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Harvesting slash residues in forests: a sustainable opportunity for the bioenergy sector?
Laurent Saint-André, D. Achat, Nicolas Bilot, Laurent Augusto, Arnaud Legout, Holger Wernsdorfer, Jean-Paul Laclau, Christine Deleuze, Jacques
Ranger
To cite this version:
Laurent Saint-André, D. Achat, Nicolas Bilot, Laurent Augusto, Arnaud Legout, et al.. Harvesting slash residues in forests: a sustainable opportunity for the bioenergy sector?. Session on Biomass for Energy, Jun 2015, Pékin, China. pp.19 slides. �hal-02793989�
Harvesting slash residues in
forests: a sustainable opportunity
for the bioenergy sector?
Saint-André L, Achat D., Bilot N., Augusto L.,
Legout A., Wernsdörfer H., Laclau J-P., Deleuze C., Ranger J.
Context and main issues
Energy policies
Current energy policies are characterized by two complimentary
objectives:
Ø
to reduce fossil energy consumption
Ø
to develop renewable energies market, particularly woodfuel sector
European energy policies target a proportion of 20% renewable energies in total energy consumption of whole EU for 2020 (2009/28/CE) - France: 23%
Increase forest
management
intensity
Sto very short rotation cropping systems dedicated to wood
production (see Marron et al. this session)
Increased harvesting in existing forest ecosystems (this presentation)
Impact on soil
and forest
Context and main issues
Scientific challenges
Soil fertility in forest ecosystems ?
Total reserves = long term
Soil organic matter
Soil mineral
Weathering = current restoration Mineralization = current restoration
Exch. + available reserves = current
Uptake from the trees Restitution by litter falls
and root turn-over
Soil chemical fertility is based on a small
amount of nutrient circulating rapidly in
the ecosystem
BIOCHEMICAL Sub-Cycle - translocations BIOLOGICAL Sub-Cycle - Canopy Exchanges - Nutrient uptake - Immobilization - Litter falls- Mineralization of organic matters
GEOCHEMICAL Sub-Cycle - Atmospheric deposits - Weathering - Drainage - Run-off The partitionning between these sub-cycles is ecosystem-dependant Hanson et al. 2015
Context and main issues
Scientific challenges
Harvesting slash residues = modification of the biological cycle
Organic matter mineralisation (C, N, Cations)
Contribute to the maintenance of soil chemical
properties and soil biodiversity (macro-, meso-, micro- fauna) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Biomass (t/ha) N (kg/ha) Feuilles
Branche totale Tronc Total
Beech, 80 years, Fougères, France
192 65 3 74 205 275 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Biomass (t/ha) N (kg/ha) Leaves Branches Stembark Stemw ood 2 6.5 5 80 113 20 22.5 56
Eucalyptus, 6 years, Pointe-Noire, Congo
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Biomass (t/ha) N (kg/ha) Needles
Branches Stembark Stemw ood
Douglas fir, 60 years, Vauxrenard, France
352 45 50 16 195 154 121 225
A concrete example, the CIFOR
network
Definitive
Designation SouthAfrica Congo Brazil China India Australia
SMT0 BL0 BL0 BL0 BL0 BL0 BL0 Stemwood Bark Crown
SMT1 BL2 BL2 BL2 L BL2
SMT2 BL2 BL4 BL1
SMT3 BL3 BL3 BL3 BL3 BL3 Removed
SMT4 BS BL5 SLb BS B Removed Removed* Removed Removed**
* Removed in Congo, China and India ** Removed in India
Commercial trees Non Commercial Trees +
Designation in the published studies
Left
Removed Left
Left + Slash added Burnt
Litter on the soil + Understorey
Removed
Slash Management at harvesting
Assessing the Impact of Slash Management on the Eucalyptus
Productivity
Ø
6 countries, 10 sites
Ø
Eucalyptus plantations
Ø
Same treatments applied in each country (bare soil to double slash)
Ø
Unique modelling framework to assess the impact of slash
management on the site index (SI), the ability of trees to produce
biomass at a given SI, the between tree competition and the
A concrete example, the CIFOR
network
