Réduction de la biomasse en forêt boréale de l Est du Canada sous l effet des changements climatiques

Transcription

1 Journée Modèle Québec Jeud er novembre 208 Réduction de la biomasse en forêt boréale de l Est du Canada sous l effet des changements climatiques Emeline Chaste PhD in Environmental Science University 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

2 Introduction Objectives Evaluate how climate, atmospheric [CO 2 ] and wildfires may affect the biomass of dominant tree species in Canada s managed boreal forest in the coming decades; Assess the spatial heterogeneity in climate change impacts, notably along temperature (e.g. north to south) and precipitation (e.g. west to east) gradients. The tool used: CLIMATE VEGETATION FIRE 53 Reparameterize d for 4 PFTs: (Chaste et al. 208) Picea Abies Pinus Populus

3 Méthodologie 6 LPJLMfire model 4 Weather generator Inputs Outputs Environment al constraints Climate Fire % cover Biomass NPP E C O S Y S T E M Daily processes Annual processes Reproducti on Establishm ent Mortality Fire Leafsrootswood turnover Biomass allocation & growth Stomatal regulation Photosynthe sis Plant respiration Leafsroots phenology Decompositi on Soil hydrology

4 Méthodologie Input datasets ( ) Climate : Maps of monthly mean for 7 variables 2 5 Environmental constraints: Maps of 4 variables 3D 0 km x 0 km

5 Méthodologie Input datasets ( ) Climate : Maps of monthly mean for 7 variables A multimodel ensemble of 6 climate scenarios (6CS) that combines: RCP: GCM: CanESM2 EC EARTH 0 km x 0 km RCM: RCA4 CanRCM4 85 H 0

6 Résultats LPJLMfire: Annual burn rates In summary: 6 Reduction of fire activity 33% 2% (8;2) 24% 35% 60% 75% Changes in the period relative to 95980

7 Résultats LPJLMfire: Biomass (T.ha ) In summary: 7% 7% 7 Decrease in biomass 33% 55% 7% 3% Changes in the period relative to 95980

8 Résultats LPJLMfire: Tree cover (%) Decrease in Increase in biomass biomass 7% 7% 33% 7% 55% 3% associated with associated with 8 () forest cover loss (2) coniferous species (3) Populus Cumulative tree cover (%) are not correct (see Chaste et al. 208), but: () forest cover gain (2) coniferous species (3) Populus

9 Résultats LPJLMfire: Growth (NPP; T.ha In summary: 9 Increase in NPP 86% % 25% 27% 44% 9% Changes in the period relative to 95980

10 Résultats LPJLMfire: results coherence? Decrease in fires Decrease in biomass Increase in NPP 0 Detailed analyses

11 Résultats LPJLMfire: Detailed analyses Second half of the 2 st century: establishment rates that do not compensate for heatinduced mortality rates West East

12 Résultats LPJLMfire: Detailed analyses Who's acting on the forest cover loss? 2

13 Conclusion To keep in mind : Impacts of climate change will be very significant throughout Canada s managed boreal forest by the end of the 2st century, but they will be subject to major differences across the region: Climate change () Vegetation "bottomup" control; (2) Stimulating effects of increasing temperatures and atmospheric [CO 2 ] on boreal forest productivity; Heatinduced tree mortality rates Fire NPP (3) heatinduced mortality events forest cover loss 3 Forest Tree cover (%) Biomass (T.ha ) Composition North and South South / negative feedback on fires The enhancement of vegetation growth by climate change would not be unlimited and may be counteracted by the negative effects of climate change on fires and other plant processes, such as tree

14 Many thanks to: Martin Girardin, Christelle Hély and Yves Bergeron Professor Jed Kaplan from the University of Lausanne Xiao Jing Guo, biostatistician at the Laurentian forestry center Daniel Stubbs, scientific analyst at Calcul Quebec Travis Logan, specialist at Ouranos Consortium Our partners: 4

15 Questions? 5