Hidden capital: harnessing belowground biodiversity for sustainable agricultural landscapes
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This document discusses belowground biodiversity and its importance for sustainable agriculture. It notes that human activities over the last 50 years have significantly degraded ecosystems while increasing human well-being. Belowground biodiversity is much greater than aboveground biodiversity but remains poorly understood due to its complexity. Studying soil organisms is challenging but important functional groups include decomposers, symbionts, and those involved in carbon, nitrogen and nutrient transformations. Molecular techniques are revealing greater unknown diversity in soil. Trees can increase the abundance and activity of beneficial soil biota in agricultural landscapes, mediating some of their effects on crops and enhancing ecosystem services. Further research on belowground biodiversity is needed to improve agroecosystem management and soil health.
Hidden capital: harnessing belowground biodiversity for sustainable agricultural landscapes
- 1. Hidden Capital: Harnessing Belowground Biodiversity for Sustainable Agricultural Landscapes Edmundo Barrios Peter Mortimer Science Forum 2011, Nairobi
- 2. OUTLINE 1. Degrading our Natural capital 2. Belowground Biodiversity Inside Out 3. Soil Based-Ecosystem Functions/Services 4. BGBD and Agroecosystem Management 5. Biological Indicators of Soil Health ICRAF- china China 6. Future Challenges
- 3. 1. Degrading our Natural Capital
- 4. Earth experiencing DIRECTIONAL CHANGES in many drivers of human-environment processes Steffen et al. 2004 IGBP
- 5. MA Findings in a Nutshell Growing demands for food, freshwater, timber, fiber & fuel Reversal Last 50 yrs Efforts Greatest Degradation of demand Ecosystem Ecosystems & significant Change by Biodiversity Loss changes in Humans Policies, Net gains in human Institutions, well being & economic Practices development have been possible at the cost of degradation of other ecosystem services Millennium Ecosystem Assessment, 2005
- 6. DEFORESTATION AND BIODIVERSITY LOSS BRAZILIAN AMAZON (1988-2008) 3.5 Million ha deforested per year 3.0 2.5 2.0 1.5 1.0 0.5 0 Nepstad, 2007 WWF-UNFCC
- 7. Are we looking at the tip of the iceberg? Aboveground biodiversity Belowground biodiversity
- 8. 1. Degrading our Natural capital 2. Belowground Biodiversity and Function
- 9. BIODIVERSITY IN AGRICULTURAL LANDSCAPES Planned and managed AGBD aboveground biodiversity Above-ground: planned, managed biodiversity ? BGBD Unplanned, unmanaged ? Below-ground: unplanned, unmanaged biodiversity belowground biodiversity ? Diversitas 2005
- 10. Limited knowledge about soil biota BLACK BOX APPROACH INPUTS OUTPUTS
- 11. +BGBD likely higher than Aboveground Modif. Wall et al 2001, Barrios 2007 EcolEcon
- 12. OPENING THE BLACK BOX BGBD SOIL PROCESSES INPUTS OUTPUTS
- 13. Soil biota must be selectively studied because: • There is no single method for studying soil biodiversity • It is not possible to study all groups simultaneously
- 14. Internationally accepted standard methods for the inventory of BGBD Handbook with methods for the inventory of BGBD • General guidelines and principles • Sampling strategies • Major functional groups of soil organisms • Land use Moreira et al., 2008
- 15. KEY FUNCTIONAL GROUPS OF SOIL BIOTA Maize Legume Decomposers Micro-symbionts e.g. cellulose degraders mycorrhizal N-fixing Fungi Bacteria Macrofauna Microregulators C&N transformers (Ecosystem Engineers) e.g.methanogens, – Earthworms Nematodes nitrifiers, denitrifiers – Termites Pests and Diseases e.g. fungi, invertebrates
