October 29, 2014 1

Long-term monitoring of rangelands Impacts of fire, tree cutting and livestock grazing on

carbon sequestration in West Africa

Jonas Koala1,2, Mohammed Said2, Louis Sawadogo1, Patrice Savadogo1, Didier Zida1, Ermias Aynekulu3 and de Leeuw, Jan3

1Institut de l'Environnement et de Recherches Agricoles (INEREA)

2International Livestock Research Institute (ILRI), 3World Agroforestry (ICRAF)

6TH All Africa Conference of Animal Agriculture (AACAA), KICC,

Nairobi, 27th – 30th October, 2014

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Background

A critical pre-requisite to managing savanna woodland

for carbon storage and sequestration is a good

knowledge about tree and shrub biomass.

Providing accurate measurements of carbon stock is

difficult without precise measurements of biomass.

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Shrub savanna

Agroforestry parkland Tree and shrub savanna

Tree savanna

Agent of vegetation dynamic

Fire Grazing

Tree cutting

Long term monitoring of tree growth at plot level

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Study sites locations

Experimental design

Each experimental site

18ha

Split into 8 blocks

4 blocks fenced to

exclude (non-grazed)

and the other four

were open for grazing

Each block further

divided 8 plots of 0.25

ha (50 x 50m)

separated from each

other by 20–30m fire-

breaks

Long-term monitoring of tree

growth at plot level

• Every five year:

complete

inventory of the

trees on each plot

(measurement of

dbh, height, crown

area)

• Once a year

monitoring of the

regeneration

DbH

Dbase

Height

Evaluation of grass biomass

Once a year monitoring of the grass layer

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Above ground biomass

Species specific equations were

developed for

Acacia dudgeoni

Acacia macrostachya,

A. leiocarpa,

C.ghasalense,

C. glutinosum,

C. micranthum,

C. nigricans,

C.febrifuga,

D. microcarpum,

E.africana,

P. thonningii

V. paradoxa

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12

13

0 1 2 3 4 5 6 7

0

1

2

3

4

5

6

7

Observed (Log)

Pre

dict

ed (L

og)

R-sq=0.900 Res.df=93 F=218.7 p<0.001 SEE=0.318

Wt=0.213+0.132Db+0.204Dbh+0.0007H-0.005DbxDbh

C. nigricans

1 2 3 4 5 6 7

1

2

3

4

5

6

7

Observed (Log)

Pre

dic

ted

(Lo

g)

R-sq=0.731 Res.df=1170 F=532.8 p<0.001 SEE=0.352

Wt=0.758+0.028Db+0.237Dbh+0.0009H-0.003DbxDbh

+0.0001DbxH-0.0002DbhxH

D. microcarpum

2 4 6 8

2

4

6

8

Observed (Log)

Pre

dict

ed (L

og)

R-sq=0.905 Res.df=112 F=162.8 p<0.001 SEE=0.401

Wt=-0.889+0.107Db+0.304Dbh+0.004H-0.006DbxDbh-0.00002DbxH

-0.0002DbhxH+0.000004DbxDbhxH

A. leiocarpa

1 2 3 4 5 6

1

2

3

4

5

6

Observed (Log)

Pre

dict

ed (L

og)

R-sq=0.693 Res.df=438 F=250.2 p<0.001 SEE=0.461

Wt=0.358+0.100Db+0.169Dbh+0.001H-0.004DbxDbh

P. thonningii

Allometric equations for above ground biomass of some key species of savanna woodland

Source: Didier

Direct roots biomass

assessment Monolith

extraction to assess disturbances effects on root biomass at plot level

Excavation to assess in species Anogeissus

leiocarpa, Detarium

microcarpum;

Piliostigma

thonningii and

Vitellaria paradoxa

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Allometric equations for Belowground biomass of Four key species of savanna woodland

Source: Koala et al. in prep

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Treatments Total roots biomass weight (t/ha)

Mean±SE CI 95 %

LS US

CONTROL 16.79±1.55 13.745 19.837

Grazing 11.09±1.76 7.638 14.545

Early Fire 17.37±1.69 14.038 20.693

Cutting 12.09±1.85 8.471 15.719

Grazing x Fire 15.66±1.84 12.041 19.278

Grazing x Cutting 17.54±1.85 13.908 21.168

Fire x Cutting 16.53±1.58 13.429 19.636

Grazing x Fire x Cutting 11.69±2.16 7.453 15.937

Total roots biomass at layer 0-50 cm in savanna woodland based on grazing, early fire and selective trees cutting and

their interactions

Source: Koala et al. in prep

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Source: Satcie Wolney Natural Capital Project

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Source: Satcie Wolney Natural Capital Project

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Source: Satcie Wolney Natural Capital Project

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