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Intensification effects on the energy, water and carbon balance of managed forests Denis Loustau, Sébastien Lafont, Jean-Pierre Lagouarde, Christophe Moisy,

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Presentation on theme: "Intensification effects on the energy, water and carbon balance of managed forests Denis Loustau, Sébastien Lafont, Jean-Pierre Lagouarde, Christophe Moisy,"— Presentation transcript:

1 Intensification effects on the energy, water and carbon balance of managed forests Denis Loustau, Sébastien Lafont, Jean-Pierre Lagouarde, Christophe Moisy, Delphine Picart, Alexandre Bosc (1) Virginie Moreaux (1,2) Fabienne Benest (3) (1)Inra, ISPA, Villenave d’Ornon, France (2)Global Change Research Group, San Diego State University, San Diego, Ca , USA, (3)Institut Géographique National, Bordeaux 33000, France EGU Annual Assembly 2014.

2 Climatic Impacts of Forest intensification (Lee et al., Nature 2011; Bright et al., GCB 2014; Luyssaert et al. Nature Climate Change, 2014 ) 1.GHG budget (CO 2, CH 4, N 2 O) 1.Net Atmospheric Exchange 2.Fossil fuel consumption (management) 3.Carbon stocks in situ: biomass, soil 4.Carbon stocks ex situ: harvested products, residues 5.Fossil fuel substitution : bioenergy, building, etc.. 2.Water balance 1.Evapotranspiration 2.Runoff, groundwater recharge 3.Energy balance 1.Surface radiative budget ( a, Ts) 2.Convective exchanges (r a, r s, LE, H)

3 Intensification of temperate Pine Forests

4 Forest model Climate scenario Approach: Comparison of homogenous forest landscapes converted from low (P60) to high (30) management intensity 1.Biogeochemical effect (carbon)  RF, GHG 2.Biophysical effect (albedo)  RF, albedo 3. Overall effect at 30 years (GWP) 1985 P30 P45 P60

5 1. Biogeochemical effects,  RF GHG (CO2)  In situ Carbon cycle modelled across x 90 ecoregions (GO+ INRA model)  Ex situ emissions & fossil C displacement Bioenergy: emissions same year, displace 0.7 fossil CO2 Timber: emissions delayed 60 yrs, displace 2.5 fossil CO2  Asymptotic decline of airborne fraction of CO 2  Overall radiative forcing according to Myhre et al. 98, Moreaux et al Soil Atmosphere Fossil C Harvest Vegetation Net CO 2 balance

6 Trees Soil Understorey Water cycle Energy balance Carbon cycle Plant develo pment Micro climate Climate forcing Management forcing  RF GHG (CO2) : Forest model GO+ (INRA) Groundwater

7 Soil (root depth) 40cm 80cm 120 cm - increases 2-3 fold the biomass production - more efficient in fertile site / favourable climates: intensification efficiency reduced in 2075 by drought Manag t  Results - Intensification impact on yield (90 ecoregions boxplots)

8 Soil (root depth) 40cm 80cm 120 cm Intensification may enhance soil carbon storage (litterfall ↗) In 2075, soil carbon is reduced at 70% of 2015 level. Manag t  Results- intensification impact on soil carbon stock

9 Soil (root depth) 40cm 80cm 120 cm Effect is stronger in fertile sites and humid climate Biomass carbon stock depleted by 30 % in intensified landscapes Manag t  Results- intensification impact on standing biomass

10  RF GHG (CO2) : Results synthesis in terms of radiative forcing  RF (W.m -2 ) P60  P  RF NEE  RF HP  Net  RF CO2 Cooling Warming In situ sequestration effect (NEE) is offset by mineralisation of harvested products (HP); The resulting net CO2 effect is due to storage in soil, biomass and products;

11  RF (W.m -2 ) P45  P P60  P30 Vertical axis range is 5 to - 10 E -5 W.m -2 Cooling impact from P60 to P30 Intensification effects decreases in the future Opposite trends evidenced for the P45  P30 conversion  RF GHG (CO2) : Results synthesis in terms of radiative forcing

12 Pine Forest, Bordeaux, SW France. 5km:  RF albedo Calibration from GEOLAND and MODIS products Reference Site: continuous cover including multiple ages Managed Site: ~even distribution of age classes [0 to 30] Comparison of monthly albedo time series at landscape level

13 SW France COPERNICUS ALBEDO product (AL-BH-BB) from VGT sensor. 1km / 10-day N - New Zealand Modis product MCD43A1 Collection 5 shortwave actual albedo 0.5 km / 8-day IntensiveReference unmanaged SW France N New-zealand  RF albedo : Results - Interannual mean of monthly values in albedo Albedo

14  RF (W.m -2 ) 3. Overall impacts of forest intensification P45  P P60  P30 Vertical axis range is - 10 E -5 W.m -2 CO2 Bioenergy Timber CO 2 Albedo

15  GWP 30 (W.m -2 ) 3. Overall impacts of forest conversion on GWP 30 P60  P30 CO 2 Albedo

16 Main points to take home. Intensification effects interact with climate and soil Albedo of intensively managed forests is 0.01 to 0.03 larger (not implying colder surface, Moreaux et al. 2011, Luyssaert et al. 2014) Changes in radiative forcing albedo and GHG have similar magnitudes – results are quite sensitive to fossil fuel displacement ratio; – Biogeochemical (CO2) impact > albedo’s under fertile conditions (climate & soil) Complete regional case studies are needed –Integration of fossil fuel cost of intensification –LCA of HP: biofuels, timber, biochar, biodiesel, electricity, heat.. –Radiative forcing adapted to local conditions e.g. using a 1D-column model

17 INRA ISPA SUPPORT Alexandre Bosc Sébastien Lafont Denis Loustau Christophe Moisy Virginie Moreaux* Delphine Picart Jean-Pierre Lagouarde IGN Fabienne Benest * (present address San Diego University) FORÊVER


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