- 16. BACTERIAL DIVERSITY IN SOIL 100 g Soil 5 x 1011 Colonies DNA Extraction on Agar Plates 200 Isolates 66 Cultured Species 13,000 Genetic Species Torsvik et al., 1994
- 17. Molecular Approaches ABUNDANCE RICHNESS ACTIVITY Microscopic counts PLFA Respiration Viable plate counts FAME C mineralization MPN N/P mineralization Microbial biomass Soil enzymes ATP FUNCTION Soil Sample FISH In situ PCR RICHNESS/FUNCTION Re-association Hybridization Nucleic Acids DNA RNA Cloning RFLP Microarrays PCR RT-PCR RICHNESS Excise Screening bands Southern Community Fingerprinting Oligonucleotide blot ARDRA ITS-PCR DGGE Probes RAPD T-RFLP REP-PCR Sequencing Probe design Accession PHYLOGENY Sequence database Thies, 2004
- 18. BARCODED PYROSEQUENCING From 118 soil samples (4 Sentinel sites in Tanzania) 27% Bacterial & Archeal sequences did not match public databases and thus likely unknown SENTINEL SITES Wall & Fierer, 2011
- 19. BUT SOIL ORGANISMS ARE NOT EVERYWHERE Environmental influences Disturbance Population processes Fine-scale effects of roots, organic Reproduction particles, soil aggregates and soil Mortality micromorphology 1m Active dispersal Competition Plot- to field-scale effects of burrowing Predation animals, within-field Mutualism moisture gradients, individual plants and 100 m plant communities Passive dispersal Landscape-scale gradients of texture, soil carbon, topography and vegetation systems 1 km Ettema & Wardle, 2002 TrendsEcolEvol
- 20. Some effects of trees are mediated through impact on soil biota – trees increase abundance Mean density of different soil biota and calculated response ratios Agroforestry Agriculture RR References Soil macrofauna (indiv m-2) (indiv m-2) Earthworms 54.4 17.6 3.1 1,2,3,4,5,6 Beetles 20.9 9.6 2.2 1,2,5 Centipedes 2.7 0.5 5.6 1,2,5 Termites 90.7 81.0 1.1 1,2,5 Ants 23.2 8.6 2.7 1,2,5 Soil mesofauna (indiv m-2) (indiv m-2) Collembola 3890.1 2000.7 1.9 7 Mites 5100.7 1860.1 2.7 7 Soil microfauna (indiv liter-1) (indiv liter-1) Non-parasitic nematodes 2922 1288 2.3 8 Parasitic nematodes 203.7 211.5 1 8 Barrios, Sileshi, Shepherd, Sinclair 2011
- 21. Some effects of trees are mediated through impact on soil biota – trees increase activity Greater soil biological activity (earthworms) near trees but effect greater for some tree species than others Pruned trees Free growing trees Earthworm cast weight Sample with no earthworm casts Pauli et al 2010 Pedobiologia
- 22. TREES AS HOTSPOTS OF BIOLOGICAL ACTIVITY IN AGRICULTURAL LANDSCAPES Protection allowing survival during stress periods Barrios et al. 2011
- 23. TREES AS HOTSPOTS OF BIOLOGICAL ACTIVITY IN AGRICULTURAL LANDSCAPES Rapid recolonization and function Barrios et al. 2011
- 24. Mapping BGBD and function in agricultural landscapes Kiberashi Sentinel Site – Central Tanzania Developing and testing spatially-explicit approaches for soil macrofauna Tree density and cover GRP2-U.Nairobi-GRP4 collaboration
- 25. 1. Degrading our Natural capital 2. Belowground biodiversity and function 3. Soil-Based Ecosystem Functions and Services
- 26. ECOSYSTEM SERVICES Goods produced or provided by ecosystems Services that maintain the conditions for life on earth Benefits obtained from regulation of ecosystem processes Non-material benefits obtained from ecosystems Millennium Ecosystem Assessment , 2005
- 27. SOIL BIOLOGICAL FUNCTION AND THE PROVISION OF ECOSYSTEM SERVICES Adapted Kibblewhite et al. 2008, Barrios et al, 2011
- 29. GLOBAL DECOMPOSITION EXPERIMENT Wall et al., 2008 Soil fauna expected to enhance decomposition rates in areas becoming hotter and wetter due to Climate Change
- 30. NUTRIENT CYCLING N-fixation Improved Fallow Agroforestry Systems Chipata - Zambia Barrios et al., 1997 SSSAJ
