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Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Logging in central Africa: extent and impact
S. Gourlet-Fleury, F. Baya, D. Beina, D.Y. Ouédraogo, A. Fayolle, F. Mortier, F. Bénédet, D. Closset-Kopp, G. Decocq, A. Billand
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Logging in central Africa: where?
Six main countries:
404.8 106 ha
Forest area:
162.0 106 ha (40%)
Lowland rainforests:
142.2 106 ha (88% of
forested area)
Land Cover Map of Africa (GLC 2000) – DG-JRC
Data source: OFAC / COMIFAC
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Logging in central Africa: where?
Rainforests area (106 ha) – Total: 162.0 106 ha
98.921.1
18.5
16.9
4.6 2.0 DRC
Gabon
Congo
Cameroon
CAR
Equatorial Guinea
Data source: OFAC / COMIFAC
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Logging in central Africa: where?
Source: de Wasseige & Wala Etina, EDF 2010 (in press)
OFAC/COMIFAC
Forest area:
162.0 106 ha
Production forests:
62.0 106 ha* (38% of
forested area)
Allocated to
concessions (large):
39.0 106 ha (24% of
forested area)
* Estimated from ITTO (2011)
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Logging in central Africa: what and how
much?
Contribution of the formal forestry sector to GDP: between
0.2 (Equatorial Guinea) and ≥ 6% (Cameroon, CAR)
Okoumé (Aukoumea klaineana,
Burseraceae) – 32%
Sapelli (Entandrophragma cylindricum,
Meliaceae) – 16%
Ayous (Triplochiton scleroxylon,
Malvaceae) – 11%
Azobé (Lophira alata, Ochnaceae)
Iroko (Milicia excelsa, Moraceae)
Aniégré (Aningeria sp., Sapotaceae)
Fifty commercial species, but ~10 species most valued:
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Harvested timber volume (106 m3) – Total: 8.4 106 m3
98.921.1
18.5
16.9
4.6 2.0 DRC
Gabon
Congo
Cameroon
CAR
Equatorial Guinea
Rainforests area (106 ha)
Productivity:
± 17.1 m3 ha-1 AHA
(7 m3 in CAR to
45 m3 in Gabon)
0.3
3.4
1.3
2.3
0.50.5
DRC
Gabon
Congo
Cameroon
CAR
Equatorial Guinea
Total annual harvestable area (AHA): ~ 600 000 ha
Logging in central Africa: what and how
much?
2007
Data source: OFAC / COMIFAC
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Logging in central Africa: how?
Management plans mandatory in all forest codes
Felling cycles: 25 to 50 years (most often 30 years)
Minimum harvesting diameters / species (Cameroon, Congo, DRC, Gabon):
most often between 60 and 90 cm dbh
Managed or under management process: 26.1 106 ha (67% of
concessions area)
3.0 106 ha FSC certified in 2008 (Cameroun, Congo, Gabon)
General problem: still limited knowledge on the mid and long-term
impacts of timber logging, and concerns about its sustainability
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Settled in 1982,
110 km SW of Bangui
French government
massively investing in
forest management in
Central Africa,
needing:
Quantified data on
the effects of
logging
Better knowledge
on stands and tree
species dynamics
Assessing the impact of logging: the M’Baïki
Experimental Station
Land Cover Map of Africa (GLC 2000) – DG-JRC
M’Baïki experimental station
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Semi-deciduous
rainforest (Malvaceae,
Ulmaceae, Meliaceae,
Sapotaceae)
Mean annual rainfall:
1738 mm (1982-2007)
Large plateau (500-
600 m a.s.l.), acrisols
Assessing the impact of logging: the M’Baïki
Experimental Station
Land Cover Map of Africa (GLC 2000) – DG-JRC
M’Baïki experimental station
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
10 plots, 9 ha each
All trees ≥ 10 cm dbh mapped and
monitored every year in the 4 ha
core zone (≥ 35 000 trees)
More than 310 tree species, mean
species density (r): 120 sp. ha-1
Three treatments implemented
