New publication: The phenomena of transitional mortality

Using the lovely study system of yellow-cedar, a new paper explores climate-induced mortality of a different sort than the usual threshold type mortality.  Once I started looking at the whole range, it became apparent that it wasn't so much the climate was too warm for yellow-cedar, but rather the transition from cold-to-warm was detrimental.  In fact, very healthy populations are in quite warm environments.  This led to the conclusion, supported by weather station data spanning about 10 degrees of latitude, that mortality is indeed associated with the transition rather than a threshold per se.  

Capture.JPG

 

The fascinating result is that in this case, slower warming (longer time in the transition) may lead to increased mortality.  It can be captured with a simple binomial model, where the odds for a mortality event are commensurate with the time of exposure climatically and the probability of a thaw-freeze event during that time.  This structure matches the observed data pretty well, though limited data in southeast Alaska (primarily due to a lack of weather stations, and non-random location of those stations) means we're still generally in the hypothesis stage and can't make really concrete conclusions yet - need to move into better instrumented areas and retest (it's science - always retest!).  But it's compelling, and this could be a useful concept in other places.

 Predicted mortality from the simple binomial model which combines years of exposure and the probability of a thaw-freeze event over that time.

Predicted mortality from the simple binomial model which combines years of exposure and the probability of a thaw-freeze event over that time.

The manuscript will be coming out in Ecosphere:  

Buma B.  Transitional climate mortality:  Slower warming may result in increased climate-induced mortality in some systems.  Ecosphere.  In press.