Peter Okoth presented on the distribution of soil organisms in diverse tropical ecosystems and the impact of land use on diversity. The study aimed to better understand the relationship between soil organisms and different land uses, and to use that knowledge to support ecosystem services. The hypothesis was that soil biological diversity decreases with land use intensification and change, from forests to croplands. Samples were collected from sites in several countries representing a land use gradient, and were analyzed for macro/meso fauna and microbes. Results showed significant differences in organism distributions between land uses, and relationships between certain organisms and soil chemical properties.

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List of contributors
Distribution of Soil Organisms in
Diverse Tropical Ecosystems: The Peter Okoth, Joseph Mung’atu, Fatima
Moriera, Jeroen Huising, Fransis Susilo,
Impact of Land Use on Diversity Brazil
Mary Gikungu, Sheila Okoth, Brian Cote d’Ivoire
Isabirye, Juvenil E. Cares, Souleymane
Peter Okoth
Mexico Konate, Anne Akol, Si
K t A Ak l Simoneta N
t Negrete-
t
Tropical Soil Biology and Fertility Institute of
Yankelevich, Nancy Karanja David
the International Centre for Tropical Uganda
Agriculture (TSBF-CIAT) Bignell, Chandrasekhara U.M, Maikhuri
Indonesia R.K, Jan Lagerlof, Joyce Jefwa
India
Kenya
Presentation Outline
Introduction
• Introduction
• Definitions
• Objectives
• Hypothesis
• Methodology
• Results
• Discussions
• Conclusions Macro and meso-fauna
Justification
• Need for better understanding of the relationship between soil
organisms and land use differences.
Definitions
• Organisms could offer basis for regulating, suporting and
provisioning of ecosystem services (e.g. decomposition, pest
& disease control, food, carbon sequestration, etc)
• Need for increasing agricultural productivity through:
enhanced nutrient release, increased nutrient cycling,
decomposition, symbiosis (e.g. nitrogen fixation),
increased root surface area, fungal diseases control
, g
(antagonistic fungi), enzyme production, pests control (e.g.
bacillus)
Isolation and testing
of effective AMF
strains, Mexico
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Below-Ground Biodiversity Land Use
An assemblage of different soil biota Land use in this presentation is defined at
broad categories almost synonumous with
separated by taxonomic differences and
land cover definitions and include: forests
forests,
or functional differences and assessed tree-based systems (including agroforestry
by using diversity indicies. systems), grasslands, fallows and
croplands.
Objectives
Objectives
• Create better knowledge and
understanding of the distribution of soil
organisms in different land use kinds.
• Use knowledge gained for designing
methods for supporting, regulating and
provisioning of ecosystem services.
Soil biological diversity decreases with
Hypothesis land use intensification & change
Diversity
Forests Tree based
systems Grasslands Fallow Croplands
Land Use Change & Intensification
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Field layout
Methodology 13 cm
6 metres 6 metres
2 metres
20 metres
Transect
8 metres
6 metres
3 metres
Macro and meso-fauna
Microbes, i.e, bacteria and fungi
from composite soil samples
For more details-see Manual on Tropical Soil Biology
Data Analysis Results & Discussions
Global analysis of data collected in Brazil, Cote
d'Ivoire, India, Indonesia, Kenya, Mexico & Uganda.
Comparison of means after an ANOVA
PCA for soil-biota analysis
The computation of means was done using the
GENSTAT software Version 10 (Rothamsted
Experimental Station, UK, 2007).
Relationship between BGBD and
soil chemical properties-Indonesia Soil organisms Vs Land Use
Eigenvalues d = 0.5
P205
pH
PPF
AMF
Mg Collembolla
Bsat
OM
Earthworms
Beetles Termites
Sca Ant Nematode
N
Ca K Na CEC
Monte Carlo Significance test
p value=0.009
Observation=0.2882
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Relationship with soil chemical
properties Fungi distribution
Beetles, ants and earthworms correlate more with
Calcium, Magnesium and high Base Saturation.
Termites are more associated with high organic
matter.
matter
Nematodes associated more with Nitrogen.
Plant pathogenic fungi, arbuscular mycorrhizal fungi
and collembola associated more with Phosphorous.
Arbuscular mycorrhizal fungi (AMF) Plant pathogenic Fungi
AMF Plant Pathogenic Fungi
Pythium spp. tend to be very generalistic and
• Sensitive to human disturbance e.g.
unspecific in their host range.
higher sporulation and diversity in tree
based systems compared to forests. Phytophthora spp. are generally more host-specific.
• Sensitive to root turn-over i.e. comparing
turn over i e
For this reason, Pythium spp. and their relatives,
perrenials and annuals (grasslands (i.e., Rhizoctonia, Fusarium & Phytophthora spp) are
versus forests). more devastating in the root rot they cause in crops.
• Sensitive to intesity of chemical used
Crop rotation alone will often not eradicate the
(i.e., spores depressed in croplands). pathogen
Legume Nodulating Bacteria LNB
Distribution based on presence of
leguminous plants above-ground though
more in croplands and tree based systems
most probably due to introduced legumes
legumes.
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Macro-fauna in general Beetles & Earthworms
Beetles Earthworms
Earthworms, termites, ants, beetles, spiders, etc
Ants & Termites Macro-fauna
Distribution determined mainly by less
Ants Termites
disturbed habitats and availability of food
sources and organic matter .
Meso-fauna Meso fauna & Nematodes
Inhabit fallows more than the other land use
kinds.
Proliferation based more on less habitat
disturbance.
Nematodes are almost equally distributed in
forests, grasslands and in croplands. Their
distribution almost similar to the PPF.
Meso-fauna Nematodes
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Conclusions Message
Soil biota in general change with land use kinds.
The direction of change is however not in any one
direction. Tree based systems seems to favour the
highest diversity.
The b o a see s to a g themselves with nutrients,
e biota seems o align e se es u e s,
land use, food chains, their individual functions and
habitats.
The trends show that soil biota can be used to
further understand their niches including
opportunities in ecosystems services.
Acknowledgement Thanking
• Global Environment Facility (GEF) for the
financial support.
• UNEP for implementation support.
• Diversitas for the conference organization.
• SIDA for the sponsoring this particular
presentation.
• CIAT Director General and TSBF Director for
making the work possible in good environment.
• Countries and partners in: Brazil, Cote d’Ivoire,
India, Indonesia, Kenya, Mexico and Uganda
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