Predicting Shifts in Nature's Lifecycles

October 19, 2020
Spring Cutting by Daniel Flynn

In nature, the timing of recurring annual lifecycle events affects many aspects of the ecosystem and ecology. In trees the timing of a leaf’s developing bud dictates the length of the growing season and carbon cycling, it mediates competition among plants and controls interactions with pests and pathogens.

The timing of spring buds developing in woody plants – trees, shrubs – is mainly controlled by environmental cues such as temperature and length of day. However, human driven climate change is causing spring events to occur earlier in the season. But how much these events continue to advance in the future is unknown.

In a paper published in Nature Climate Change a team of researchers addressed this question and the debate it’s generated and found that almost all species show strong responses to three environmental cues, with chilling – cool winter temperatures – being the strongest.

The team led by Ailene Ettinger, Putnam Fellow at the Arnold Arboretum, began their research five years earlier and included former OEB postdocs Ignacio Morales-Castilla, Dan Flynn and Tim Savas, and current PhD candidates Catherine Chamberlain and Daniel Buonaiuto (Holbrook Lab). The researchers analyzed 203 woody plant species from 73 globabally published papers.

Woody plants spring lifecycle is affected by temperature – chilling and forcing (warm spring temperatures – and length of day, or photoperiod – the amount of time exposed to light. Previous studies have shown though that species vary in the degree to which they rely on each cue, leading to a debate among researchers as to which cue is more important. This debate is crucial for projecting future spring lifecycles as relying on cues like chilling or photoperiod could slow the rate of shifts with global warming.

In the study, the team discovered that almost all species show strong responses to all three cues. The strongest response was chilling while photoperiod was the weakest. The study also resolved differing findings from previous studies and showed that, though most species respond to all cues in experimental conditions, forcing appears to determine responses to recent warming in nature.

The team applied their finding to predictions of shifts in the arrival of spring buds for Central Europe and found the timing of spring lifecycles is likely to continue to advance in the coming decades.

Elizabeth Wolkovich, former OEB professor and senior scientist on the study, and Ailene Ettinger have blogs covering the five-year study. 

Image courtesy of Daniel Flynn