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Workshop on biofuel production and invasive species, IUCN Wasaa, Nairobi, Kenya, 20th to 22nd March, 2009 The Invasive Species Context: general principles Geoffrey Howard IUCN Global Invasive Species Coordinator IUCN Nairobi, Kenya Q: What are invasive alien species? A: Biological entities that come to a new area and cause ecosystem degradation There are many different terms and definitions in this complex (and sometimes disputed) area – so we will use the following general definitions: •! An alien species is one that is introduced to a new location (ecosystem or area) where it does not occur naturally (i.e. non-native, non-indigenous) •! An invasive alien species (IAS) is an alien species that causes (or has the potential to cause) harm to biodiversity, the environment, economies and/or human health FROM HERE-ON: we will call them: “invasive species” = IS (to make life easier!) introductions are nothing new... Natural movement of species has been going on for thousands of years ...but globalisation has led to massive expansion of opportunities for introductions what types of species invade? from all taxonomic groups •! vertebrates (e.g. mammals, fish, birds, amphibians, reptiles) •! invertebrates (e.g. insects, crustaceans, snails, worms) •! aquatic and terrestrial plants (e.g. ferns, mosses, herbs, shrubs, trees) •! micro-organisms (e.g. viruses, bacteria, yeasts, protozoa, protophyta) The Process of Invasion 1. Introduction – intentional or unintentional 2. Establishment – survives but doesn’t spread (a) naturalisation – becomes part of new habitat’s flora/fauna 3. Spread (b) invasion – expands and impacts on species, ecosystems people and development 1. Introduction 2. Establishment 3a.Spread - Naturalisation 3b. SPREAD - INVASION the House Sparrow (from Asia) 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 Population size 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 Introduction Invasion Carrying capacity Lag phase Time 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 •! Sequence endorsed under Convention on Biological Diversity (CBD Guiding Principles for IAS management) how do species get moved around? Vectors: The specific mechanisms 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 introduction of (alien) species Movement by human action of a species outside its native range can result in introduction (into/within a country or ecosystem) Some establish, naturalise and spread Some establish, naturalise and spread intentional introduction for food, agriculture, forestry, horticulture, fisheries, hunting, ornamental and for pleasure ... unintentional introduction species that move with other imports as ‘hitchhikers’ or ‘stowaways’ Impacts of Invasive Species negative impacts on: •! ecosystems •! economies •! human health Ecological and biodiversity impacts •! direct predation/herbivory •! competition for resources/exclusion (e.g. light, food, water, space) •! transmission of pathogens and parasites •! alteration of micro-climate, nutrient availability, ecosystem 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 impacts estimated 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 •! Poisons Indirect impacts •! Providing a vector for disease Lantana camara is a classic IS which (after 160 years) is still spreading across Africa and invading new lands - as well as in Australia, Asia and North America Intentionally introduced from tropical America for its flowers, it is now spread by birds and small mammals Lantana replaces native vegetation and pasture, is poisonous to livestock and harbours tsetse flies and rats an example of spread and invasion impacts Kafue Floodplain, Zambia, dry 1974 Kafue Floodplain flooded 1974 The Kafue Floodplain was home to many wild animals and plants + cattle grazing, fishing, conservation & tourism In 1974 there was an occasional plant of Mimosa pigra on the edges of the Kafue River 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) By 2007 it was growing up to 4m high and covering 3,000 hectares 2007 2007 …. and excluding almost every other plant and most animals …. as well as fisheries, tourism… Invasion impacts – human development Introduced from tropical America for its flowers 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 Tall trees of Senna spectabilis from S. America replacing native forest in Uganda parasitism, pathogenesis, predation, competition, exclusion and destruction of productive systems are all recorded – most known from farming, horticulture and livestock production “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 Invasive lianes from Asia in Seychelles Arne Witt will enlarge on this topic all invasive plants can be called “weeds” BUT not all weeds are invasive species 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 Invasive Species are international or regional IS management and control is supported by bilateral, regional and global instruments and guidance Convention on Biological Diversity 1992 (CBD) Parties to “prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species” (Art.8(h)) 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 Other instruments and guidance International Plant Protection Convention African Convention on Nature and Natural Resources NEPAD Environmental Programme Roundtable on Sustainable Biofuels Invasive Species Specialist Group of IUCN The Global Invasive Species Programme (GISP) www.gisp.org 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 are accessible electronically EAFRINET The eastern Africa LOOP of BioNET-International THANKS FOR YOUR ATTENTION Ethiopian camel pasture and native vegetation invaded by two alien species of Opuntia (introduced cactus)