Assessing the Impact of Slash Management on the Eucalyptus
Productivity
Dominant height as a function of ageSite Index
Congo 0 5 10 15 20 25 30 35 0 12 24 36 48 60 72 84 96 Age (Months) D o m in an t H ei g h t (m ) SMT0 SMT1 SMT2 SMT3 SMT4 4C) Australia - Busselton 0 5 10 15 20 25 30 35 0 24 48 72 96 120 144 Age (Months) D o m in an t H ei g h t (m ) SMT0 SMT1 SMT3 SMT4 4C) Brazil 0 5 10 15 20 25 30 35 0 12 24 36 48 60 72 84 96 108 Age (Months) D o m in an t H ei g h t (m ) SMT0 SMT1 SMT2 SMT4 4B) South-Africa 0 5 10 15 20 25 30 35 0 12 24 36 48 60 Age (Months) D o m in an t H ei g h t (m ) SMT0 SMT2 SMT3 SMT4 4B) China 0 5 10 15 20 25 30 35 0 12 24 36 48 60 72 84 96 108 Age (Months) D o m in an t H ei g h t (m ) SMT0 SMT1 SMT3 4A) India-Vattavada 0 5 10 15 20 25 30 35 0 12 24 36 48 60 72 84 Age (Months) D o m in an t H ei g h t (m ) SMT0 SMT1 SMT3 SMT4 4A)- Unchanged - Temporary changed - Changed
A concrete example, the CIFOR
network
Assessing the Impact of Slash Management on the Eucalyptus
Productivity
Stand Basal Area Growth as function of dominant
height growth Capacity of trees to produce biomass at a given
Site Index Congo 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 Dominant Height grow th Increment
(m/month) B as al A re a g ro w th in cr em en t (m 2/ m o n th ) SMT0 SMT1 SMT2 SMT3 SMT4 5c) South-Africa 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 Dominant Height grow th Increment
(m/month) B as al A re a g ro w th in cr em en t (m 2/ m o n th ) SMT0 SMT2 SMT3 SMT4 5b) Brazil 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 Dominant Height grow th Increment
(m/month) B as al A re a g ro w th in cr em en t (m 2/ m o n th ) SMT0 SMT1 SMT2 SMT4 5a) China 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 Dominant Height grow th Increment
(m/month) B as al A re a g ro w th in cr em en t (m 2/ m o n th ) SMT0 SMT1 SMT3 5a) India - Kayampoovam 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 Dominant Height grow th Increment
(m/month) B as al A re a g ro w th in cr em en t (m 2/ m o n th ) SMT0 SMT1 SMT3 SMT4 5b)
- Unchanged - Changed but non significantly - Significantly Changed
A concrete example, the CIFOR
network
Assessing the Impact of Slash Management on the Eucalyptus
Productivity
Saint-André et al. 2008 y = 0.262Ln(x) - 1.1815 R2 = 0.7419 -30% -20% -10% 0% 10% 20% 30% 40% 50% 60% 70% 80% 0 200 400 600 800 1000Ratio N dans les residues / N dans le sol
In te n si té d e la r ép o n se s u r la s u rf ac e te rr iè re
As a result the impact reached up
to 30% for height growth, 20%
for the circumference and 70%
for the stand basal area after one
rotation
Site Fertilization (kg/ha) Residues (kg/ha) Total (kg/ha) C (g/kg) N (g/kg) C/N Height Circ G Ratio N/soilN
Congo 16 349 365 5.4 0.34 16 30% 19% 73% 1073.5 Brazil 15 296 311 16.6 0.96 17 20% 19% 41% 324.0 South-Africa 17 1378 1395 66.5 3.2 21 16% 13% 35% 435.9 India-Kayampoovam 42 100 142 21.5 1.83 12 7% 3% 22% 77.6 China 17 134 151 8.33 0.7 12 11% 13% 18% 215.7 India-Vattavada 42 150 192 52.3 4.5 12 11% 13% 14% 42.7 India-Surianelli 42 90 132 40.9 2.49 16 10% 6% 20% 53.0 India-Punnala 42 50 92 43.6 2.89 15 12% 15% 13% 31.8 Australia-Manjimup 481 481 50 3 17 160.3 Australia-Busselton 381 381 39 1.5 26 254.0
Nitrogen Soil properties Intensity of the response
Impact correlated to a loading
index (N in residues/ [N] in soil)
Generalisation, meta-analysis from
different networks in the world
Achat et al. 2015 Mainly:
- ‘‘North American long-term soil productivity’’ study (LTSP
network)
- Experiment network in Scandinavia
- ‘‘Site Management and
Productivity in Tropical Plantation Forests’’ network (CIFOR project)
43% in North America (29% in USA, 14% in Canada)
45% in Europe (35% from Scandinavia)
Consequences on nutrient outputs (data compilation from 230 articles, 749 case studies)
Main harvest
treatments considered in the meta-analysis.
