evolution of wetlands since the last glacial maximum
DESCRIPTION
Evolution of wetlands since the Last Glacial Maximum. Pirita Oksanen University of Bristol. Wetland synthesis - distribution, extent, type and accumulation Public database Maps Data – model comparisons Since ca. 21 000 BP Phase 1. Northern extratropics. Phase 2. Tropics. - PowerPoint PPT PresentationTRANSCRIPT
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Evolution of wetlands since the Last Glacial Maximum
Pirita Oksanen University of Bristol
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• Wetland synthesis - distribution, extent, type and accumulation
• Public database• Maps• Data – model comparisons• Since ca. 21 000 BP• Phase 1. Northern extratropics.• Phase 2. Tropics.
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• Peatlands net sink of CO2 – vegetation sequesters from the atmosphere
• Wetlands net source of CH4 – methanogenesis in waterlogged environment
• ca. 5 million km2 natural wetlands• over 1 million km2 irrigated cultivation • 400-500 Gt C in peat• 100-150 Tg CH4/a from natural wetlands• ca. 40 Tg CH4/a from rice paddies• estimates for the LGM 80-110 Tg CH4/a
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• temperature, water table and vegetation control CH4 production and flux
• wide variation of CH4 fluxes both between and within wetlands and seasons
Mean values (Aselmann & Crutzen -89)• Bogs – 15 (1-50) CH4/m2/day• Fens – 80 (28-216)• Swamps – 84 (57-112)• Marshes – 253 (137-399)• Floodplains – 100 (50-200)• Lakes – 43 (17-89)• Rice paddies – 310 (179-438)
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~INLAND WETLANDS~
BOGS
SWAMPS
FENS
OPEN WETLANDS
MARSHES
SPRINGS GEOTHERMAL WETLANDSFLUVIAL
LACUSTRINE
Open WoodedRaised Blanket
Aapa
Rich Oligotrophic
Eutrophic Mesotrophic
Wooded
Paludifying forestSwamp forest Cloud forest
Raised Rich
Open
Eutrophic Mesotrophic
Shrub-swamp
Shrub-marshCarr Alder thicket
Palsa mirePolygonal mire
Wet tundra
High palsa mire Plateau palsa mire
Sloping mire
Wet meadow
Saline/brackish AlkalineFreshwater
Flooded meadow Sedge marsh
Terrestrialising lake
~COASTAL/MARINE WETLANDS~
INTERTIDAL MARSHES INTERTIDAL SWAMPS
AQUATIC BEDSINTERTIDAL FLATS
Salt marsh Salt meadow SaltingRaised FreshwaterBrackish
Mangrove Nipah
Tidal freshwater swamp forest
~HUMAN-MADE WETLANDS~
AGRICULTURAL
ARTIFICIAL LAKES
CANALSEXCAVATIONS
Rice field Wet meadow
Pond Reservoir
Wastewater treatment
Thermokarst lake
Wet moor
Oligotrophic
Alpine wet meadow
~NOT WETLAND~DRIED PEATLAND BURIED PEATLAND
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Wetland vegetation plant functional types
OPEN
mosses with dwarf-shrubs and forbs – bogs and fens
tall sedges and grasses (>1.5 m height) - fens and marshes
low sedges and grasses - fens and other open wetlands
open water
WOODED (>5% tree cover) - bogs and fens
wooded, evergreen broad-leaved
wooded, evergreen needle-leaved
wooded, seasonal broad-leaved
wooded, seasonal needle-leaved
FORESTED (>40% tree cover) - swamps
forested, evergreen broad-leaved
forested, evergreen needle-leaved
forested, seasonal broad-leaved
forested, seasonal needle-leaved
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Mires today, sites with bottom dates
Previous databases used: Oksanen 2005, Gorham et al. 2005, McDonald et al. 2006, PAIN.
Lappalainen et al. 1996
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Basal peat dates 50 000 – 21 000 BP
Continental and ice-sheet outlines by Patrick Bartlein, University of Oregon
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Mires at 13000 BP
Experimental ice-sheet data by W.R Peltier, University of Toronto
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Mires
at 11000 BP
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Mires at 10000 BP
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Mires
at 9000 BP
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Mires at 6000 BP, sites with basal peat dates
Continental and ice-sheet outlines by Patrick Bartlein, University of Oregon
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Mire initiation in arctic/boreal regions
0
50
100
150
200
250
300
350
400
450
mire initiation casescumulative/ 5
0 2000 5000 8000 11000 15000 >21000