AN ECOLOGICAL–ECONOMIC ANALYSIS OF CLIMATE MITIGATION THROUGH REWETTING PREVIOUSLY
DRAINED HEMIBOREAL PEATLANDS
Åsa Kasimir, Jessica Coria, Hongxing He, Xiangping Liu, Anna Nordén and Magnus Svensson
Department of Earth [email protected]
Biodiversity and Ecosystem services in a Changing Climate
11 Tg CO2e yr-1 18 Tg CO2e yr-1
≈
≈
Wetlands store carbon and plant nutrients
But release some methane
CN
N2O ≈ zero
CH4
CO2
Peat
When drained; carbon dioxide and nitrous oxide emissions
• Aerated soil makes agriculture and forestry possible.
• Decomposition of peat, the source for CO2 and N2O emission.
• Continues as long as the soil is drained or all peat has disappeared.
C
N
Ditch CO2 N2O
• Soils contain three times more C than living biomass.• Peatlands contain nearly 30% of the world’s soil carbon
covering 3% of the earth’s land area.• Land use contribute 24% of anthropogenic GHG
emissions
Skogaryd• Spruce forest on drained soil earlier used for agriculture• >1 m deep fertile peat • A lot of measurement data
Climate data - drives the modell• Precipitation• Air temperature• Relative humidity• Global radiation• Wind speed
Calibration; data 2007-2009• Net solar radiation• NEE• Soil emission N2O and CO2 • Soil temperature• Soil water• GWL• Soil energy flow
Skogaryd, drained peat soil CoupModell
Water and energy flow
Plant module
C and N flow module
P.-E. Jansson & D.S. Moon 2001.P.-E. Jansson 2012.
Hongxing He et al. 2016. Factors controlling Nitrous Oxide emission from a spruce forest ecosystem on drained organic soil, derived using the CoupModel. Ecological Modelling
Simulated total GHG balance for the forest ecosystem from 1951 to 2011 and extended to 2031. Note that the GHG balance presented assumes no final harvest.
Before harvest: the total net G
HG
loss over 80 years, 1 Gg CO 2eq ha-1
Hongxing He et al. (2016) Forests on drained agricultural peatland are potentially large sources of greenhouse gases – insights from a full rotation period simulation. Biogeosciences 13, 2305–231
Four scenarios modelled by Coup
aim; to assess emissions and economy
•80 year rotation
1. Spruce, GWL ~40 cm depth (business as usual scenario),
2. Salix, GWL ~20 cm depth,
3. Reed Canary Grass, GWL ~10 cm depth,
4. Rewetting, GWL in the soil surface (~0 cm)
Vegetation Norway spruce Willow RCG Wetland
Average GWL set cm -40 -20 -10 0
Average GWL obtained -48 -22 -13 0
Biomass growthm3 ha-1 yr-1
Mg CO2 ha-1 yr-1
15.911.0
13.610.0
26.69.7
1.31
Emissions: Mg CO2eq ha-1 yr-1
CO2 emission 20.1 13.1 6.4 1
N2O emission 3.0 2.4 <0.01 0
CH4 emission (0.2) (0.2) (0.2) 2.6
Leaching:
Leaching of nitrate kg N ha-1 yr-1 32 6.9 5.1 0
Leaching of DON kg N ha-1 yr-1 8.7 4.5 3.7 0
Leaching N into N2O Mg CO2eq ha-1 yr-1 0.3 0.1 0.1
Leaching of DOC Mg CO2 ha-1 yr-1 0.11 0.04 0.01 ~0
Mineralized DOC in lakes2 Mg CO2 ha-1 yr-1 0.2 0.1 0.02
Total GHG emissions3 Mg CO2eq ha-1 yr-1 24 16 6.7 1.3
CoupModel simulation results.
GHG mitigation by rewetting and vegetation change
Year
1950 1970 1990 2010 2030
Mg C
O2 ha
-1
-2000
-1500
-1000
-500
0
Spruce -40 cm groundwater levelWillow -20 cm groundwater level Reed Caney Grass - 10 cm groundwater levelRewetting to 0 cm groundwater level
by-33%
by-72%
by-89%fro
m s
pruc
e to
will
ow
from
spr
uce
to R
CG
from
spr
uce
to re
wet
Modelled accumulated soil carbon loss
12
Economics
Products sold on the market minus management cost 3384 1847 1697 0
Concrete /steel replacement Replacement of fossil fuels
1250530
01031
0704
00
Ecosystem Services - Biodiversity 0 0 0 1517
CO2 emission -4371 -3248 -1814 96
CH4 emission -46 -46 -46 -463
N2O emission -741 -660 -1 0
N2O due to nitrate leaching -39 -8 -5 0
CO2 from DOC leaching to water -89 -33 -5 0
Cost of management of ditches/ restoring wetland -14 -14 -14 -404
Net Annuity Value (SEK ha-1 year-1) -136 -1131 516 746
Benefits (SEK ha-1 year-1) (+)
Costs (SEK ha-1 year-1) (-)Marginal damage costs, Social Cost of Carbon SCC= 175.2 SEK ton-1 CO2eq
GWL, cm
0 10 20 30 40 50 60
Biom
ass growth or G
HG
soil emission, M
g CO
2eq ha-1
yr-1
0
5
10
15
20
25
30
35
Spruce growthWillow growthRCG growthSpruce soil GHGWillow soil GHGRCG soil GHG
GWL Sensitivity of Biomass and GHG emission for scenario 1, 2 and 3
Emission factors, IPCC default and estimated in this project
IPC
C E
F
IPC
C E
F
IPCC EF are for drained wetlands in Temperate climate
Where to find forest on drained peat:
Ernfors et al. 2007
In Sweden; 500 kha forest on fertile drained peat with a peat depth larger than 30 cm, like in Skogaryd.
Based on our modeled GHG emissions these areas emit 12 Tg CO2eq every year, possible to reduce by 33%, 72% or 89%.
Wetlands; 1/5 of Sweden area
11 Tg CO2e yr-1 18 Tg CO2e yr-1
≈
≈
1.2 Mha forest and 200 kha agriculture