ecoModule1 by 2jEJEK


									Economic Analysis of
Invasive Species

                 Module 1:
    about invasive species
what this module covers
1. Understanding
   invasive species - a   about                         Module 1
                          invasive species
   biological and
   development issue      economic analysis of
                                                        Module 2
                          invasive species
2. Movement and
   introduction of        impacts of invasive species
                                                        Module 3
   invasive species       and ways to address them

3. Types of organisms     defining invasive-related
                                                        Module 4
   that can become        costs & benefits
   invasive               valuing
                                                        Module 5
4. Linking invasions to   ecosystem impacts
   other environmental    informing actions
   pressures              to address invasives
                                                        Module 6
What are alien invasive species?

 and why do we care about them enough
  to have a training course on invasive
  species for economists??
   Some definitions:
   An alien species is a species that has been
    introduced to a location (ecosystem or
    area) where it does not occur naturally
   An alien invasive species (IAS) is an alien
    species that causes (or has the potential
    to cause) harm to the environment,
    economies and/or human health
Can you have an invasive species that is not alien??
The change in status from a native species in a stable ecosystem to an
invasive species is always accompanied by some change that makes the
invading species “different” or “alien” – mostly by being introduced, but
sometimes because the ecosystem itself changes
Thus we sometimes use the term “invasive species” (IS)
Invasions by Alien Species
 Steps in the progression to invasion:
 1. Introduction – intentional or unintentional
 2. Establishment – survives but doesn’t spread
 3. Spread:
 3a. Naturalisation – becomes part of the
   flora/fauna of its new habitat
 3b. Invasion – expands and impacts on species
   and ecosystems and people and development

 Probability = 10% (2) x 10% (3a) x 10% (3b) = 0.1%
 i.e. only 1 in 1000 introduced species ever become
    invasive – usually less, some say 1 in 1,000,000
Introductions are mostly due to
 human activity and can/may
    result in establishment
  “Intentional                         “Unintentional
    Introduction”                       Introduction”

    For food, agriculture, forestry,     Species that move with
    horticulture, decoration, etc.,      other imports
A plant or animal enters a new environment or
  habitat or country and survives in the wild –
  without human help (such as horticulture,
  aquaculture, aquarium support or
e.g. Many “low-level weeds” and accidentally
  introduced invertebrates

 Ornamental canna established   Wild canna established
The established animal or plant
 starts to reproduce without
 assistance and the young
 survive and begin to spread
                                  European birds
                                   naturalised in
South American                       Australia
Senna spectabilis
in Africa begin to
after decades or
centuries of
Wild canna (Canna indica)
naturalised as a weed and
spreading in Eastern Africa

   Naturalisation can be equated with “escape from human care”

The established and
  naturalised species
  spreads and “gets out of
  hand”, competing with         Australian possums
                                   invaded NZ
  native (and other
  established) species,
Impacting ecosystems and
  causing environmental
  damage and/or impacts
  on human welfare and        Latin American Green
  development                Apple Snail invaded Asia
1. Introduction
2. Establishment
3a.Spread - Naturalisation

     The House Sparrow
        spreading and
      invading Tanzania
        over 90 years
Steps to invasion:
Once introduction, establishment and
  naturalisation have occurred there is
  often a “lag time” before further spread
  and invasion
In some species (e.g. trees) this may be
  more than 100 years, in others (e.g.
  water hyacinth) it may be a few weeks
As the invading species consolidates, so
  its affected plant or animal habitats
  decline or become degraded
Habitat occupation changes
      during invasion

Introduction                     Invasion      Consolidation

                 Process of Invasion from
               Introduction to Consolidation
                      (after Williams, 2003)
Invasions can thus be
stopped at several stages:
• Best is prevention = stopping introductions
• Next best is eradication = destroying or
  removing a new invasion
• Third is containment = stopping a new
  invasion from further spreading
• Last (and most expensive and time-
  consuming) is management of established
  invasions + restoration of affected systems
   We will discuss these options in Module 3
Movement and Introduction
   of Invasive Species
Vectors: means by which invasives species are moved
cars, trucks, buses, aircraft, boats, ships,
people, clothes, suitcases, boxes, containers ..

    There are six million steel containers moving around the world at any one time

        »» and: flowing water, tides, storms, floods, winds….
Movement of Invasive Species
 Pathways: routes along which invasive species are
   moved or move themselves
 • roads, railways, air corridors, shipping lanes,
   travel routes, trade routes, migration routes,
   rivers, ocean currents, …

 Causes of the movement of invasive species
 • “The 4 T”s: Trade, Travel, Transport, Tourism
 • All of these have increased many thousand
   times in the last century due to increasing
   globalisation– thus spreading species around
   the world and facilitating their introduction to
   “new” countries and areas where they are alien
   Shipping routes now reach every continent (even
Antarctica) and air travel reaches most cities in the world
Introduction of species
 The movement (by human action) of a species outside its
  native range can result in introduction. This movement
   can be either within or between political boundaries

      Some establish,                     Some establish,
       naturalise and                      naturalise and
          spread                              spread
Invasive taxa (types)
• Invasive species can animals, plants or
  micro-organisms (including those causing
  disease in plants, animals and people)
• They can be terrestrial, aquatic or marine
• They can be pathogens, parasites or
• They can be minute, small, large – as well as
  widespread or locally abundant

  Some examples from Eastern and Southern
               Africa follow:
• Micro-organisms such as:
Plant and animal viruses, bacteria, yeasts,
Fungal pathogens of both animals and

• Invertebrates such as:
Molluscs (both terrestrial and aquatic)
Insect pests
Other arthropods …………
Argentine Ant
spreading in SA
                                Greater Grain borer from Southern
                                      USA now widespread

                   tree borer
                    in many
                                   Louisiana Crayfish
                                   spreading across Eastern
                                   and Southern Africa
Vertebrate invasive species include:
fish, reptiles, birds and mammals

 Nile tilapia was intentionally
 introduced to many water
 systems in Africa, Asia and Latin
 America – with devastating

  Common carp from China
  is now invasive in
  waterbodies on four
  continents including Africa
  Lantana camara is a classic IAS which
 (after 160 years) is still spreading across
Africa and invading new lands - as well as
  in Australia, Asia and North America

                                               Lantana replaces
                                               native vegetation
                                                and pasture, is
                                                 poisonous to
                                                 livestock and
                                               harbours tsestse
                                                 flies and rats
Prosopis (spp.), Mesquite, from
Central America. An alien invasive
introduced for agrofrestry, grows
well in dry (pastoral) areas

    Causes wounds with its spines, replaces native dryland
   vegetation and destroys pastures for livestock and wildlife
  “Invasiveness” of
   Alien Species
What makes a good invader?
•Rapid growth rate
•Great dispersal characteristics
•Large reproductive capacity
•Broad environmental tolerance
                                           Lianes in Seychelles
•Effective competitor with local species
           All invasive plants can be called “weeds”
            BUT: Not all weeds are invasive species
   Finally: Invasives and
   climate change
Climate change is upon us - although not
  exactly predictable in area or extent
Climate change will make ecosystems more
  vulnerable to invasions
Invasive species are already “taking
  advantage” of changed climatic conditions
  and expanding to the detriment of local
  species, habitats and ecosystems
Thus we must be prepared for ecosystems
  affected by climate change to be further
  invaded and we must develop tools to
  predict and prevent these extra invasions

To top