Réduction de la biomasse en forêt boréale de l’Est du Canada sous l’effet

des changements climatiques

Emeline ChastePhD in Environmental ScienceUniversity of Quebec in Montreal (Canada)École Pratique des Hautes Études(France)

Supervision :Martin Girardin, Christelle Hély, Yves Bergeron

Collaboration: Jed Kaplan

emeline.chaste@agroparistech.fr

Jour

née

Mod

èle

Qué

bec

Jeud

1 1e

r no

vem

bre

2018

11

Intr

oduc

tion

5

Objectives

3

The tool used:

� Evaluate how climate, atmospheric [CO2] and wildfires mayaffect the biomass of dominant tree species in Canada’s managedboreal forest in the coming decades;

� Assess the spatial heterogeneity in climate change impacts, notablyalong temperature (e.g. north to south) and precipitation (e.g. west toeast) gradients.

Picea Abies Pinus Populus

Reparameterized for 4 PFTs:

CLIMATE

VEGETATION FIRE

(Chaste et al. 2018)

Mét

hodo

logi

e

6

LPJ-LMfire model

4

WeathergeneratorIn

puts

Out

puts

Environmental

constraints

Climate

Fire % cover

Biomass NPP

ECOSYSTEM

Daily processes

Annual processes

Reproduction

Establishment

Mortality

Fire

Leafs-roots-wood

turnover

Biomassallocation &

growthStomatalregulation

Photosynthesis

Plant respiration

Leafs-rootsphenology

Decomposition

Soilhydrology

Mét

hodo

logi

e

8

Input datasets(1950 - 2099)

5

1 2

3 4

5

6

7

Climate : Maps of monthly mean for 7 variables

Environmental constraints: Maps of…

4 variables 3D

1

2

3

4

10 km x 10 km

Mét

hodo

logi

e

8

Input datasets(1950 - 2099)

5

1 2

3 4

5

6

7

Climate : Maps of monthly mean for 7 variables A multi-model ensemble of 6 climate scenarios

(6CS) that combines:

RCP: 4.5 8.5

GCM:

EARTH

GCM:CanESM2

EC-EARTH

RCM: RCA4

CanRCM4+ +

10 km x 10 km

H0

1

LPJ-LMfire: Annual burn rates (%)R

ésul

tats

6-60% -

75%

-33%

-24% -

35%

+2% (-8;+12)

Changes in the 2071-2099 period relative to 1951-1980

+

-

Reduction of fire activity

In summary:

1

LPJ-LMfire: Biomass (T.ha-1)

7-33%

-55%

+7%

-7% -13%

+7%

+

-

Decrease in biomass

In summary:

Changes in the 2071-2099 period relative to 1951-1980

Rés

ulta

ts

(1) forest cover loss(2)(3)

1

LPJ-LMfire: Tree cover (%)

8

-33%

-55%

-7%-

13%

Decrease inbiomass

associated with…

coniferous speciesPopulus (1) forest cover gain

(2)(3)

Increase inbiomass

associated with…

coniferous speciesPopulus

+7%+7%

Cumulative tree cover (%) are not correct (see Chaste et al. 2018), but:

Rés

ulta

ts

1

LPJ-LMfire: Growth (NPP; T.ha

9+11%

-27%

+86%

+25%+19%

+44%

In summary:

-

+

Increase in NPP

Changes in the 2071-2099 period relative to 1951-1980

Rés

ulta

ts

1

LPJ-LMfire: results coherence?Decrease in firesDecrease in fires Increase in NPPIncrease in NPP

Decrease in biomassDecrease in biomass

Detailed analyses

10

Rés

ulta

ts

1

LPJ-LMfire: Detailed analyses

Second half of the 21st century:establishment rates

that do not compensate forheat-induced mortality rates

+ -

West East

11

Rés

ulta

ts

1

LPJ-LMfire: Detailed analyses Who's acting on the forest cover loss?

12

Rés

ulta

ts

Con

clus

ion

1

To keep in mind : Impacts of climate change will be very significant throughout Canada’smanaged boreal forest by the end of the 21st century, but they will be subjectto major differences across the region:

13

Climate changeClimate change

FireFire

Forest

Tree cover(%)

Biomass(T.ha-1)

Composition

NPPNPP

+

-

+

+

Heat-inducedtree mortality

rates

Heat-inducedtree mortality

rates

-

-

+

SouthNorth and South /

(1) Vegetation "bottom-up" control;

(2) Stimulating effects of increasingtemperatures and atmospheric[CO2] on boreal forest productivity;

(3) heat-induced mortalityevents

forest cover loss

negative feedback on fires

The enhancement ofvegetation growth by climatechange would not beunlimited and may becounteracted by the negativeeffects of climate change onfires and other plantprocesses, such as tree

1

Many thanks to:� Martin Girardin, Christelle Hély and Yves Bergeron

� Professor Jed Kaplan from the University of Lausanne

� Xiao Jing Guo , biostatistician at the Laurentianforestry center

� Daniel Stubbs, scientific analyst at Calcul Quebec

� Travis Logan, specialist at Ouranos Consortium

� Our partners:

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1

Questions?

15