Species-specific combined
effects of heatwaves, drought, and elevated [CO2] on
cellular metabolism in the foliage Picea abies and Betula
papyrifera
Maegan A. Gagne1, Rakesh Minocha2,
Stephanie Long2, Katherine A.
McCulloh1
1Department of
Botany, University of Wisconsin-Madison, Madison, Wisconsin USA
2US Forest Service, Northern Research Station, Durham,
NH, USA
Correspondence to:magagne@wisc.edu, Forest
Service Northern Research Station 271 Mast Road Durham, NH 03824
Abstract
In recent decades, the rising severity of summer heatwaves has increased
the co-occurrence of heat and drought stress leading to forest mortality
and to reductions in crop yield. Plant responses to this combined stress
can be unique from the response to either independent stress, yet few
studies have investigated these responses in tree species. Our work
examines adjustment of several primary metabolites and polyamine (stress
indicating secondary metabolites) in paper birch and white spruce
subjected to two seasons of repeated heatwaves, drought, and
elevated CO2. Our
objectives were to determine if the metabolic adjustments in response to
heatwave+drought stress are: 1) unique or shared with either individual
stress; 2) greater in birch compared to spruce; and 3) carried over into
the following season. Our data show that white spruce displayed many
metabolic responses that were unique to the combined stress, especially
in the first year, while paper birch displayed few. Further, the unique
responses in spruce seen in the first season stress exposure did not
carry into the following season indicating possible stress memory. Our
data highlights the importance of considering species-specific responses
to multiple stressors when making predictions about forest response to
future climate scenarios.
Funding: This work was partially supported by the University of
Wisconsin-Madison and USDA Forest Service, NRS-16
Keywords: heat, drought, CO2, metabolome, amino
acids