between 1984 and 1987:
Control (3 plots)
Timber logging (3 plots)
Timber logging + thinning (4 plots)
Assessing the impact of logging: the M’Baïki
Experimental Station
Bedel & al. (1998)
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Main characteristics of control plots
Commercial species (40):
22% of tree number
40% of basal area
47% of standing volume
(81% of volume ≥ 80 cm dbh)
0
50
100
150
200
250
300
350
400
10-20 20-30 30-40 40-50 50-60 60-70 70-80 >=80
Classes de diamètre (cm)
Eff
ec
tif
(/h
a)
1984
2005
0
20
40
60
80
100
120
10-20 20-30 30-40 40-50 50-60 60-70 70-80 >=80
Classes de diamètre (cm)
Vo
lum
e s
ur
pie
d (
m3
/ha
)
1984
2005
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Silvicultural treatments
Treatments N
(ha-1)
G
(m2 ha-1)
V
(m3 ha-1)
% G
eliminated
Logging 4 4 66 23%
Logging + thinning 23 8.5 101 34%
Logging: ≥ 80 cm dbh
Thinning: ≥ 50 cm dbh
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Impact of treatments: productivity and
recovery
Sapelli (E. cylindricum) Ayous (T. scleroxylon)
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
1984 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
Années
Eff
ecti
f d
e sa
pel
lis
>=
80
cm d
bh
(/h
a)
Observations
Prédictions
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
Initia
l 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
Années
Eff
ecti
f d
'ayo
us
>=
80
cm d
bh
(/h
a)
Observations
Prédictions
Logged: 1.4 t ha-1, 20.3 m3 ha-1
Volume recoverable within 30
years: 13%
Logged: 1.6 t ha-1, 28.3 m3 ha-1
Volume recoverable within 30
years: 27%
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Impact of logging in Central African semi-
deciduous rainforests
Little impact at first cut:
Volume and biomass quickly recover
Little impact on floristic diversity
However, felling cycles too short (MHD too low?) to
allow commercial stock recovery
Post-logging silvicultural operations will be needed to
ensure sustainability (of the same species)
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Knowledge still needed
Long-term monitoring is crucial (models need long-term data)
1980 2000 2020 2040 2060 2080 2100
0.0
0.5
1.0
1.5
2.0
Year
Num
ber
of
trees
80 c
m d
bh (
ha
1)
Plain line is the evolution predicted by a Usher matrix
model, with its 95% confidence limits in grey.
Around 200 trees are necessary to
achieve a precision of 10% to 30%
on the stock recovery rate, for an
risk of 5 to 20%
Sapelli (5.6 trees/ha) => 36 ha
Dibétou (1.3 trees/ha) => 154 ha
Sipo (0.2 trees/ha) => 1000 ha !!!
Too large areas needed can be partly
compensated by a greater number of re-
measurements (Picard & Gourlet-Fleury, 2008)
Sapelli (Picard & al., 2008)
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Knowledge still needed
Spatial network of plots aiming at dissociating logging and
environmental effects is crucial => DynAfFor project
M’Baïki
Yoko/Biaro
Couples of 400 ha plots,
combined with 9 ha plots
One control / one logged
after 4 years
(At least) four other sites
needed to complete the
DynAfFor network …
0
50
100
150
200
250
300
350
1 2 3 4 5 6 7 8 9 10 11 12
Mois
To
tal d
es
pré
cip
ita
tio
ns
(m
m)
LISALA
BUTA
OUESSO
IMPFONDO
0
50
100
150
200
250
300
350
1 2 3 4 5 6 7 8 9 10 11 12
Mois
To
tal p
réc
ipit
ati
on
s (
mm
)
PORT FRANCQUI
Global Change, Deforestation and the Future of African rainforests - Oxford, 4-6 January 2012
Knowledge still needed
Better knowledge of ecological requirements and history of
vegetation and disturbance is crucial => CoForChange project
23 forest concessions
Around 6 millions ha of
management inventories
Multi-disciplinary study of the
determinants of spatio-
temporal tree species
distribution