Tundra Respiration in the
Land of the Midnight Sun
Nicholas Mirotchnick
University of Toronto
Owen Atkin
The Australian National University
Matthew Turnbull
University of Canterbury
Kevin Griffin
Columbia University
autotrophic respiration
NEP = GPP - R
net
ecosystem
productivity
gross
primary
production
respiration
measuring R
• confounded with photosynthesis in the light
• usually measured by darkening plants or
leaves (RD)
light inhibition of R
• R continues in the light (R ), but this is
L
usually ignored
• R is inhibited by light, but not completely
• carbon budgets need to account for this
the Arctic
respiration in light (RL)
• crucial in arctic ecosystems
• respiration is important to plants (e.g. for
growth) so they may be adapted to
constant daylight
the arctic is changing
• temperature
• cloud cover
• precipitation
• nutrient availability
• snowmelt
• species composition
the arctic is changing
• these changes affect R and R differently
• R has hardly been measured in the Arctic
L
L
D
• we don’t know:
• what arctic R is
• how this affects overall carbon budgets
• how this will change with climate
• but how to measure R ?
L
L
the Kok effect
traits
•
•
•
specific leaf area (SLA)
total non-structural carbohydrates (TNC):
•
•
•
•
fructose
glucose
sucrose
starch
photosynthetic capacity (Amax)
response variable
• inhibition of respiration by light:
• R /R
L
D
Toolik Lake, AK
Toolik Lake
LTER
blood, toil etc.
• 40 species
• 6-10 indvs./sp.
Aconitum
delphinifolium
Anemone parviflora
Arctostaphylos
alpina
Artemisia alaskana
Astragalus
umbellatus
Calamagrostis
canadensis
Carex aquatilis
Carex bigelowii
Carex saxatilis
Dryas integrifolia
Dryas Octopetala
Elymus trachycaulus
Epilobium latifolium
Equisetum arvense
Eriophorum
angustifolium
Eriophorum
vaginatum
Festuca rubra
Gentiana glauca
Geum glaciale
Hedysarum alpinum
Kobresia
myosuroides
Kobresia Sibirica
Ledum palustre
Oxytropis deflexa
Oxytropis
maydelliana
Oxytropis nigrescens
Petasites frigidus
Polygonum bistorta
Potentilla fruticosa
Potentilla nivea
Potentilla palustris
Rhododendron
lapponicum
Salix glauca
Salix pulchra
Salix reticulata
Saussurea
angustifolia
Spiraea
beauverdiana
Vaccinium
uliginosum
Vaccinium vitisidaea
inhibition
inhibition
inhibition by species
inhibition by functional group
inhibition by functional group
functional traits
model
p
AIC
R2
Amax/sucrose
0.002 -8.73 0.26
Amax/fructose/sucrose
0.004 -7.64 0.25
Amax/fructose/glucose/SLA/sucrose 0.02 -4.62 0.23
inhibition by family
inhibition by family
conclusions
• arctic R is 76% of R
• inhibition does not depend on species or
L
D
functional groups
• inhibition depends on sucrose, A
max
implications
• there is less carbon in the arctic than we
think
• compositional shifts could alter carbon
stocks over time
• functional groups are less informative than
traits
Acknowledgments
Columbia:
U of T:
Heather Greaves
Jonathan Billig
Mary Heskel
Dan Flynn
Maria Uriarte
Shahid Naeem
Marc Cadotte
Caroline Tucker
Bill Cole
Spencer Barrett
Rowan Sage &
lab
Toolik Lake
staff and
researchers
NSF