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How often and under what circumstances does wetland drying or thawing of permafrost cause a change in ecosystem state?
How often and under what circumstances does wetland drying or thawing of permafrost cause a change in ecosystem state?
Crossing the final ecological threshold in high Arctic ponds
Smol and Douglas 2007PNASSmol and Douglas 2007PNAS
Barber et al. 2004Climatic ChangeBarber et al. 2004Climatic Change
Klein et al.Can. J. For. Res. 2005Klein et al.Can. J. For. Res. 2005
Burn, C. R. 2005 Permafrost and Periglac. Process. Burn, C. R. 2005 Permafrost and Periglac. Process.
Yoshikawa and Hinzman 2003 Permafrost and Periglac. Process. Yoshikawa and Hinzman 2003 Permafrost and Periglac. Process.
Smith et al. 2005 Science “Disappearing Arctic Lakes”Smith et al. 2005 Science “Disappearing Arctic Lakes”
Riordan et al. JGR 2006
Yoshikawa et al.2002JGRYoshikawa et al.2002JGR
15-June-1986 Image
16-June-2001 Image
1988 Burn
1988 Burn
25-June-2001
28-June-2005
Consequences of a changing hydroclimate for organic-rich
wetlands
CZEN
Plant fixation and allocation
Peat accumulation
Climate
Microbial metabolism
www.apex.msu.edu
APEX Gradient sites
Rich fen
Black Spruce
Willow/Bog Birch
Tussock Grass
Emergent
LoweredControl Raised
www.apex.msu.edu
-35
-30
-25
-20
-15
-10
-5
0
5
10
201
206
212
217
222
228
233
238
243
249
254
259
265
270
275
280
286
Julian Day 2005
Wat
er t
able
dep
th (
cm)
Control LoweredRaised
Pumping initiated for raised treatment
-35
-30
-25
-20
-15
-10
-5
0
5
10
201
206
212
217
222
228
233
238
243
249
254
259
265
270
275
280
286
Julian Day 2005
Wat
er t
able
dep
th (
cm)
Control LoweredRaised
Pumping initiated for raised treatment
www.apex.msu.edu
www.apex.msu.edu
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
NEE
CO
2 (µm
ol m
-2 s
-1)
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
NEE
CO
2 (µm
ol m
-2 s
-1)
CONTROL RAISED LOWERED
Net Ecosystem Exchange
Ecosystem Respiration
Gross Primary Production
a ab
e
d
f
c
abc
d
a ababc
bc
ac
e
a
d
b
2005
2006
www.apex.msu.edu
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
CONTROL RAISED LOWERED
Net Ecosystem Exchange
Ecosystem Respiration
Gross Primary Production
a ab
e
d
f
c
abc
d
a ababc
bc
ac
e
ad
b
2005
2006
www.apex.msu.edu
0
1
2
3
4
5
ER C
O2 (
µmol
m-2
s-1
)
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
GPP
CO
2 (µm
ol C
O2 m
-2 s
-1)
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
CONTROL RAISED LOWERED
Net Ecosystem Exchange
Ecosystem Respiration
Gross Primary Production
a ab
e
d
f
c
abc
d
a ababc
bc
ac
e
ad
b
2005
2006
www.apex.msu.edu
0 500 1000 1500 2000 15
10
5
0
-5
-10
NEE (
mol m
-2 s
-1)
PAR (mol m-2 s-1)
Raised
Control
Lowered
Light response curves
• ET & plant responses to water table treatments
0
0.5
1.0
1.5
2.0
2.5
3.0
-12-10-8-6-4-20
controllowered
raised y = -0.18x - 0.098; R2=0.50
Evap
otr
an
sp
irati
on
(mm
/h
r)
Gross Primary Productivity (µmol CO2 m2/ s)
0
0.5
1.0
1.5
2.0
2.5
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
-12-10-8-6-4-20
controllowered
raised y = -0.18x - 0.098; R2=0.50
Evap
otr
an
sp
irati
on
(mm
/h
r)
Gross Primary Productivity (µmol CO2 m2/ s)
www.apex.msu.edu
mol C
H4 m
-2 m
in-1
012345678
Control Lowered Raised
c cdd
e
a
b
warming
Coupled carbon – water dynamics• CH4 flux sensitive to soil hydroclimate (Treat et al. in review)
Mean daily WT position (cm)
CH
4 fl
ux (
mg
m-2 d
-1)
-70 -60 -50 -40 -30 -20 -10 0 10
0
100
200
300
400ControlLowered
Raised
no warming
0 50 100 150 200 250100
150
200
300
350
400
450
250
An
nu
al org
an
ic m
att
er
sto
rag
e
(g o
rgan
ic m
att
er
m-2 y
r-1)
Time since permafrost degradation
Turetsky et al. 2006
-0.2-0.2
0.00.0
0.20.2
0.40.4
0.60.6
0.80.8
1.01.0
3/203/20 4/94/9 4/294/29 5/195/19 6/86/8 6/286/28 7/187/18 8/78/7 8/278/27 9/169/16 10/610/6
Permafrost Plateau
Thermokarst Edges
ThermokarstWetlands
mm
ol C
Hm
mo
l CH
44 m m
-2-2 h
r h
r-1-1
Methane Fluxes, 2003Methane Fluxes, 2003
*Each point is the mean *Each point is the mean ± one standard deviation of one to five measurements. ± one standard deviation of one to five measurements. Measurements on 3/25 were made in 2004.Measurements on 3/25 were made in 2004. Wickland et al., 2006
Flashier!
0.0
0.10.2
0.3
0.4
0.5
0.60.7
0.8
0.91.0
- 40- 35- 30- 25- 20- 15- 10- 50
0.0
0.10.2
0.3
0.4
0.5
0.7
0.8
0.91.0
0.0
0.10.2
0.3
0.4
0.5
0.7
0.8
0.91.0
- 40- 35- 30- 25- 20- 15- 10- 50
0.0
0.10.2
0.3
0.4
0.5
0.7
0.8
0.9
- 40- 35- 30- 25- 20- 15- 10- 50 - 40- 35- 30- 25- 20- 15- 10- 50
Sto
rag
e C
oeffi
cie
nt
Water table position (cm)
Pristine
Brown moss rich fen, AK
Sphagnum poor fen, QB
Drained
Wetland ecohydrology can be surprising
• Vegetation -> peat properties -> hydrology
