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Can agroforestry increase reliability of subsistence agriculture under future climate in southern Africa? Amber Kerr Ph.D. Qualifying Examination Energy and Resources Group November 16, 2007 Talk outline 1. Motivation and background - Climate change and agroforestry Why is southern Africa a good case study? 2. Agroforestry systems in southern Africa 3. Research task 1: Field work in Malawi & Zambia - Potential field sites Hypotheses, plot design, and manipulations Metrics, statistics, possible results 4. Research task 2: Proxy data and modeling 5. Next steps and long-term plan 1 of 38 1. Motivation and background 2 of 38 Climate change in the developing world “Poorer, developing countries are the least equipped to adapt to the potential effects of climate change, although most of them have played an insignificant role in causing it; African countries are amongst the poorest.” ~ Pak Sum Low, Climate Change and Africa, 2005 “The international community must urgently scale up its support to climate-proof the farming systems of the poor, particularly in Sub-Saharan Africa.” ~ World Bank, World Development Report 2008 3 of 38 Predicted changes in T and precip, 2080-2099 QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Assemblage of 21 climate models using the A1B scenario. (From Figure 11.2 in IPCC AR4 WG1, 2007). 4 of 38 Southern Africa’s vulnerability “Assessments of water availability, including water stress and water drainage, show that parts of southern Africa are highly vulnerable... Food security, already a humanitarian crisis in the region, is likely to be further aggravated by climate variability and change.” ~ IPCC AR4 WG 2, Chapter 9, “Africa,” 2007. “Climate change poses a serious threat to ecosystems and human well-being in southern Africa, both in the medium- and long-term... Warming and drying at the regional scale will have serious consequences for agricultural production.” ~ Southern African Millennium Ecosystem Assessment, 2004 5 of 38 Central question Which systems are most flexible on a short time Which scale? Are trees better intercrops than annuals? What biophysical mechanisms are important? agroforestry systems will maximize reliability of subsistence agriculture under southern Africa’s likely future climate? What can these systems tell us about agricultural climate adaptation in general? What is their sensitivity to changes in climate? Are these systems economically, culturally, and biologically appropriate for widespread adoption? 6 of 38 Vine support Homegardens Alley cropping Malagasy tavy Pigs grazing, Spain Cuban conuco Swidden Effet de vent, Monet, 1891 Leucaena and maize Vanilla in Réunion Examples of agroforestry Dehesa Windbreaks 7 of 38 Taungya Sugarcane, Australia Living fences Parklands Shade plantations Baobab, Senegal Shea & cassava, Uganda Costa Rica, sp. unknown Riparian buffers Beehive, Ethiopia Coffee, Columbia Mahogany & maize, Indonesia More examples of agroforestry Insect husbandry 8 of 38 The intellectual appeal of agroforestry: Using principles of ecology and economics to design complex (multispecies) agricultural systems that are efficient in their resource use, profitable, reliable, and sustainable. The practical appeal of agroforestry: Harnessing the power of different species combinations to allow farmers to achieve the greatest benefit from their limited resources. 9 of 38 Special challenges of agroforestry The same complexity that can make agroforestry systems more efficient can also make them: • Harder to design and model • More time-consuming to establish • A slower return on investment • More difficult to harvest a dna ™emiTkciuQ rosserpmoced )desserpmocnU( F FIT .erutcip siht ees ot dedeen era • More knowledge-intensive • More labor-intensive • More exacting in implementation Biophysical advantage alone is not enough to spur adoption of an agroforestry technology. 10 of 38 What does agroforestry have to do with climate change? Verchot et al. propose that “agroforestry... has a role to play in helping smallholder farmers adapt to climate change.” They suggest that trees in the agroecosystem may help buffer against both production risk and income risk. However: “Questions about the adaptation potential of agroforestry systems are very important and poorly studied. There is a great need for studies that are specifically designed to address this question.” ~ L. Verchot, pers. comm., 2/26/2007 Verchot, L.V.; M. van Noordwijk; S. Kandji; T. Tomich; C. Ong; A. Albrecht; J. Mackensen; C. Bantilan; and C. Palm. (2007). “Climate change: linking adaptation and mitigation 11 of 38 through agroforestry.” Mitigation and Adaptation Strategies for Global Change 12(5): 901-918. How agroforestry could contribute to climate adaptation • Improve microclimate – Shade reduce temperatures – Reduce wind speed reduce evapotranspiration • Improve soil quality – More soil carbon greater water-holding capacity – Nitrogen fixation reduce multiple stresses • Access alternate resources – More efficient interception of rainfall; less runoff – Hydraulic lift: bring water to surface from depth – Nutrient pumps: access nutrients at depth • Provide stable income source 12 of 38 How agroforestry could hinder climate adaptation • Tree-crop water competition – Reduces crop yield, and/or – Inhibits tree growth, reducing tree benefits • Lower rates of seedling germination and establishment – Reduces returns to labor • Loss of trees as a long-term investment – Tree death due to water or temperature stress – Abandonment of trees due to temporary or permanent migration 13 of 38 2. Agroforestry in Southern Africa QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. 14 of 38 Why is southern Africa a good region to study climate change and agroforestry? • Much experience in agroforestry over past several decades; established research centers and extension networks • Existing needs are considerable (e.g. food security, income generation) • Climate change impacts expected to be severe (though the region’s contribution to climate change has been negligible) • Climate variability is an ongoing problem even in the absence of climate change 15 of 38 Agriculture in southern Africa • Maize is the staple crop (~80% of calories), supplemented by legumes and tubers • Soil fertility inherently low, and diminishing; N limitation widespread • Rainfall erratic; droughts and floods common • Farm sizes very small (most are 0.2 - 2 ha) • Most farmers cannot afford fertilizer or other external inputs. • Farmers engage in local cash transactions, but infrastructure limits access to broader markets. 16 of 38 Improved fallows Year 1 Year 4 Year 2 Year 3 (In some systems, it is possible to grow three or more continuous years of maize without a decline in yields, but two years is more common.) 17 of 38 Relay intercropping November September January July March May 18 of 38 Hedgerow intercropping November September January July March May 19 of 38 Intercropping in Zambia Photo: ICRAF 20 of 38 Southern Africa agroforestry legumes Leucaena leucocephala Gliricidia sepium Sesbania sesban Tephrosia vogelii These species are often 21 of 38 trained as hedgerows. Cajanus cajan 3. Proposed fieldwork QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. 22 of 38 Four questions As climate change is imposed upon southern Africa’s agroforestry systems, Q1: Will these systems still confer yield benefits? Q2: Will any one system design outperform the others? Q3: Will tree-crop water competition increase? Q4: Will establishment success of seedlings decrease? Outcomes Mechanisms 23 of 38 Experimental manipulations • Factors that could affect agroforestry include: – – – – Increased average and maximum temperature Decreased rainfall Fewer and later rainfall events Elevated CO2 • Ideal to manipulate all of these over years to look for long-term and interaction effects. • However, due to limited time and resources, I have chosen to focus on rainfall manipulations. • Rainfall may be the factor with the greatest effect on agricultural production in this region. 24 of 38 Rainout shelters Gutters to intercept and remove rainfall Buffer zone (control for edge effects, roots, etc.) Sampled subplot (usually ~0.5 of total area) Reduction in rainfall should be proportional to area covered (in this picture, ~30%) Rain gauges to ensure desired decrease occurs 25 of 38 Treatments and controls • Treatment 1: Improved fallows • Treatment 2: Relay intercrop • Treatment 3: Hedgerow intercrop • Control 3: Unfertilized maize • Control 2: Fertilized maize • Control 1: Annual legume Each of these treatments will be subjected to ambient and reduced (-30%) precipitation. I intend at least 5 replicates per treatment. 26 of 38 Plot design 90 cm between rows 90 cm within rows M = maize T = tree (absent in controls) Whole plot: 9 x 9 grid, (7.2 m)2, 81 indivs per species M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T Furrow M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T M T Ridge M T M T M T M T M T M T M T M T M T Sampled subplot: 5 x 6 grid, (4 m)2, 30 indivs per species 27 of 38 Data to collect • Grain yield • Tree biomass What happened? • Temperature and precipitation • Evapotranspiration • Soil moisture • Soil nutrients and soil carbon • Below-ground biomass Why did it happen? • Rooting profile • Germination and establishment 28 of 38 Proposed field sites Msekera Research Station, near Chipata, Zambia Makoka Research Station, 29 of 38 Thondwe, Malawi 4. Proxy data and modeling QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. 