unveilingtipping points in long-term and experimental ...tipping point the tipping point is the...
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Unveiling tipping points in long-term and experimental studies in peatlands
Mariusz LamentowiczKatarzyna Marcisz, Michał Słowiński, Vincent E.J. Jassey
Laboratory of Climate Change EcologyAdam Mickiewicz University, Poznań, Poland
Penard.de
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Tipping point
The tipping point is the corresponding critical point inforcing and a feature of the system at which the future stateof the system is qualitatively altered.
Lenton et al. 2008 PNAS
The tipping point in case of peatland ecosystems can bedefined as the critical point where they lose resilience andshift into a degraded state.
Questions
•What the tipping point (TP) means in case of peatland ecosystem?•Where was the hydrological baseline located in the last 2000 years? •When the baseline was lost?•How experimentally assessed TP relate to the palaeoecological inference?
Peat archive formation is a long-term process depending on water table
Fig. K. Tobolski
Fig. K. Tobolski
8000 years?!?
wow!
•Climate
•Drainage
•Mining
•Afforestation
Drivers of peatlands hydrological disturbances
Study sites
Lamentowicz i in. 2019. Biol Lett.
Mechacz
Kusowo
Last 2000 years in high-resolution
Proxies
• Testate amoebae-based water tablereconstruction,
• Plant remains –macrofossils
Sphagnum Sphagnum, Shrubs and sedges
Hyalosphenia papilio Assulina muscorum
Penard.de
Time scales
Lamentowicz i in. 2019 Biol Lett.
Tipping point in vegetation community composition
Baker, M., S. King, R., 2010. A new method for detecting and interpreting biodiversity and ecologicalcommunity thresholds. Methods in Ecology and Evolution. 1, 25–37.
Tipping point in vegetation community composition
14
Manipulation of the water table in a N Poland
Dry treatment
Ambient treatment
Wet treatment
Linje mire
We monitored ecosystem CO2 respiration and its potential drivers such as plant and fungal communities and enzyme activities.
From water level manipulation to water level gradient
Wat
er T
able
Dep
th (c
m)
-50
-40
-30
-20
-10
0
Date
13/01 13/03 13/05 13/07 13/09 13/11 14/01 14/03 14/05 14/07 14/09 14/11 15/01
WetAmbientDry
Fluctuations of water table depth spanned over gradient from -40 cm to -5 cmJassey et al. 2018. GCB
Jassey et al. 2018. GCB
Response of vegetation to water level gradient
Response of peatland functions to water level gradient
Water table depth (cm)
r2 = 0.28Threshold = -25.4 cm
-40 -35 -30 -25 -20 -15 -10 -50.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Soil
resp
iratio
n (µ
mol
CO2
m-2
min-1
)ü Important shifts in soil respiration and soil activity when the water level crossed -25 cm
Soil respiration
r2 = 0.47Threshold = -25.8 cm
-0.5
0.0
0.5
1.0
1.5
-40 -35 -30 -25 -20 -15 -10 -5
Enzy
me
activ
ities
(z s
core
s)
Water table depth (cm)
Enzyme activity
Jassey et al. 2018. GCB
Where is the tipping point located?
Ø 11,7 cm (2ky - palaeoecology)
Ø 20-25 cm (2-years experiment)
Fig. Kazimierz Tobolski
Plan
t cov
er (%
)
0
20
40
60
80
100WetAmbientDry
a
bb
bc
a aa
b a a a
bc
a
a
b
c
a
b
a
c a a
20
30
40
50
60
70
80
Water Table Depth (cm)
Tota
l vas
cula
r pla
nt c
over
(%)
12 months 15 months 18 months 27 months 12 months 15 months 18 months 27 months
-40 -35 -30 -25 -20 -15 -10 -5
R2 = 0.67Threshold = -20.5 cm
Carbon emission and water table
Jurasinski, 2015
Net GHG balance
GLOBAL WARMING POTENTIAL IS THE LOWEST ca 10 cm DWT!
• The inferred hydrological tipping point was WTD=12 cm for peat archives covering the last 2000 years (Lamentowicz et al. 2019),
• Experimental study provided value WTD=20-25 cm when substantial changes in ecosystem respiration, vegetation and soil fungal communities occurred in 2-years of manipulation (Jassey et al. 2018),
• Many of European peatlands crossed the long-term tipping point ca 200 years ago and lost resilience in response to drainage and climate change (Swindles et al. 2019).
• We conclude that the water table ca 12 cm indicates Sphagnum peatland resilience in the long-term ecological context and it is an important value in terms of greenhouse gasses balance and global warming potential.
Summary
