TY  - JOUR
PY  - 2016//
TI  - A longer vernal window: the role of winter coldness and snowpack in driving spring transitions and lags
JO  - Global change biology
A1  - Contosta, Alexandra R.
A1  - Adolph, Alden
A1  - Burchsted, Denise
A1  - Burakowski, Elizabeth
A1  - Green, Mark
A1  - Guerra, David
A1  - Albert, Mary
A1  - Dibb, Jack
A1  - Martin, Mary
A1  - McDowell, William H.
A1  - Routhier, Michael
A1  - Wake, Cameron
A1  - Whitaker, Rachel
A1  - Wollheim, Wilfred
SP  - 1610
EP  - 1625
VL  - 23
IS  - 4
N2  - Climate change is altering the timing and duration of the vernal window, a period that marks the end of winter and the start of the growing season when rapid transitions in ecosystem energy, water, nutrient, and carbon dynamics take place. Research on this period typically captures only a portion of the ecosystem in transition and focuses largely on the dates by which the system wakes up. Previous work has not addressed lags between transitions that represent delays in energy, water, nutrient, and carbon flows. The objectives of this study were to establish the sequence of physical and biogeochemical transitions and lags during the vernal window period and to understand how climate change may alter them. We synthesized observations from a statewide sensor network in New Hampshire, USA, that concurrently monitored climate, snow, soils, and streams over a three-year period and supplemented these observations with climate reanalysis data, snow data assimilation model output, and satellite spectral data. We found that some of the transitions that occurred within the vernal window were sequential, with air temperatures warming prior to snow melt, which preceded forest canopy closure. Other transitions were simultaneous with one another and had zero-length lags, such as snowpack disappearance, rapid soil warming, and peak stream discharge. We modeled lags as a function of both winter coldness and snow depth, both of which are expected to decline with climate change. Warmer winters with less snow resulted in longer lags and a more protracted vernal window. This lengthening of individual lags and of the entire vernal window carries important consequences for the thermodynamics and biogeochemistry of ecosystems, both during the winter-to-spring transition and throughout the rest of the year.<br><br>© 2016 The Authors Global Change Biology Published by John Wiley & Sons Ltd.<p />  <p>Language: en</p>
LA  - en
SN  - 1354-1013
UR  - http://dx.doi.org/10.1111/gcb.13517
ID  - ref1
ER  -