2014) and follows how bud phenology is adapting in year 4 (2015), when the treatments were discontinued. Moreover, the effect of bud removal was recorded. We found that elevated temperature played a key role in delaying bud set and forcing bud break in intact individuals, as well as slightly delaying bud break in bud‐removed individuals. UVB delayed the bud break in bud‐removed males. In addition, both UVA and UVB interacted with temperature in year 3 and even in year 4, when the treatments were off, but only in male individuals. Axillary bud removal forced both bud break and bud set under combined treatments (UVA+T, UVB+T) and delayed both under individual treatments (T, UVB). In conclusion, male aspens were more responsive to the treatments than females and that effect of elevated temperature and UV radiation on bud set and bud break of aspen is not disappearing over 4‐year study period.

The influence of spectral composition on spring and autumn phenology in trees

“…In the same experiments described above, 30% UV-B-supplementation advanced autumnal bud set by 1 day in the first growing season (Strømme et al 2015), but again, there was no effect during the two subsequent years except when axillary buds were removed, suggesting that hormonal regulation by ABA or auxin could be involved in this response (Sivadasan et al 2017). Bud set in the first year of growth in the UVB-attenuation study, however, was advanced by 13 days under near-ambient UV-B compared with reduced UV-B radiation in Populus tremula at a high elevation site (830m a.s.l) but not at low altitude sites (237m and 575m a.s.l., Strømme et al 2018b).…”

“…In a modulated-UV-enhancement field experiment in Joensuu, Finland, Strømme et al (2018a), found that a supplemental UV-B treatment (30 % increase compared with ambient) received in the previous growing season advanced the bud-burst date by 2.0 days in male (but not female) Populus tremula saplings. This effect was significant, but varied considerably from year to year, over three years of growth in plants that were 1-4 years old (Sivadasan et al 2017, Strømme et al, 20152018a).…”

A perspective on ecologically relevant plant-UV research and its practical application

“…Furthermore, the question arises, why does UV-B radiation advance bud burst and flowering in some plant species, but delay phenology in others? 151,152 Is it possible that different species have evolved to respond differently to UV cues? Phenology is potentially critical for survival and fitness of plants, so answering these questions is important for understanding the interactions of UV-B and climate change parameters (Fig.…”

Severe frost but not shade could limit the future growing season of Erythronium americanum

“…In particular, these changes are affecting the timing of transitions between seasons, with spring temperatures arriving earlier than typical in some areas (Monahan et al, 2016;Christiansen, Markstrom and Hay, 2011). As a result, some species have altered the timing of their migrations (Gill et al, 2014;Somveille et al, 2020), flowering (CaraDonna, Iler, and Inouye, 2014; Bertin, D r a f t 2015), bud break (Sivadasan et al, 2017;Ladwig et al, 2019), and leaf senescence (Gallinat, Primack and Wagner, 2015;Wu et al, 2018).…”