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PK06:Distribution of Soil Organisms in Diverse Tropical Ecosystems: The Impact of Land Use on Diversity
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PK06:Distribution of Soil Organisms in Diverse Tropical Ecosystems: The Impact of Land Use on Diversity

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A presentation by Dr. Peter Okoth

A presentation by Dr. Peter Okoth

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  • 1. 5/27/2010 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 1
  • 2. 5/27/2010 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 2
  • 3. 5/27/2010 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 3
  • 4. 5/27/2010 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. 4
  • 5. 5/27/2010 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 5
  • 6. 5/27/2010 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 6