Biological Invasions:The Human Dimension

Philip HulmeNERC Centre for Ecology & Hydrology

Terminology

Alien: A species that is not native to a country, region or habitat. Alternative terms include exotic, non-native and non-indigenous species (NIS)

Naturalised: A species that is able to maintain a self-replacing population in a region where it is non-indigenous.

Invasive: A species whose local abundance and/or geographic distribution is increasing, often in areas where it was previously absent.

Current concern relates to biological invasions that result from human activities (introduction, habitat modification) although an increasing focus on unwanted natural colonisation events.

Alien impacts: non-native flora

Campylopus introflexusReduces Calluna regeneration

Rhododendron ponticumReduces species richness

Picea sitchensisEcosystem change

Hyacinthoides hispanicaHybridization with natives

Ambrosia trifidaHealth risk

Oxalis pes capraeEconomic damage

Alien impacts: non-native fauna

Arthurdendyus triangulatus Earthworm predator

Arion lusitanicusEconomic damage

Cervus nipponHybridization with natives Fallopia japonica

Wildfowl predator

Sciurus carolinensisWildlife disease

Branta canadensisSocial and economic pest

Bioinvasions in a global context

Millennium Ecosystem Assessment: Ecosystems and Human Well-being – Synthesis

2005

International policy and invasions

The European States have a commitment to:

“strictly control the introduction of non-indigenous species”

Bern Convention on the Conservation of European Wildlife & Natural Habitats

“eradicate those alien species which threaten ecosystems, habitats or species”UN Convention on Biological Diversity

“ensure that the deliberate introduction into the wild of any species which is not native to their territory is regulated so as not to prejudice natural habitats within their natural range or the wild fauna and flora and, if they consider it necessary, prohibit such introduction”European Union Habitats Directive

Risk Assessment

LIKELIHOOD

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Strength of PathwaysEstablishmentPopulation GrowthDispersal

HIGHRISK

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LOWRISK

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Driving Forces: Transport & trade

Greater connectivity through travel and trade provides opportunties for aliens

Ponto-Caspian invasions Canal & river network link Black & Caspian to North & Baltic seas

Lessepsian invasionsSuez Canal opened in 1869 links Red & Mediterranean Seas

Understanding pathways: entry routes

How many routes lead to species introductions?Contaminants of agricultural & aquacultural produceContaminants of commercial grain suppliesSeed contaminants of nursery & cut flower tradeOrganisms on timberSeed contaminants of soilMachinery, equipment, vehicles, aircraftContaminants of packing materialsContaminants of mail and cargoBallast soilBallast waterHull foulingTourists and their luggageOther

Sources on non-native plants in the UK

Garden Escape

Seed Contaminant

Feral Crop

Landscaping

Aquarium EscapeMedicinal Herb

Forestry

Other

Pressures: land-use change & disturbance

Disturbance, fragmentation, eutrophication increase ecosystem vulnerability

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Trends in invasion impacts

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Strongly negative Negative Positive Strongly positive No effect

Economic impact

Nu

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Animals

Plants

Fungi & microbes

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Strongly negative Negative Positive Strongly positive No effect

Environmental impact

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Assessing impacts: invader removals

X

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American minkMustela visonNordstom et al. 2002

Himalayan BalsamImpatiens glandulifera

Hulme & Bremner 2006

Wire weedSargassum muticum

Sanchez & Fernandez 2005

Raccoon dogNyctereutes procyonoides

Kauhala 2004

Removal experiments are rare but necessary to assess correlative studies

Risk Assessment

LIKELIHOOD

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Strength of PathwaysEstablishmentPopulation GrowthDispersal

HIGHRISK

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LOWRISK

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MEDIUMRISK

LOWRISK

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Likelihood

Impact

Integration

Very unlikely Unlikely Possible Likely Very likelyMinimal

Minor

Moderate

Major

Massive

Likelihood

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Aliens are often difficult to define

Regional versus national perspectivesThe beech and hedgehog

are viewed as both native and alien

Established aliens part of countrysidePheasants and horse chestnuts

Are accepted as part of UK wildlife

Reintroductions Beavers and Norway spruce

Once native to UK, so why not again?

King Crab: Paralithodes camtschaticus

Commercial king crab fisheryYear Catch Value2002 100K 67 million

NOK2003 200K 93 million

NOK2004 280K

Managing species: public perception

0100200300400500600700800900

1000

1940 1950 1960 1970 1980 1990 2000 2010

Year

Area

(km

2)

ConclusionsThe field of biological invasions has grown dramatically in last 20yrsHigh profile has raised public expectations of scientific deliverablesScience needs move from quantifying problems to identifying solutionsSeveral key areas include:1. Quantifying the spatio-temporal dynamics at appropriate scales2. Implementing robust monitoring strategies for rapid response3. Identifying major tools & approaches to accurate risk assessment4. Developing management guidelines based on ecological strategiesPolicy relevant science should still equate with cutting-edge research