Avni Malhotra McGill University, Montreal avni.malhotra@mail.mcgill.ca

• Net Primary Production>>Decomposition

• 2-3% of total land surface; store 25-30% of the world’s soil carbon

• Carbon patterns and drivers related to internal feedbacks and external factors

Peatlands

bulk density

decomposition rate

hydraulic properties

peat & cohort depth

water table depth

mass remaining

plant/tissue type & NPP

nutrient status

cohort depth

peat depth

vegetation

peat

water

weather and climate

Feedbacks linking peat properties, accumulation, water, vegetation, climate

Frolking et al.(2010)

• Carbon patterns and drivers related to internal feedbacks and external factors

• Peatlands are considered to be self-regulated systems

• Important to understand self-regulation, given climate change scenarios

Peatlands

Anaerobic

Aerobic NEE (=GPP - R)

Photosynthesis (GPP) Respiration (R) Decomposition

Water table

Figure modified from Dr. Melanie Vile

Core of research proposal

Structure 1) Vegetation

2) Microtopography

3) Water table

Function 1) Net Ecosystem

Exchange

2) Decomposition Microtopography, Vegetation

Study Sites

Stordalen Mire, Sweden

Mer Bleue Bog, Canada

•Ombrotrophic bog without steep ecological gradients •More self-regulated and homogeneous

•Primary site •Steep ecological gradients •Variable degrees of self-regulation within site: permafrost, hydrology

Stordalen Mire

Palsa

Palsa South Fen

North Fen

Internal Lawn Palsa

Photo: J. Åkerman (Courtsey: David Olefeldt)

Palsa

• Point intercept method + Elevation data

• Stordalen and Mer Bleue (different spatial scales)

Preliminary Data: Relationship between Vegetation and Microtopography

Vegetation and Microtopography

Elevation of well (m)

350.4 350.6 350.8 351.0 351.2 351.4 351.6 351.8 352.0 352.2 352.4

Number of species present in quadrat

0

2

4

6

8

10

12

14

16

18

R2= 0.38 (p= 0.0003)

350.4 350.6 350.8 351.0 351.2 351.4 351.6 351.8 352.0 352.2 352.40

2

4

6

8

10

12

14

16

18

Fen

Palsa

Internal lawn

Elevation of well (m)

Number of species present in quadrat

Elevation data courtesy of Dr. Andreas Persson

Elevation and # of species: Significant relationship at Stordalen No longer significant!

Number of species

Elevation of well (m)

Elevation and # of species: No significant relationships at Mer Bleue (sub-site level)

Elevation data courtesy of Paul Wilson

Vegetation and Microtopography

Stordalen veg. overview (Site Level Scale)

Number of hits per species per quadrat 0

5

10

15

20

25

30

Litter

Lichens

Moss

Elevation (m)

350.4 350.8 351.2 351.6 352.0 352.4

0

10

20

30Dicranum elongatum

Polytrichum strictum

Sphagnum spp.

Sedges

0

50

100

150

200

250

Carex aquatilis

Carex rostrata

Eriophorum vaginatum

Shrubs

350.4 350.8 351.2 351.6 352.0 352.4-10

0

10

20

30

40

Andromeda polifolia

Betula nana

Empetrum negrum

Rubus chamaemorus

Vaccinium uliginosum

Vaccinium vitis-idaea

* R2= 0.18 p= 0.0378

* R2= 0.60 p= 0.0004 * R2= 0.27 p= 0.0032

Elevation data courtesy of Dr. Andreas Persson

Mer Bleue veg. overview: sample transect

(Sub-site Level Scale)

Bryophyte layer (percent cover)

Eriophorum vaginatum

Vaccinium myrtilloides

Ledum groenlandicum

Kalmia

angustifolia Oxycoccus

microcarpus

Chamaedaphne calyculata

Maianthemum trifolium

Elevation (m)

Quadrat number

R2= 0.46 (p=0.03)

R2= 0.54 (p=0.01)

Litter R2= 0.56 (p=0.01)

Litter S.magellanicum S.capillifolium P.strictum

Preliminary Data Conclusions

1. Number of species better correlated to elevation at Stordalen at site level than at sub-site level and not at MB sub-site level.

2. More individual species abundance correlated to elevation at MB compared to Stordalen- but at MB spatial autocorrelation included as scale level is lower.

Next steps: •Relationship with water

table •Veg. community level

questions •Relating to functional

processes

Wat

er t

able

dep

th (c

m)

Elevation (m)

R2= 0.86 (p<0.0001)

Preliminary Data Conclusions

Structure

1) Vegetation

2) Microtopography

3) Water table

Function

1) Net Ecosystem Exchange

2) Decomposition

Expect to find that in a more self-regulated system: 1) Stronger structure-function relationship 2) More up-scalability 3) Less steep gradients

Broad Research Objective: Understand self regulation in peatlands by observing the relationship between structure and function across areas of different self regulation.

Thank you!

Acknowledgements • Committee members for valuable feedback- Nigel Roulet, Tim Moore, Jill Bubier and Federic Guichard • Paul Wilson and Dr. Andreas Persson for elevation and WT data • Mike Dalva, Silvie Harder, Nadine Shatilla, Meaghan Murphy and Léa Braschi for help in the lab and field

Site Set-up: Sample S1-2Transect

Decomposition

Manual Water Table

NEE

Transition from Palsa to Internal fen