Temperature alone does not explain phenological variation of diverse temperate plants under experimental warming

Abstract

Anthropogenic climate change has altered temperate forest phenology, but how these trends will play out in the future is controversial. We measured the effect of experimental warming of 0.6-5.0 °C on the phenology of a diverse suite of 11 plant species in the deciduous forest understory (Duke Forest, North Carolina, USA) in a relatively warm year (2011) and a colder year (2013). Our primary goal was to dissect how temperature affects timing of spring budburst, flowering, and autumn leaf coloring for functional groups with different growth habits, phenological niches, and xylem anatomy. Warming advanced budburst of six deciduous woody species by 5-15 days and delayed leaf coloring by 18-21 days, resulting in an extension of the growing season by as much as 20-29 days. Spring temperature accumulation was strongly correlated with budburst date, but temperature alone cannot explain the diverse budburst responses observed among plant functional types. Ring-porous trees showed a consistent temperature response pattern across years, suggesting these species are sensitive to photoperiod. Conversely, diffuse-porous species responded differently between years, suggesting winter chilling may be more important in regulating budburst. Budburst of the ring-porous Quercus alba responded nonlinearly to warming, suggesting evolutionary constraints may limit changes in phenology, and therefore productivity, in the future. Warming caused a divergence in flowering times among species in the forest community, resulting in a longer flowering season by 10-16 days. Temperature was a good predictor of flowering for only four of the seven species studied here. Observations of interannual temperature variability overpredicted flowering responses in spring-blooming species, relative to our warming experiment, and did not consistently predict even the direction of flowering shifts. Experiments that push temperatures beyond historic variation are indispensable for improving predictions of future changes in phenology.

The shifting phenological landscape: Within‐ and between‐species variation in leaf emergence in a mixed‐deciduous woodland

“…For example, sessile oak ( Quercus petraea ) and European beech ( Fagus sylvatica ) show marked differences in their sensitivity to spring temperature, advancing their budburst date by 7.26 and 2.03 days per degree Celsius increase, respectively (Vitasse et al., 2009). Interspecific differences in spring phenology are thought to be largely a result of variation in the warming and chilling requirements between species (Marchin et al., 2015), as well as variation in sensitivity to nontemperature cues such as photoperiod. Indeed in some species, budburst is primarily controlled by photoperiod, with sensitivity to temperature only developing once a critical day length has been reached time (Basler & Körner, 2012).…”

“…Differences in cue sensitivity between species can often be explained by differences in physiology or ecology. For example, ring‐porous species tend to leaf out later than diffuse‐porous species, as their larger xylem vessels make them more vulnerable to frost damage (Marchin et al., 2015). It has also been suggested that more opportunistic pioneer species will adopt a more risky phenological strategies, relying solely on temperature cues, whereas late successional species will be more conservative, using the safeguards of large chilling requirement or high photoperiod sensitivity (Körner & Basler, 2010).…”

Time and heat for sexual reproduction: comparing the phenology of Chara hispida of two populations at different latitudes

“…As stated by Marchin et al (2015), predicting future responses of phenology to climate change in general, and warming in particular, requires a broad perspective and the use of a range of approaches. For instance, differences in temperature between two countries over the same year due to distinct geographical locations could be comparable, with caution, to the increment in temperature that the country located at the higher latitude would experience in the future under the warming scenario.…”

Changes in Climate, Forest Phenology, and Forest Disturbances Around Western Lake Superior

“…Forest vigor and growth interact both directly and indirectly with changes in climate [Pope et al, 2013;Marchin et al, 2015], complicating our ability to predict forest phenology, estimate carbon sequestration, and represent clearly the numerous land-atmosphere interactions within the climate system [Peñuelas et al, 2009;Richardson et al, 2013]. Proximity to large water bodies, such as Lake Superior, can affect local and regional temperature and precipitation patterns [Changnon and Jones, 1972;Scott and Huff, 1996;Hinkel and Nelson, 2012].…”

“…Meteorological and climatological factors have been shown to significantly influence vegetation seasonal phenology [Jolly et al, 2005;Koster et al, 2014;Xie et al, 2015] and explain a large fraction of observed year-to-year variability in temperate forest phenology [Fisher et al, 2007;Marchin et al, 2015], specifically as a primary factor in the annual growing season start, intensity, and duration. Changes may promote altered trajectories of forest health (e.g.…”