30 of 38 Proxy data: Interannual variability • There is an abundance of multi-year yield data for various agroforestry systems under ambient precipitation. • With these existing data, I will attempt a meta- analysis using interannual variability as a proxy for the effect of rainfall on the productivity of agroforestry technologies. • Another useful question might be to compare the water-use efficiency of agroforestry systems with monocultures in dry and wet years. 31 of 38 WaNuLCAS Water, Nutrient and Light Capture in Agroforestry Systems QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. WaNuLCAS is a multi-species crop model that simulates aboveand belowground plant architecture, competitive interactions, and environmental parameters. Image: Figure 1.2 in WaNuLCAS manual, v. 3.0 (van Noordwijk et al., 2005). Citation: van Noordwijk, M. and B. Lusiana (1999). “WaNuLCAS, a model of water, nutrient and light capture in agroforestry systems.” Agroforestry Systems 43: 217-242. 32 of 38 Modeling goals • Work on extending WaNuLCAS to include – effects of extended drought – effects on phenology • Identify and improve other aspects of the model that need to be modified to realistically simulate long-term climate change • Use empirical data (from fieldwork, and from interannual variability) to extend the model • Carry out simulations for fertilizer trees in Southern Africa: under what conditions and locations will these systems remain viable? 33 of 38 Uapaca kirkiana, wild loquat 6. Next steps and long-term plan 34 of 38 Next steps • Finish initial climate change simulations with WaNuLCAS (December 2007) and submit to Agroforestry Systems (February 2008) • Write first chapter of dissertation, reviewing relevant work, and draft second chapter analyzing proxy data (Spring 2008) • Apply for grants and fellowships: Rocca (February 2008), Switzer (February 2008), Lindbergh (June 2008), Fulbright-Hays (11/08) • Use ERG block grant funds for a preliminary fieldwork trip (Spring/Summer 2008) 35 of 38 Timeline 2008 2009 Fieldwork scoping trip QE First field season 2010 Second field season Modeling and Greenhouse proxy work work (optional) Lit review; initial modeling 2011 Data analysis Dissertation writing 36 of 38 Dissertation chapters 1. Introduction: Unanswered questions on agroforestry and climate change 2. A meta-analysis of agroforestry performance under current climate variability 3. Methods for fieldwork 4. Results from fieldwork 5. Modifications to, and results from, WaNuLCAS 6. Synthesis of experimental, proxy, and modeling results 7. Policy implications; future work needed 37 of 38 Acknowledgements I am grateful for the generous advice and support I have received from: My committee members: Margaret Torn, Dan Kammen, Lynn Huntsinger, Todd Dawson, and Carol Shennan. Other faculty members: John Harte, Louise Fortmann, Isha Ray. Researchers: Louis Verchot, Meine van Noordwijk, Jayant Sathaye, Asmeret Berhe. Graduate students: Adam Smith, Barbara Haya, Rob Bailis, Naïm Dargouth, Tracey Osborne, Dorothy Sirrine, Malini Ranganathan, Mike Kiparsky, Eric Hallstein, Teresa Chuang, Erin Conlisk, Danielle Svehla, Abby Swann, Michal Shuldman. ERG staff: Bette Evans and Donna Bridges. Friends, family and others: Kay Kerr, Rex Kerr, Jeremy Manson, April Kerr, Carol Childs, Zachary Mason, Hal Hatch. 38 of 38 Dicrurus adsimilis, drongo Auxiliary slides follow! 39 of 38 Goals of my dissertation work • To contribute to the resilience and prosperity of • • • • • smallholder agriculture. To elucidate mechanisms of interspecific resource competition in mixed annual/perennial systems. To further the development of agroforestry simulation models. To provide a case study on climate change adaptation in the agricultural sector. To gain experience with ecological methods, and with fieldwork in developing countries. To prepare for a career in research and teaching. 40 of 38 Not goals of my dissertation work • Economic, anthropological, sociological, or political analyses of agroforestry use and adoption. • An integrated assessment of climate change risks and adaptation options. • Agroforestry for climate mitigation (i.e. carbon sequestration). • Land surface modeling using remote sensing data. These topics are all very interesting, worthwhile, and relevant! But to keep the scope of this project realistic, I intend to become familiar with them only to the extent that they are necessary to answer my central question. 41 of 38 Predicted changes in soil moisture, 2080 - 2099 QuickTime™ and a ompressed) decomp ded to see thi s pictu (annual averages) Assemblage of 21QuickTime™ and a TIFF (Uncompressed) decompressor climate models using are needed to see thi s picture. the A1B scenario. (From Figure 10.12 in IPCC AR4 WG1, 2007). Black dots indicate lack of data. 42 of 38 Change in agricultural output, 2070-2099 Assuming CO2 fertilization effect QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. % change from present Assuming no CO2 fertilization effect From Cline, William (2007), Global Warming: Impact Estimates by Country. Assumes some adaptation and SRES A2 scenario. 