- 31. Plant traits impact on soil biological processes Parameter Mean† Difference between contrasted treatments NAT vs. Nfix vs. (HQ) Low L+PP/N vs. SES vs. SES vs. Trees No Nfix (LQ) High L+PP/N other Trees NAT LL+LM‡ Dry wt (g kg-1 soil) 1.12 0.26** 0.09 0.10 0.38*** 0.05 Amount (mg kg-1 soil) C 302 44.4 10.7 10.0 85.7** 27.0 N 19.0 -1.03 4.40** 2.84* 8.59*** 8.19*** P 1.00 0.30*** 0.14 0.23** 0.54*** 0.15 Soil N (mg N kg-1 soil) N-NH4+ 5.6 -0.48 1.54* 3.69*** 3.79*** 3.64*** N-NO3- 8.7 -2.35** 6.16*** 3.38*** 7.31*** 8.45*** Inorg N 14.3 -2.83* 7.69*** 7.07*** 11.1*** 12.1*** Aerobic N min (mg N kg-1 soil day-1) 0.37 0.08 0.11* 0.21*** 0.29*** 0.16** Significance levels: * = 0.05, ** = 0.01, *** = 0.001. NAT = natural uncultivated fallow, Nfix = N fixing trees, Nonfix = non N fixing trees, L+PP/N = lignin plus polyphenols/Nitrogen, and SES = planted sesbania fallow. Barrios et al. 1997 SSSAJ
- 32. Soil Structure maintenance HIERARCHICAL MODEL OF AGGREGATION Solid 2000 m Pore Root Hyphae 200 m Aggregates or particles Hyphae 20 m Bacteria Packets of clay particles Microbial debris (humic materials) 2 m Clay particles Clay plates 0.2 m Cemment Tisdall & Oades, 1982
- 33. Soil Structure maintenance AGGREGGATE DYNAMIC MODEL Adapted from Six et al., 2002
- 34. SOIL BIOSTRUCTURE Macroinvertebrates ECOSYSTEM ENGINEERS as much as 1000 Mg/ha/yr Blanchart et al., 1999 Mycorrhizas GLOMALIN >100 m / cc soil Parniske, 2008 Courtesy K.Ritz, NSRI, UK
- 35. GLOMALIN visualized with FITC-coupled MAb32B11 (on 1-2 mm aggregates) Photo: S. Wright Courtesy S.Wright, USDA
- 36. SOIL STRUCTURE-SOIL BIOTA Impact of biological activity on soil aggregate stability Soil Biota Soil Structure Pore distribution influences the distribution and activity of soil microorganisms Young & Crawford, 2004 Science
- 37. SOIL STRUCTURE / WATER DYNAMICS Changes in soil hidrofobicity Induces soil water repellency Influences soil water fluxes Hallet et al. 2009, Pland &Soil Biota Structure Quantity and Quality of Water
- 38. SOIL STRUCTURE: Erosion and C storage Increased stability of soil aggregates to water contact Biota Structure Reduction in C losses Lower soil erosion and greater potential for soil C sequestration Fonte et al., 2010 Geoderma
- 39. Spectral (NIRS) signatures of biogenic structures Bulk soil PC2 Carton termite mounds Ant deposits Earthworm casts PC1 Termite sheathings Organo-mineral termite mounds Hedde et al., 2005
- 40. Biological Population Regulation SOIL FOOD WEBS Hunt et al. 1987 Fatty Acid/13C signature Feeding strategies & diets in situ Ruess & Chamberlain, 2010
- 41. Biological Population Regulation …..less nematodes in prescence of earthworms 600 No worms With worms A Nematodes/pot 500 400 300 B 200 a 100 b 0 6 weeks 12 weeks Lavelle et al., 2004
- 42. Biological Population Regulation Direct effect of gut transit on the viability of eggs in cysts of Heterodera sacchari 3 mm Lavelle et al., 2004
- 43. Biological Population Regulation BNF Striga sp. population > Soil N availability Parasitic Weed Barrios et al., 1998
- 44. Biological Population Regulation Grown is soils infested Inoculation with AMF Striga hermonthica > P availability Reduction in number (30-50%) and biomass (40-63%) de S.hermonthica Lendzemo et al., 2005
- 45. 1. Degrading our Natural capital 2. Belowground biodiversity and function 3. Soil-based Ecosystem Services 4. BGBD and Agroecosystem Management
- 46. AGROECOSYSTEM MANAGEMENT Natural Agroecosystem Ecosystem Intensification Biodiversity and Ecological functions Agrochemicals Petro energy RESULT: biological capacity for system self-regulation Barrios, 2007 EcolEcon
- 47. TWO PATHWAYS FOR THE BIOLOGICAL MANAGEMENT OF SOIL FERTILITY 1. Direct BIOLOGICAL control by inoculation 2. Indirect ECOLOGICAL control by cropping system, plant, organic matter or environmental manipulation.
