Module 1:

what decision-makers need to know about

invasive species

Developing legal and institutional frameworks

for invasive alien species

what decision-makers need to know about invasive alien species2

what this module covers

1. what ‘invasive alien species’ and ‘invasion’ means

2. pathways for species introductions

3. impacts of IAS

4. problems of prediction and links to other environmental pressures

5. the importance of information and available international resources

what decision-makers need to know about invasive

species

what decision-makers need to know about invasive

species Module 1Module 1

laying the foundations for effective national frameworks

laying the foundations for effective national frameworksModule 2Module 2

preventing biological invasions

preventing biological invasions Module 3Module 3

responding to biological invasions

responding to biological invasions Module 4Module 4

getting results: compliance, enforcement and liability

getting results: compliance, enforcement and liability Module 5Module 5

legal frameworks for cooperation beyond borders

legal frameworks for cooperation beyond borders Module 6Module 6

many different terms – a complex area

what are invasive alien species?

an alien species is a species that has been introduced to a location (ecosystem or area) where it does not occur naturally

an invasive alien species (IAS) is an alien species that causes (or has the potential to cause) harm to the environment, economies and/or human health

introductions are nothing new...

...but globalisation has led to massive expansion of opportunities for introductions

what type of species invade?

from all taxonomic groups

• vertebrates (e.g. mammals, fish, birds, reptiles)

• invertebrates (e.g. insects, snails, worms)

• aquatic, marine and terrestrial plants (e.g. weeds, trees)

• micro-organisms (e.g. viruses, bacteria)

Process of Invasion

2. Establishment

3. Spread

1. Introduction– intentional or unintentional

– survives but doesn’t spread

(a) naturalisation – becomes part of new habitat’s flora/fauna

(b) invasion – expands and impacts on species, ecosystems people and development

1. Introduction

2. Establishment

3a.Spread - Naturalisation

3b. SPREAD - INVASION

the House Sparrow spreading and invading Tanzania over 90 years

Many IAS undergo a lag phase after initial establishment, and may remain unobtrusive before becoming invasive and spreading rapidly

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

Pop

ulat

ion

size

Time

Carrying capacity

Lag phase

Process of Invasion from Introduction to Consolidation

(after Williams, 2003)

Introduction Invasion Consolidation

habitat occupation changes during invasion

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

• Sequence endorsed under Convention on Biological Diversity

how do species get moved around?

Vectors – The specific mechanism by which a species is moved along a pathway (clothing, vehicle, boat hulls, ballast water, packaging, soil around plant roots...)

e.g. a tourist carrying seeds is a vector in the pathway of international airline flights

Pathways – The routes along which a species is moved or moves itself (roads, railways, air corridors, shipping lanes, rivers) ... including trade itself

Shipping routes now reach every continent (even Antarctica) and air travel reaches most cities in the world

ballast water

• a major vector for unintentional introductions in the shipping pathway

• up to 14 billion tonnes of ballast water transported around the world each year

• an estimated 7 000 – 10 000 species may be present in ballast water at any given time

Zebra mussels were introduced to the Great Lakes of North America in ballast water in the 1980s, and now cause severe economic impacts

introductionintroduction

establishmentestablishment

spreadspread

naturalisationnaturalisation

invasioninvasion

direct & indirect causes of introductions

direct causes

introduction of species for commercial purposes

e.g. aquaculture, seeds, crops, livestock, food, biofuels

introduction of species for commercial purposes

e.g. aquaculture, seeds, crops, livestock, food, biofuels

introduction of species for control purposes

e.g. biocontrol, landscape restoration

introduction of species for control purposes

e.g. biocontrol, landscape restoration

introduction of species for lifestyle and aesthetic

purposese.g. pets, ornamental plants, aquariums

introduction of species for lifestyle and aesthetic

purposese.g. pets, ornamental plants, aquariums

unintentional or accidental introductions

e.g. contaminated imports, hitch-hikers in freight or luggage, ballast water,

dumping

unintentional or accidental introductions

e.g. contaminated imports, hitch-hikers in freight or luggage, ballast water,

dumping

indirect economic causes

forces and conditions which determine trade, production and

consumption practices and

preferences e.g. expanding travel & trade, globalisation,

subsidies to production, trade and investment incentives, market demand and

consumer preferences, low fines, high reliance of economy on imports

forces and conditions which determine trade, production and

consumption practices and

preferences e.g. expanding travel & trade, globalisation,

subsidies to production, trade and investment incentives, market demand and

consumer preferences, low fines, high reliance of economy on imports

forces and conditions which determine land and resource

use practices and preferences e.g. high reliance of economy on particular

productions sectors, incentives to clear land and replace native species, price support to exotic monocrops, unclear institutions and property rights, lack of budgets and funding to conservation

forces and conditions which determine land and resource

use practices and preferences e.g. high reliance of economy on particular

productions sectors, incentives to clear land and replace native species, price support to exotic monocrops, unclear institutions and property rights, lack of budgets and funding to conservation

introduction of species

Some establish, naturalise and

spread

Movement by human action of a species outside its native range can result in introduction (into/within a country)

