Will climate change cause disorder in phenology?

By Richard B. Primack  

 

“Can I not by expectation affect the revolutions of nature – make a day to bring forth something new?”  Henry David Thoreau in his Journal. 

 

There is concern that climate change will affect the phenology of plant and animal species in unpredictable ways, leading to ecological mismatches. This was examined in a recent paper in the journal Ecology using 10,000 time series of phenology from 1000 species across the Northern Hemisphere. 

 

Study sites are concentrated in Northern Hemisphere locations.

In examining this enormous set, the authors found that insect first occurrence, plant flowering, and leaf out times were more sensitive to temperature than bird arrival times. Early season species are more sensitive than later season species. This confirms the results of earlier studies.  

 

a. Hundreds of time series show that all four phenological events occur earlier with warmer temperatures, with bird arrival dates being the least sensitive. b. Phenological variability is not sensitive to temperature. Cross-hatched regions are not statistically significant.

 

There was no evidence for changing variability in response to warming temperatures. However, there was a significant trend for flowering and leafing out times to be less variable over time.   

 

The results suggest that while climate change is not fundamentally altering phenological variability, phenological patterns are changing. Perhaps this is due to changing species abundances or novel environmental constraints leading to non-linear responses.  

 

Stemkovski, M, JR Bell, ER Ellwood, BD Inouye, H Kobori, SD Lee, T Lloyd-Evans, RB Primack, B Templ, WD Pearse. 2022. Disorder or a new order: How climate change affects phenological variability. Ecology. DOI: 10.1002/ecy.3846