- 48. SOIL BIOTECHNOLOGIES Practice Target • Nfix Bacteria • N2 fixation • Mycorrhiza • Nutrient uptake • Biological control • Plant health • Rhizobacteria • Plant growth • Macrofauna • Soil structure
- 49. Economic evaluation of BGBD: BNF Worth of N2 fixed by grain legumes in developing countries: US$ 6.7 billion (Hardarson et al., 2003) Brazil, N-fertilizer saving from inoculated soybean: US$ 2.5 billion (Alves et al. , 2003) SSA N-fertilizer saving from promiscuous soybean: US$ 203 million (Chianu et al., 2010)
- 50. EARTHWORMS CAN SIGNIFICANTLY INCREASE CROP YIELDS AND REVENUE Increases: >200% yield 5500 USD/ha Senapati et al. 1996
- 51. Quesungual Slash&Mulch Agroforestry System (QSMAS) 80 Slash 70 and Burn 60 2007 – LSD= ns 2006 – LSD= 1.08 Soil loss (t ha-1) 50 2005 – LSD= 6.59 40 30 30% GREATER 20 SOIL MACROFAUNA 10 QSMAS Secondary ABUNDANCE THAN Forest 0 SECONDARY FOREST 0.14 LSD0.05= 0.015 Available water content (m3 m-3) QSMAS Sec. 0.12 Forest Slash & Burn 0.10 0.08 0.00 Welchez et al. 2008, Castro et al. 2009, Pauli et al. 2011
- 52. Peter Mortimer Three areas of focus ICRAF-Kunming Mushroom harvesting Mine restoration Tree fertilizers
- 53. Alnus nepalensis: A Green Fertilizer N-fixing trees as shade trees • Ecosystem cycling: simple to complex • Multi-tiered approach -soil community analysis -root symbioses -soil nutrition -soil water -crop productivity Does Alnus influence soil nutrition and soil biodiversity?
- 54. Distribution according to altitude
- 55. Simple Complex
- 56. Forest products: sustainable mushroom harvesting • Over harvesting-unsustainable -Ophiocordyceps (Caterpillar fungus) -Matsutake (50% decline in N Yunnan) • Telephora ganbarjun: -3-6 harvests/season -increase 43% by harvest weight and 86% earnings -net income from T. ganbarjun: US$2 million/year
- 58. Succession of mushroom species TIME (YEARS)
- 59. “Ecosystem recycling” 废渣尾矿 粒状磷酸钙 磷石膏
- 60. Soil health is key • Unique opportunity to study soil community succession • Disturbed; processed and relocated soils • Monitor below ground activities and changes: -Soil nutrition -Soil communities • Correlate above ground species with below ground health (or vice versa?)
- 61. Green economy reclamation Ecological Reclamation
- 62. Full cycle
- 63. 1. Degrading our Natural capital 2. Belowground biodiversity and function 3. Soil-based Ecosystem Services 4. BGBD and Agroecosystem Management 5. Biological indicators of Soil Health
- 64. PLANTS AS LOCAL INDICATORS OF SOIL QUALITY Common name Scientific name Botanical family Soil type Helecho marranero Pteridium aquilinum Pteridiaceae (L)* Poor (Mashiu) “ “ (A) Mangaguasca Braccharis trinervis Compositae (L) Poor (Ma-shuuti) Philippia usambaresnsis Ericaceae (A) Escoba Lanosa Andropogon bicornis Gramineae (L) Poor (Digitaria) Digitaria sp. “ (A) Siempre Viva Commelina difusa Commelinaceae (L) Fertile (Olaiteteyai) Commelina africana “ (A) Papunga Bidens pilosa Compositae (L) Fertile (Enderepenyi) “ “ (A) Hierba de chivo Ageratum conyzoides Compositae (L) Fertile (Olmalive) “ “ (A) *(L = Latin America, A = Africa) Barrios et al., 2006 Geoderma
- 65. Soil food web structure - disturbance and recovery H. Ferris ,UC Davis
- 66. Effects of minor disturbance H. Ferris ,UC Davis
- 67. Effects of greater disturbance H. Ferris ,UC Davis
- 68. Effects of Stress H. Ferris ,UC Davis
- 69. CHALLENGE: Learning more about BGBD by looking at AGBD REMOTE SENSING Local Indicator Plants ‘Hotspots’ of soil Key Selected Selected biological activity Functional Soil Ecosystem Groups Processes Services Adapted from Barrios,2007 EcolEcon
- 70. 1. Degrading our Natural capital 2. Belowground biodiversity and function 3. Soil-based Ecosystem Services 4. Biological indicators of Soil Health 5. BGBD and Agroecosystem Management 6. Future Challenges
- 71. AGBD/BGBD Interactions Plant Biodiversity (AGBD) SOIL HETEROGENEITY (microniches) Belowground Biodiversity (BGBD) Is there a critical number of functional groups? Is the presence of certain species essential?
- 72. Identifying, Quantifying and Mapping Host Spots of Biological Activity and Ecosystem Services Temporal and spatial dynamics as a result of environmental factors in situ Predictive knowledge of Ecosystem Service Provision
- 73. Maintaining the right balance between Productivity and other Ecosystem Services PROD. ES
- 74. Developing Soil Health Monitoring Systems to evaluate Ecosystem Service provision performance Allow rural communities, environmental/agricultural institutions and local government Prepare for negotiations related to Payment for Ecosystem Services
- 75. PAYMENT FOR ECOSYSTEM SERVICES THANK YOU