43 of 38 Human population density and NDVI Where do people live who might be most affected by climate change? 44 of 38 Agroforestry defined The art and science of growing woody and nonwoody plants together on the same unit of land for a range of benefits. - Huxley, 1999 All practices that involve a close association of trees or shrubs with crops, animals, and/or pasture. - Rocheleau et al., 1988 An old and widely practiced land use system in which trees are combined spatially and/or temporally with agricultural crops and/or animals. - Farrell and Altieri, 1995 Agroforestry is an indistinct concept within a broader agroecological context... [it] defies precise definition. - Wojtkowski, 1998 45 of 38 Central agroforestry hypothesis The trees must acquire resources that the crop would not otherwise acquire. increase in crop yield (goal is to be >0) I = F-C competitive effect of trees fertility effect of trees or, more specifically, I = Fnoncomp - Ccomp,nonrecycled non-competitive fertility effect of trees (resources that would not otherwise be acquired) competitive non-recycled effect of trees (resources taken from crop and not returned) Cannell, M. G. R.; M. van Noordwijk and C. K. Ong (1996). “The central agroforestry hypothesis: the trees must acquire resources that the crop would not otherwise acquire.” Agroforestry Systems 33: 1-5. 46 of 38 Agroforestry as ecosystem mimicry In theory, agroforestry systems can confer some of the benefits of natural ecosystems by mimicking their structure and function. For example: • Complementarity of resource use may make polycultures more productive than monocultures. • Biodiversity may increase resistance to disease. • The physical environment may favor functional traits not usually found in food crops (e.g. perennial habit, deep-rootedness, deciduousness). Ecosystem mimicry remains a relatively unexplored concept! 47 of 38 Diversity, stability, and covariance • In theory, the yield variance of a multispecies system will not exceed the variance of a single-species system. Cassava Maize • If two species have a perfectly negative covariance ( = -1), in theory, the system variance can go to zero. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. From van Noordwijk, M. and C. K. Ong (1999). “Can the ecosystem mimic hypotheses be applied to farms in African savannahs?” Agroforestry Systems 45(1-3): 131-158. 48 of 38 In summary, agroforestry is... • A set of land-use systems with potential to enhance the economic and ecological viability of agriculture. • Not a panacaea. The wrong system in the wrong place can be disastrous. The right system in the right place can bring tremendous benefits to smallholders. 49 of 38 Failure of hedgerow intercropping Calliandra and maize, Katuk-Odeyo, Western Kenya, August 2004. 50 of 38 Unimodal precipitation regimes Summer maize planted Winter maize harvested QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. From Chirwa, P.W.; C.R. Black; C.K. Ong; and J. Maghembe (2006). “Nitrogen dynamics in cropping systems in southern Malawi containing Gliricidia sepium, pigeonpea and maize.” Agroforestry Systems 67: 93 - 106. 51 of 38 Agroforestry interventions • Could agroforestry provide solutions to some of southern Africa’s agricultural constraints? • ICRAF has been active in the region since the mid-1980s, and several national governments actively support agroforestry research. • Adoption is increasing but not yet widespread. • Three of the most widely tested systems are: – Improved fallows – Relay intercropping – Hedgerow intercropping Main goal: Improve maize yields through enhanced soil fertility. 52 of 38 Two slightly different questions: • Will agroforestry still provide benefits under future climate? • Will agroforestry be more or less useful under future climate than under current climate? My data should allow me to investigate both of these questions. 53 of 38 What does it mean to “increase climate resilience”? Under adverse climate conditions, would a resilient agricultural system have... • Less variability in yield? • Higher average yield? • Higher minimum yield? I will investigate these three metrics. • Faster recovery after a bad year? Agroforestry trees may also produce minor food crops or valuable non-food products; it is difficult to compare these directly with maize yield. 54 of 38 Unintended effects of rainout shelters • Reduced insolation • Reduced wind speed • Increased air temperature • Changed precipitation chemistry For these reasons, it will be important to include equipment control plots: plots over which similar, but non-rain-capturing, structures are placed. from Sala, O. E.; R. B. Jackson; H. A. Mooney and R. W. Howarth, eds. (2000). Methods in Ecosystem Science. New York: Springer-Verlag. 