The Role of Trees in Sustaining Soil Productivity in Sub Saharan Africa

Alex O. Awiti, PhD

World Agroforestry Centre (ICRAF) 29th July 2009

Trees   Can trees deliver on the global challenges of climate

change, water scarcity, food crisis, energy crisis and land degradation?

  Can trees be the straw that breaks the vicious “poverty traps” in sub Saharan Africa?

      The 21st Century Must be a green economy and trees

are the currency (Green Bucks)   But we must move beyond Trees and Soil Productivity;

Agroforestry has truly “Come of Age”

Yes trees can

What I hope to achieve

Next time you see a bumper sticker “Tree hugging dirt worshipper” you will know what they are going on about

19th Century: crisis of soil

  Thomas Malthus-On the

Principle of Population   Population growth would

outrun the growth of food production

  Worn out soils

  Capitalist agriculture as robbing the earth’s capital stock -separation of town and country-nutrient exports

  Response: from bones of the dead in Napoleonic battlefields to Peruvian guano

  van Liebig’s law of the minimum (mineral nutrient theory) in the 1840’s-

  Karl Marx’s penetrating insight of the effect of soil fertility decline on society –  Hunger and rural poverty

The triumph of the 20th Century

  Fertilizers   Pesticides   Irrigation   Steel ploughs/mechanical reapers   Hybrid seed

  On well watered soils mineral application catalyzed a quantum jump in global grain yields- from 1ton/ha (1900) to 3 ton/ha (2000) – North America and Europe 6-9 ton/ha.

The triumph of the 20th Century   A Green Revolution in Asia

–  India moved famine food self sufficiency in under a decade

  The Malthusian ghost was “finally slain” population now seemed to increase in an arithmetic ratio and food production in geometric ratio

  Environmental decline  Silent Spring

– Return to the “Dark Ages”. Insects and diseases and vermin would inherit the earth, millions would suffer from malnutrition and starve to death.

Limits to Growth

 A report by Meadows et al. to the Club of Rome in 1972 concluded that; – The limits to growth on the planet will be

reached in 100 yrs. Criticized as pessimistic and neo-Malthusian   The edifice of civilization had become

astonishingly complex, we lost our connection with the earth

The MEA (2005)   Changes being made in ecosystems are increasing

the likelihood of nonlinear changes in ecosystems with important consequences for human well-being.

  AR4 (2007) - Climate change is unequivocal. These changes are anthropogenic

  Lovelock’s Gaia hypothesis: complex interacting systems that maintains the climatic and biogeochemical conditions

End of Growth?

End of Growth

  Drier Murray-Darling Basin? Get used to it

  Net loss of 200 cubic km since 2001.

  Salinization

  Canadian Prairie-Back to a dusty future –  Due to melting mountain

glaciers rivers declined to 60%   Irrigation   Municipal use   Oil processing

  The Ogallala Aquifer: Can it be saved? –  Overdrawn at a rate of 3.1

trillion gallons a year –  Wells as deep as 1mile.

  The Bihar Plateau –  Irrigation-energy/fertilizer

response

The Challenges of the 21st Century   Global scale

–  Anthropogenic climate change

–  Water stress –  Energy –  Rapid population growth –  Land degradation –  Convergence of food, feed

fuel economies –  Biodiversity losses

  Sub Saharan Africa –  Poverty –  Hunger/Malnutrition –  Rapid population growth –  Deforestation/Land

degradation –  Vulnerability to climate

change –  Infectious Diseases/HIV/

AIDS –  Water stress /sanitation –  Energy –  Biodiversity loss –  Conflict

Sub Saharan Africa   Triple whammy in economic development

–  Dependency on declining biophysical asset base (soil, vegetation, water) productivity, rising hunger and poverty (exacerbated by climate change, water scarcity and amplified by emerging and re-emerging infectious diseases

–  Rapid population growth, youth bulge, declining per capita

land, unemployment, rapid urbanization –  Weak and inept state and private institutions, crippled by poor

infrastructure, low access to credit and markets. But strong non –state actors (social institutions)

  A coupling of social-ecological systems initiating ,driving and exacerbating a -veritable poverty trap

Sub Saharan Africa: Coupled human-ecological systems

Coupled Human and Ecological Systems

Can Trees break the “Poverty Trap” ?

Evidence-based tree solutions   We are good at matching

trees to biophysical parameters (Characterization, suitability)

–  Soils, rainfall, temperature

  We have not done a good job with matching trees to household, economic, institutional, ecosystem characteristics (matching trees to sites and systems)

  What are the socio-economic and biophysical determinants of adoption/non adoption of agroforestry technologies; Is adoption covariate or idiosyncratic?

  Linking trees (agroforestry) to products, goods and services beyond household to ecosystems to global level

Evidence-based Tree Solutions

Beyond Households and Livelihoods to Ecosystems and Global Sustainability

  Domestication, multiplication, cultivation and conservation of superior tree/shrub germplasm

  Developing and refining soil health diagnosis and targeting of agroforestry interventions to enhance livelihood and ecosystem services

–  Differential diagnosis   targeting agroforestry-determining “family-landscape tree enterprise

portfolio”

  Developing policies, incentives and institutional capacity for households, communities and governments to access funding/benefits for afforestation and improved forest management

Beyond Households and Livelihoods to Ecosystems and Global Sustainability

  Improving access to financing and marketing for tree products for smallholder farmers and identifying partnerships for product development and value addition

  Remote sensing, field measurement and modeling of carbon stock changes in forests and agricultural land –  Feasibility assessment for

REDD/AFOLU –  Baseline –  carbon stock inventory –  Monitoring carbon stocks

New Wine New Wine Skin

New Wine New Wine Skin

We have work to do

Thank You