Conventional stem-only harvest (S(WB), control) compared to different types of intensive removals or to stem wood harvest (S(W), stem bark left on site; mitigation measure).
Generalisation, meta-analysis from
different networks in the world
Generalisation, meta-analysis from
different networks in the world
Achat et al. 2015
Increases in nutrient exportation (% changes) Nutrient exportation as % of nutrient socks in soils (0-80 cm)
Examples for: Treatment S(WB)B vs S(WB): hatched boxplots Treatment S(WB)BF vs S(WB): solid boxplots
Generalisation, meta-analysis from
different networks in the world
Achat et al. 2015
Increases in nutrient exportation (% changes): relationships with stand age
S(WB)BF
Open circle, broadleaf trees; grey square, sparse canopy coniferous (mainly Pinus, also Larix or Agathis); black triangle, dense canopy coniferous (Picea, Abies and Pseudotsuga).
Generalisation, meta-analysis from
different networks in the world
Achat et al. 2015
mean changes for S(WB)BF vs S(WB
-40 % in wood debris, -10% in forest floor and
deep soils -6 to -12% in total N, P, Ca; -8 to -17% available soil P and CEC, S/T -0.2% in soil pH -8% in microbial activity; -23 to -37% in enzymatic activity -27% in net N mineralization fluxes -3 to -7% in tree growth
Toward an optimized chain for the sustainable use of
forest biomass for energy
Bilot 2015
Soil fertility, soil biodiversity
Sustainabilit
y
Energy
produced
Energetic issue
Energy used to harvest trees Nutrient Exportatio nsToward an optimized chain for the sustainable use of
forest biomass for energy
Modified from Bilot 2015
Tree and stand growth
Harvesting decisions (management- and/or demand- driven) Machine used – Men/month – Fuel – etc…
Biomass, nutrient content in the different
compartments
Energetic caracterisation of the exported material
Nutrient exportation Energy used
during the process • Energy used during
the harvest
• Exported Biomass and
Nutrient content; Humidity Energy produced (ex by pellets) • HHV • Ash content CAPSIS ForEnerChips
• Impact on soil fertility,
soil biodiversity
• Remediation
by ashes
• Ashes production
Critical point 1 : Site effect on nutrient concentration in the tree compartments
Critical point 2 : Knowledge on the energy used in a given harvesting operation
Critical point 3 : Conversion matrix to assess PCI and Ash content
Critical point 4 : Indicators on the impact, responses curves Critical point 5 : Non desirable elements in ashes, impact on ecosystem functionning
Toward an optimized chain for the sustainable use of
forest biomass for energy
Critical point 1 : Site effect on nutrient concentration in the tree compartmentsWernsdörfer et al. 2014 N ( g/k g), wo od +b ark 0 1 2 3 4 5 6 Section diameter (cm) 0 10 20 30 40 Measured Predicted N ( g/k g) 0 2 4 6 8 10 12 14 16 Section diameter (cm) 0 10 20 30 40 Wood measured Bark measured Wood predicted Bark predicted Conc. Wood Conc. Bark Conc. Tot (Wood + Bark)
Size of the compartment
Site effect on the curve – not directly related to soil concentrations
M-POETE, A Mobile-Platform for the Observation and the Experimentation in
Terrestrial Ecosystems (Zeller et al)
Infra-red spectrometry in situ
Translation of the curves (site effect) by making few measurements on the field
Toward an optimized chain for the sustainable use of
forest biomass for energy
Critical point 2 : Knowledge on the energy used in a given harvesting operationBilot 2015
Simulation of
different
scenarios at each
step from the
Toward an optimized chain for the sustainable use of
forest biomass for energy
Critical point 3 : Conversion matrix to assess HHV and Ash contentWoo
d
ener
gy
prod
uctio
n
chain
Ecology, Biogeochemistry
Energy
C N S P K Ca Mg Mn Na Al C, H, O, N "Dry material": 65°C "Dry material": 103°C
Heating value, Ashes
Bilot et al.
Toward an optimized chain for the sustainable use of
forest biomass for energy
Critical point 4 : Indicators on the impact of increased harvest on tree growth, responses curvesCritical point 5 : Non desirable elements (such as heavy metals) in ashes, impact on ecosystem functioning
Two projects have started in 2014, funded by the French
environmental and energy management agency (ADEME)
Ø
INSENSE: Ecosystems sensitivity indicators to increased
biomass removal in forests
Ø