Some establish, naturalise and

spread

intentional introduction

unintentional introduction

for food, agriculture, forestry, horticulture, fisheries, hunting, ornamental and for pleasure ...

species that move with other imports as ‘hitchhikers’ or ‘stowaways’

impacts of IAS

negative impacts on:

• ecosystems

• economies

• human health

ecological impacts

• direct predation/herbivory

• competition for resources/exclusion (e.g. light, food)

• transmission of pathogens and parasites

• alteration of micro-climate, nutrient availability, ecoystem cycles (energy, water, minerals, organics)

• disturbance to ecological processes (e.g. pollination)

• disruption of ecosystem services (e.g. flood attenuation)

• environmental degradation, facilitating further invasions

economic impactsestimated at 5% global GDP

Direct costs

• Direct loss of crops, reduced yields

• Lost export earnings

• Loss of tourism revenues

• Management costs

Indirect costs

• Impaired ecosystem services

• Damaged infrastructure

• Costs to natural environment and societal or cultural values

health impacts

Direct impacts• Disease• Allergic reactions• Injuries through stinging or biting

Indirect impacts• Providing a vector for disease

ECOSYSTEM SERVICES

Supporting• Nutrient cycling• Soil formation• Primary production• …

Provisioning• Food• Fresh water• Wood and fiber• Fuel• …

Regulating• Climate regulation• Flood regulation• Disease prevention• Water purification• …

Cultural• Aesthetic• Spiritual• Educational• Recreational• …

Security• Personal safety• Secure resource access• Security from disasters

Basic material for good life• Adequate livelihoods• Sufficient nutritious food• Shelter• Access to goods

Health• Strength• Feeling well• Access to clean air & water

Good social relations• Social cohesion• Mutual respect• Ability to help others

Freedom of choice and action

Opportunity to be able to achieve what an individual values

being and doing

CONSTITUENTS OF WELL-BEING

Adapted from Millennium Ecosystem Assessment 2005

which results in changes in

impact on the provision of

invasions

understanding, assessing and acting on invasives in the light of the changes in ecosystem services and human wellbeing they give rise

toeconomic analysis

Millennium Ecosystem Assessment /Emerson & Howard

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

an example of spread and invasion impacts

In 1974 there was an occasional plant of

Mimosa pigra on the edges of the Kafue River

Kafue Floodplain, Zambia, dry

Kafue Floodplain flooded

1974

1974

The Kafue Floodplain was home to many wild animals and plants + cattle grazing, fishing, conservation& tourism

Mimosa pigra (continued)

A heavy flood in 1981/2 brought a few plants of Mimosa pigra on to the floodplain

(which was a new ecosystem changed by a dam upstream)

1982

Mimosa pigra (continued)

After a slow start in the late 1980s, M. pigra began to spread

By 2000 it was covering a few hundred hectares

2001

Mimosa pigra (continued)

By 2007 it was growing up to 4m high and covering 3,000 hectares

…. and excluding almost every other plant and most animals ….

2007

2007

Mimosa pigra continued

Today:

no livestock

no fisheries

no tourism on this part

of the Kafue

Floodplaincosts to

livelihoods & production

3,000 ha of an available 12,000 ha are now covered

invasion impacts – human development

Water hyacinth affecting Kafue Gorge Dam and hydropower station, Zambia (photo M. Mumba)

impacts on production (eco)systems

ecosystems, native or cultured, that are used for food and commodity production can

also be invaded by alien species

forestry, fisheries, agriculture, aquaculture

parasitism, pathogenesis, predation, competition,

exclusion and destruction of productive systems are all

recorded – most known from farming, horticulture and

livestock production

Tall trees of Senna spectabilis from S. America replacing native forest in Uganda

“Invasiveness” of an alien species

what makes a good invader?

•rapid growth rate

•great dispersal characteristics

•large reproductive capacity

•broad environmental tolerance

•effective competitor with local species

all invasive plants can be called “weeds”BUT not all weeds are invasive species

Lianes in Seychelles

current and future trends

human activities are changing natural ecosystems and making them more susceptible to IAS

• globalisation• land-use change• climate change

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

causes and effects of IAS are international or regional

IAS management and control supported by bilateral, regional and global instruments

and guidance (see Modules 2 & 6)

emerging principles of IAS management

• the precautionary principle

• the principle of preventive action

• the ecosystem approach

• sharing of information

• user-pays principle

• cross-sectoral approach to management

Parties to “prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species” (Art.8(h))

Convention on Biological Diversity 1992 (CBD)

Sharing of expertise and information is crucial

Types of information to be shared?

• Inventories and databases

• Incident lists and case studies

• Potential threats to neighbouring countries

• Information on taxonomy, ecology and genetics of IAS

• Prevention and control methods where available

• National and regional guidelines and measures

Many IAS databases accessible electronically

EAFRINET

The eastern Africa LOOP of BioNET-International                   

Some GISP products that can help