Renewable Resources

1

• Renewable Resources
• Reading
• Perman et al (2nd ed.) Chapters 9 and 10
• Perman et al (3rd ed.) Chapters 17 and 18

2

• Renewable flow resources
• Such as solar wave wind and geothermal energy.
• These energy flow resources are non-depletable.
• But entail costs in harnessing them as usable
  energy resources

3

• Renewable stock resources
• living organisms fish cattle and forests with
  a natural capacity for growth
• inanimate systems (such as water and atmospheric
  systems) reproduced through time by physical or
  chemical processes
• arable and grazing lands as renewable resources
  reproduction by biological processes (such as the
  recycling of organic nutrients) and physical
  processes (irrigation exposure to wind etc.).
• Are capable of being fully exhausted.

4
Biological growth processes G G(S) An example
(simple) logistic growth Where g is the
intrinsic growth rate (birth rate minus mortality
rate) of the population.
5
Figure 17.2 Steady-state harvests.
6
Commercial fisheries Open access vs Restricted
access fisheries What is an open access
fishery Consequences of open access entry
continues until all rents are dissipated (profit
per boat zero). Stock sizes will tend to be
lower and harvest rates will tend to be higher
(but may not always be) compared with a
restricted access (private property or common
property) fishery. Exhaustion or even
extinction is more likely but will not
necessarily happen.
7
Switch now to Model Equations document
8
Figure 17.3 Steady state equilibrium fish
harvests and stocks at various effort levels.
9
Figure 17.4 Steady state equilibrium yield-effort
relationship.
10
Figure 17.5 Stock and effort dynamic paths for
the illustrative model.
11
Figure 17.6 Phase-plane analysis of stock and
effort dynamic paths for the illustrative model.
12
(No Transcript)
13
(No Transcript)
14
Figure 17.7 Present value maximising fish stocks
with and without dependence of costs on stock
size and for zero and positive interest rates.
15

• OPEN ACCESS AND SPECIES EXTINCTION
• The extinction of renewable resource stocks is a
  possibility in conditions of open access but
  open access does not necessarily result in
  extinction of species.
• Open access enhances the likelihood of
  catastrophic outcomes because
• Incentives to conserve stocks for the future
  are very weak.
• Free riding once a bargain has been struck
• Crowding diseconomy effects

16

• EXCESSIVE HARVESTING AND SPECIES EXTINCTION
• There are many reasons why human behaviour may
  cause population levels to fall dramatically or
  in extreme cases cause species extinction. These
  include
• Even under restricted private ownership it may
  be optimal to the owner to harvest a resource
  to extinction. Clark (1990) demonstrates
  however that this is highly improbable.
• Ignorance of or uncertainty about current and/or
  future conditions results in unintended collapse
  or extinction of the population.
• Shocks or disturbances to the system push
  populations below minimum threshold population
  survival levels.

17

• WHATEVER THE REGIME SPECIES EXTINCTION IS MORE
  LIKELY
• the higher is the market (gross) resource price
  of the resource
• the lower is the cost of harvesting a given
  quantity of the resource
• the more that market price rises as the catch
  costs rise or as harvest quantities fall
• the lower the natural growth rate of the stock
  and the lower the extent to which marginal
  extraction costs rise as the stock size
  diminishes
• the higher is the discount rate
• the larger is the critical minimum threshold
  population size relative to the maximum
  population size.

18

• Renewable resources policy
• Command-and-control
• Quantity restrictions on catches (EU Total
  Allowable Catches)
• Fishing season regulations
• Technical restrictions on the equipment used -
  for example restrictions on fishing gear mesh
  or net size or boat size.
• Incentive-based policies
• Restrictions on open access/property rights
• Fiscal incentives
• Establishment of forward or futures markets
• Marketable permits (individual transferable
  quotas ITQ)

19
Forestry As far as forests as sources of timber
are concerned much of the previous analysis
applies. But a new issue arises the average
length of a rotation. What is also important
here is the multiple service functions of much
forestry. This can often extend optimal rotation
lengths.