Delivering trees to farmers: improving strategies for germplasm supply

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Delivering trees to farmers improving strategies
for germplasm supply Session 2.3. Particular
issues for germplasm access, quality and
management at a smallholder farm level Tuesday
30 October 2007
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Introduction

• Particular features of smallholder agroforestry
  systems that are constraints on tree germplasm
  supply and quality
• Will consider tree spatial distributions and
  germplasm management practices by smallholders
• Why do we need to consider these issues? Since
  they need to be understood in order to develop
  appropriate interventions at a local level

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Introduction

• We are interested particularly in considering the
  implications of distributions and management
  practices for diversification in order to
  understand how to enable farmers to diversify
  their businesses and environment through planting
  a greater variety of trees of appropriate quality
• Will focus on example of work done in East Africa
  can consider if similar elsewhere

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Tree spatial distributions

• Farm tree inventories tell us that
• There are often many tree species in the farm
  landscape, but these often show very aggregated
  distributions. Sometimes aggregation can be at a
  community (between village) level
• There are many tree species in the farm landscape
  but most are at very low (sometimes extremely
  low) densities

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Tree spatial distributions

• In a recent survey in Kenya, more than 300 tree
  species were observed, but 75 of species had
  densities of less than one seeding tree per
  hectare. More than 50 of species, primarily
  indigenous, had a density of less than 0.25 trees
  per hectare
• The exception on low density is for a few
  dominant species. These are generally exotic,
  although, more rarely, can be indigenous.
  Sometimes these taxa dominate simply because
  germplasm of these is the most readily available

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Tree spatial distributions

• Some of the consequences are
• As farmers often must rely on on-farm sources for
  their germplasm (often the only sources currently
  available to them), low densities and aggregation
  lead to limited access to a diversity of species
  (and associated information) at an individual
  farmer level
• As densities are often very low, trees may not
  set seed (many species need a mate to breed
  with!)

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Tree spatial distributions

• The final result is
• It is difficult for farmers to plant a wider
  range of species to diversify their businesses,
  even if they would like to

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Germplasm management practices

• Nursery and farmer germplasm source surveys tell
  us that
• Once trees have become established on farms,
  farmers often rely on these for further supply of
  germplasm for subsequent planting rounds (one
  off introductions)
• When undertaking germplasm collection, farmers
  and nursery managers tend to collect from only a
  small number of trees

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Germplasm management practices

• In a recent survey in East Africa, seed to
  establish nursery lots was collected from an
  average of only 6 trees. In 22 of cases, seed to
  establish nursery populations was sampled from
  only a single tree

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Germplasm management practices

• Some of the consequences are
•  The genetic base of tree species in farm
  landscapes, which may already be low, will become
  increasingly narrow. This narrowing may result in
  productivity losses many tree species suffer
  from inbreeding depression, resulting in loss in
  growth, loss in fruit production, etc.
• A narrowing of genetic variation also results in
  a loss of adaptability to various pests/diseases,
  and an inability to respond to changing markets

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Germplasm management practices

• The final result is
• Farmers begin to experience lower productivity
  from the individual tree species that they
  cultivate. Ultimately, this may result in the
  loss of functionality, and hence value, of entire
  farm ecosystems

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Possible interventions at a local level

• How can we address the limitations imposed by
• Aggregation
• Low tree density
• Limited collection of mother trees
• Limited new introductions
• ?

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Exercise possible interventions at a local level

• What possible interventions can be applied to
  address these limitations?
• Table groups meet for discussion for 15 min
• Choose a reporter and very briefly discuss
  results in plenary two key interventions only