55 of 38 Improved fallows: methodological dilemma I would like to perform climate manipulations on improved fallows, but they require a four-year minimum to complete a cycle. What should I do? • Do two years of manipulations on each stage? • Manipulate only years 1 and 2 (tree establishment) and measure the biophysical changes? • Compmletely omit this system from the experimental design? 56 of 38 Fieldwork: open questions • If only using one species, what inferences can • • • • be made about cropping system? What conclusions could be drawn about 4-year improved fallows with only two years of data? Will the rainout shelters be effective and affordable? What is the best way to quantify the degree of tree-crop water competition? What would happen if there is significantly above-average rainfall for both years of the experiment? 57 of 38 Simulating climate change with WaNuLCAS “If you want to use a specific time-series of local climate change on the model, it will allow you technically to do so, but processes of tree mortality under prolonged drought are not included or tested yet. “Also, in an agroforestry context we think that tree phenology (flowering/fruiting) may be particularly responsive to climate change, and this aspect will definitely need more attention before the model will give anywhere near realistic results.” ~ Meine van Noordwijk, pers. comm., 9/29/07 58 of 38 Image credits Title slide: Acacia albida growing with sorghum and maize. Drawing by Terry Hirst from Agroforestry in Dryland Africa, D. Rocheleau et al., ICRAF, 1988. Motivation: www.metoffice.gov.uk/research/hadleycentre Developing world: from www.dkrz.de; see tinyurl.com/24zycc. Appeal of agroforestry: Rainforest: A.M. Stacey; tinyurl.com/39eqot Maize: Mrs Banda in Malawi; from ICRAF’s Image Database 59 of 38 Image credits, continued (2) Types of agroforestry systems: Dehesa: www.ibergour.com/images/dehesa_extremena.jpg Vine support: from Vanilla planifolia on en.wikipedia.org Windbreaks: Poplars - Wind Effect by Monet; worldmasterpieces.jp Swidden: photos.wildmadagascar.org/Deforestation.html Alley cropping: from ICRAF, via Cornell Hort 400 webpage Homegarden: www.bioversityinternational.org (publication 753) Parkland (shea): www.fao.org/docrep/008/y5918f/y5918f11.htm Parkland (baobab): edcintl.cr.usgs.gov/senegal2/sine.html Living fence: Emma Young, tripsource.com. Use by permission. Riparian buffer: davidwallphoto.com/searchresults.asp?g=85 Taungya: www.fao.org/docrep/008/af335e/af335e03.htm Coffee: Café Mesa de los Santos from www.new-ventures.org Beehive: www.bridgebie.org/Village Farm/Village Farm.html Dead acacia: www.wanderingnomads.com/gallery/bw13.jpg 60 of 38 Image credits, continued (3) Africa political map: www.mongabay.com/images/african.gif Africa population and NDVI: CIESIN and NASA. Southern Africa title: from CTA (2002), “Agroforestry in Malawi and Zambia: summary report of a CTA/MAFE study visit.” Southern Africa agroforestry species: Sesbania: www.css.cornell.edu/ecf3/Web/new/AF Cajanus: vinehillcashmere.bigblog.com.au Tephrosia: mybirds.ru/groups/popug/tephrosia.jpg Leucaena: from forum.ctu.edu.vn; see tinyurl.com/3xgpcp Leucaena hedgerow: instruct1.cit.cornell.edu/courses/hort400/ Gliricidia: accesscom.com/~jfinger/trees/ Field work title: Photo by the author. Graphic from van Noordwijk, M. (1999). “Scale effects in crop-fallow rotations.” Agroforestry Systems 47: 239 - 251. Zambia and Malawi maps: World Book Multimedia Encyclopedia, 2004 Edition, version 8.2.1. 61 of 38 Image credits, continued (4) Conclusions: www.vumba-nature.com/habitat-woodlands.htm Drongo: commons.wikimedia.org Guava: www.ilivetocook.com/images/cooking/guava.jpg Quoll (photo and caption): www.epa.qld.gov.au, Bulletin, 9 Nov 04 62 of 38 5. Relevance to theory and policy 63 of 38 Change in global agricultural output (1) QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. From Cline, William (2007), Global Warming: Impact Estimates by Country. Washington, DC: Center for Global Development. Assumes some adaptation and SRES A2 scenario. These data assume a CO2 fertilization effect. 64 of 38 Change in global agricultural output (2) QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. From Cline, William (2007), Global Warming: Impact Estimates by Country. Washington, DC: Center for Global Development. Assumes some adaptation and SRES A2 scenario. These data assume no CO2 fertilization effect. 65 of 38 Building blocks of agroforestry Loose Stable 66 of 38 Quolls must be passed with care Ranger Martin Fingland with a juvenile spotted-tailed quoll. Photo by Anthony Weate, courtesy of The Courier-Mail. 67 of 38