1. Legume-based fallows for restoring the community of soil macro-
invertebrates in semi-deciduous forest areas of Côte d’Ivoire
Arnauth M. GUEI1*, Armand W. KONE1, Jérome TONDOH 2, Pascal K.T. ANGUI1 , Yao Tano3
1Université d’Abobo-Adjamé, 02 BP 801 Abidjan 02, Côte d’Ivoire
2CIAT-TSBF, Institut d’Economie Rurale, CRRA de Sotuba, Laboratoire Sol-Eau-Plante, BP 262 Bamako, Mali
3Université de Cocody , 22 B.P. 582 Abidjan 22, Côte d’Ivoire
* E-mail:gueiarnauthmartinez@yahoo.fr
Conservation and Sustainable Management of
Below Ground Biodiveristy
Introduction
Soils house scores of organisms diverse in both the number of species recorded and the roles that they play in the
ecosystem (Lavelle et al., 2004). Soil macrofauna, such as earthworms, have a high potential to be used as bioindicators
of soil quality, as they are in direct contact with the soil. They allow for a sound assessment of environmental hazards
(Lavelle & Spain, 2001). Thus, the management of soil fauna must not be ignored in promoting sustainable agriculture
(Brussaard et al., 2007). The use of legumes to improve fallows is in total agreement with that of soil macro-
invertebrates, as this can greatly contribute to soil organic matter conservation and cover through an abundant production
of litter which is a food source for soil-born organisms (Lavelle et al., 2003; Koné et al., 2008).
Objective
The study aims to determine the potential of soil macro-invertebrates, especially earthworms as indicators of soil Natural fallow Mucuna pruriens variety utilis
biodiversity restoration in legume-based fallows.
Experimental plots and soil macrofauna sampling
The study was carried out in a semi-deciduous forest margin in mid-West Côte d’Ivoire (6° 30’N, 5° 31’W). Sampling for
soil macrofauna was done in experimental plots installed for legume and foodcrop trials, in the benchmark site. They were
concerned with 3 types of fallow-based legume crops of short duration (Mucuna pruriens var utilis, Cajanus cajan and
Pueraria phaseoloides). There were 4 plots of Cajanus cajans and 4 plots of Pueraria phaseoloides, while Mucuna
pruriens was grown in only one plot. Each plot was divided into two subplots of 25 x 25m. One subplot was planted with
one legume species and the other subplot consisted in a natural fallow (check). Three soil monoliths (25 x 25 x 20 cm) Cajanus cajan Pueraria phaseoloides
were randomly dug in each subplot.
Natural and legume fallows plots
Results
1. Soil macro-invertebrate community
2. Legumes impact on soil macro-invertebrate abundance
Soil macrofauna community, collected in all experimental plots, consisted in 12 taxa, namely earthworms, ants, termites,
spiders, coleoptera, diplopoda, chilopoda, hemiptera, dermaptera, isopoda, coleoptera and diptera larvae. Earthworm 1000 Macrofauna density (individual.m.-2) a
communities comprised 17 species, distributed among 6 genera. Pueraria phaseoloides (Pp) hosted the highest total
800 a
number of earthworm species. This legume species was followed by C. cajan (Cc), that hosted twice as much species as a
M. pruriens. Pueraria phaseoloides and M. pruriens (Mp) fallows hosted more species than the corresponding check 600 a 629.3
plots. b 620.7 Legume
400 426.7 465.3 b
Control
200 304 310.7
0
Pueraria Cajanus cajan Mucuna pruriens
phaseoloides
Legume plots
250 Earthworm density (individual.m.-2)
200 a a a
a a
150 b
160 150.7 165.3 Legume
100
118.7 136 138.7 Control
50
0
Pueraria Cajanus cajan Mucuna pruriens
phaseoloides
Legume plots
3. Legumes impact on soil macro-invertebrate diversity
Taxonomic group diversity (Shannon index)
4. Impact of legume species on soil macro-invertebrate community 2.5
a a
2.0
a
a- Macro-invertebrates b- Earthworms a a a
1 3 1 5
1.5
Axis 2 (23%)
2.03 2.14
Axis 2 (30%)
-1 1 -3 3 -1 1 -5 5
Axis 2 (23%)
-1 -3 -1 -5
Legume
Biomass 1.0 1.75 1.51
1.22 Control
C. cajan plots
0.5 1.62
Taxonomic richness
C. cajan plots
Shannon index Shannon index
Axis 2 (30%)
Species richness
0.0
Axis 1 (35%) Axis 1 (35%) Axis 1 (59%) Axis 1 (59%)
Pueraria Cajanus cajan Mucuna pruriens
Density Equitability phaseoloides
P. phaseoloides plots
Equitability M. pruriens plots Legume plots
Biomass P. phaseoloides plots
M. pruriens plots
Density
P = 0.009
P = 0.001
Earthworm diversity (Shannon index)
The first two axes accounted for 65 % of the total inertia. The distribution of the inertia indicated that the first two axes 3.0 a
a a
Macrofauna abundance correlated negatively to axis 1, accounted for 82 % of total inertia. Excepted for equitability, 2.5
all earthworm communities were negatively correlated to 2.0 b
whereas diversity correlated positively to the same axis. a
2.72 a
Biomass, taxonomic richness and Shannon index were axis 1. Earthworm species richness and Shannon index were 1.5 2.43 Legume
2.42
positively correlated to axis 2, while density and equitability positively correlated to axis 2, while abundance and 1.0 1.59 1.48
1.39 Control
were negatively correlated to this axis. Legume plots equitability were negatively correlated. The projection of 0.5
projection revealed a significant opposition between the 3 legume plots revealed a significant opposition between the 3 0.0
legume species. M. pruriens and C. cajan fallows restored legume-based fallows. P. phaseoloides restored earthworm Pueraria Cajanus cajan Mucuna pruriens
most macro-invertebrates communities and biomass, abundance, while C. cajan fallow hosted the highest species phaseoloides
respectively. While P. phaseoloides produced the highest diversity. Though M. pruriens hosted the lowest diversity, Legume plots
taxonomic diversity. the individuals were fairly evenly distributed into the
different species.
Conclusion Acknowledgements
The study assessed the potential of legumes to improve soil macro-invertebrate biodiversity. Of the 3 legume-based This study is a part of the N°GF/2715-2 projet, supported by FEM/PNUE. The
fallows, P. phaseoloides and M. pruriens restored soil macrofauna biodiversity more than C. cajan, although the increase authors are grateful to the local coordinating committee, the farmers from
was not always significant. Hence, P. phaseolides fallow was the most effective in enhancing soil macrofauna biodiversity Goulikao and field technicians for their kind assistance throughout this
after 9 months of growth. investigation.
References
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