The role of resource economics in the control

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Resource Economics and invasive plants
The role of resource economics in the control of
invasive alien plants in South Africa
Author Jane Turpie
Turpie, J. (2004).The role of resource economics
in the control of invasive alien plants in South
Africa. S. Afr. Sci. 100, 87-93.
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The establishment of the WfW
General

• 8750 introduced species.
• Over 200 considered to be seriously invasive.
• By 1997, 180 woody plant species covered 10
  million hectares of land.

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The establishment of the WfW
The biomes effected

• The Fynbos biome is hardest hit.
• Grassland and Savanna biomes worst hit in the
  moister areas.
• Semi-arid Nama and Succulent Karoo biomes invaded
  by saltbushes, cacti, and mesquite trees.
• Extent of invasions in forests is unknown.

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The establishment of the WfW
Why established and successes

• Realisation of implications of invasive species
  for water supply.
• Placed it into an economic context.
• This led to the establishment of the WfW.
• Have cleared over 171 000 ha.
• Follow up weeding of 183 000 ha.
• 24 000 people employed in 2000.
• Spent over R3 billion.

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Economic worth of ecosystems
Ecological-economics

• In a strict sense the term biodiversity should
  include ecosystem functioning as well as species
  richness.
• Ecological-economics recognises the important
  role played by ecosystems in the economy.
• Ecosystems have both tangible and non-consumptive
  values.
• Tangible goods carry the most political weight.

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Economic worth of ecosystems
Direct-consumptive values

• Structural diversity and organisation of
  ecosystems must be maintained.
• This maintains the systems primary productivity,
  which in turn adds to its direct consumptive
  value.

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Economic worth of ecosystems
Non-consumptive values

• Include things like water purification and
  regulation as well as carbon sequestration.
• Genetic diversity and organisation also maintains
  ecosystems economic worth in terms of
  recreational value, option value, and existence
  value.

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Costs of alien plant invasions
Focus of studies

• Initial studies focused on the economic
  consequences of water loss.
• The scope then expanded to include losses
  incurred in tourism, natural resource harvest,
  pollination services, option value, and existence
  value.
• Recently studied have also included the effect of
  invasions on fires.

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Costs of alien plant invasions
Monetary costs of clearings

• It is very costly.
• Would cost about R650 million per year for the
  next 20 years.
• Not enough is being spent on it which simply
  amplifies the problem over time.
• In some areas the cost of clearing is easy to
  justify.
• Natural resources do not always have a high
  economic worth.
• Also varies with control method.
• Some alien invasives carry an economic worth.

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Costs of alien plant invasions
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Costs of alien plant invasions
Short-comings of previous studies

• The total cost of alien invasives has not been
  calculated due to differences in approaches used.
• Virtually all the studies have targeted riparian
  or terrestrial invaders.
• Studies have also varied in terms of the types of
  impacts assessed.
• Secondary effects of alien invaders have not been
  analysed.
• What about changing demands?

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The valuation of water losses
Two methods

• Two methods used to value water losses,
  replacement costs and opportunity costs.
• Alien invasions can actually lead to the
  breakdown of the entire ecosystem.

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Other effects of alien invasions
Effects other than on water loss

• The easiest to estimate are impacts on direct
  consumptive values.
• Recreational value of biodiversity usually
  measured using the travel-cost method.
• No studies have looked at effects of alien
  vegetation on biodiversity as a whole.
• The effects of fire have been well researched.
• The deleterious effects of fire are increased
  with invasions.
• Fynbos is also important for commercial fruit
  orchards as well as the local honey industry.

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Other options
Two available options

• The other options available are regulatory and
  incentive methods.
• Regulatory methods have been shown to be
  ineffective as well as not socially optimal.
• Incentives will therefore be the best.