BACKGROUNDER April 2009 Web: www.invasives.org.au Email: [email protected] Invasive species: One of the top three threats to Australian biodiversity – Tim Low, Feral Future1
n Australia,1invasive species are one of the most Iubiquitous and severe threats to biodiversity. We are 6 5 5 5 notorious for having lost by far the highest number of = ` - a 6 & 6 5 Many bird species on islands have been wiped out by 6 – & @ ( ; B D 7 = > pathogen threatens hundreds 7 ( - 6 7 7 6 [ 7 7 - 7 7 L 7 Globally, invasive species have been recognized as the some cases.5 ( ( 7 2 mammals weighing between 35 grams and 5.5 & < 7 - N ous looming threat.3 7 R R The impacts of invasive species have been more severe [ ( 7 - 7 ' ), cats and 7 : ; - nent. And the worst is yet to come with most invasive honeybees. 7 [ 7 7 7 7 ) in considerably worsen their impacts. eastern Australia. The Invasive Species Council contends that along with [ & habitat loss, and now climate change, invasive species 7 7 ( ; - 8 cies, ecosystems and ecosystem processes. It is impor- 7 Invasive species have been the primary cause of animal 7 ; 0 that invasive species are one of the top threats to Aus- tralian biodiversity. @ @ 6 : @ - ( ; 7 V & 7 5 X D 0 6 DYZ& 9 6 : 6 : - L R L L L pl?wanted=fauna > 7
The Invasive Species Council campaigns to protect Australia’s environment from invasive species. To find out more about the council visit our website at www.invasives.org.au, or email us: [email protected]. Invasive species: One of the top three threats to Australian biodiversity
Mammals Frogs Darling Downs hopping-mouse Notomys mordax Southern platypus frog Rheobatrachus silus Big-eared hopping-mouse Notomys macrotis Northern platypus frog Rheobatrachus vitellinus White-footed tree-rat Conilurus albipes Sharp-snouted day frog Taudactylus acutirostris Great hopping-mouse Notomys sp. Southern day frog Taudactylus diurnus Gould’s mouse Pseudomys gouldii Northern tinker frog* Taudactylus rheophilus Broad-faced potoroo Potorous platyops Mountain mistfrog* Litoria nyakalensis
Eastern hare-wallaby Lagorchestes leporides Table 1: Extinctions of Australian vertebrate animals attributed sub- Short-tailed hopping-mouse Notomys amplus stantially to invasive species42. *presumed extinct, but not yet listed as such – last seen in 1991 and 1990 Notomys longicaudatus Long-tailed hopping-mouse respectively Lesser stick-nest rat Leporilus apicalis ( > They are Desert rat-kangaroo Caloprymnus campestris R_ Pig-footed bandicoot Chaeropus ecaudatus D Crescent nailtail wallaby Onychogalea lunata < R Central hare-wallaby Lagorchestes asomatus Desert bandicoot Perameles eremiana > Lesser bilby Macrotis leucura by invasive species, but these are not listed under the ` Eastern bettong (mainland) Bettongia gaimardi gaimardi 5 0 Burrowing bettong (inland) Bettongia lesueur graii 7 Brush-tailed bettong (south-east Bettongia penicallata penical- mainland) lata Threats to species Rufous hare-wallaby (south-west Lagorchestes hirsutus hirsutus > - mainland) cies in Australia… Banded hare-wallaby Lagostrophus fasciatus albipilis [ T 7 Western barred-bandicoot Perameles bougainville fasciata 6 Christmas Island rat Rattus macleari [ 7 Christmas Island rat Rattus nativitatis habitat Birds – Australian Academy of Science11 Vinous-tinted thrush Turdus poliocephalus vinitinctus > Zosterops strenuus Robust white-eye 7 ( - Lord Howe gerygone Gerygone insularis Grey fantail (Lord Howe Island) Rhipidura fuliginosa cervina Norfolk Island ground-dove Gallicolumba norfolciensis least one invasive species.12 Z 7 Y Tasman starling (Lord Howe Island) Aplonis fusca hulliana X 7 7 = Tasman starling (Norfolk Island) Aplonis fusca fusca from weed invasions, so the total number of federally Grey-headed blackbird Turdus poliocephalus polio- cephalus be much larger.13 Southern boobook (Norfolk Island) Ninox novaeseelandiae undulata Southern boobook (Lord Howe Ninox novaeseelandiae albaria Island) ( Z 7 V Long-tailed triller (Norfolk Island) Lalage leucopyga eucopyga ` 7R DYZ& ( 7LL L R L L L Red-crowned parakeet (Macquarie Cyanoramphus Novaezelandiae - Y 3`5}9(ZD> N&>) Island) erythrotis ` 7R DYZ& ( 7LL L R L L Buff-banded rail (Macquarie Gallirallus philippensis mac- L - Y ). Island) quariensis Z ( ( 7 : & X 7
Page 2 Threatened plant Threatened animal Endangered ecological Total* species species communities Anthropogenic destruction & 495 225 69 (96%) 820 (87%) disturbance of native vegetation Introduction of alien species 362 200 68 (94%) 657 (70%) Anthropogenic modification and 343 177 66 (92%) 611 (65%) degradation of abiotic factors ‘Natural’ phenomena 336 85 15 (21%) 449 (48%) Anthropogenic destruction & 0 121 4 (6%) 133 (14%) disturbance of native fauna Diseases 29 34 8 (11%) 75 (8%) Other threats 16 0 6 (8%) 2 (2%)
Table 2: Threatened biodiversity in New South Wales encompassed by each of the seven major threat categories in the threat hierarchy (Coutts- Smith and Downey 2006). *Note the total also includes threatened populations, which were not included in this table.
This conclusion is supported by a cursory review of the = 7 threat and the third-highest threat based on numbers of and animals listed under federal environmental legis- D } 7 weeds were the fourth-highest threat according to the DYZ& ( R_ Y 18 } 7 - DYZ& ( Y ( 7 - remainder are mostly threatened by disturbance or sto- } 7 7 DYZ& ( Y 7 15 - ( N: 7 7 ( & R: Y ( 5 X 7 9 ( 7 7 7 threatened ecosystems based on the number of biogeo- N: > Table 2). The highest threat category – anthropogenic 7 7 & R: X 7 T - N: 0 - 7 7 7 7 vidual threats such as land clearing, invasive species was weeds. the greatest threat. Close to half of threatened species 7 A very common threat scenario for ecological communi- per cent by feral animals. 7 7 7 land clearing and that fragments are then highly suscep- Threats by invasive species are highly ubiquitous – one of the top three, based on frequency across Austra- > ( 7 N 5 9 ( Threats to islands that feral animals were the highest threat based on & = 6 6 ` a 5 - 5 > DYZ& ( ) * - . T : V V & 7 > ( 5 7 7 Y ( Z 7 7 7 > : ( 7 : D - : ( = & R: X 7 & ( 7 N9B & R: X 7 programs, it was found to threaten only four species. V & 7
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Threatened Threatened Threatened Riparian zones DIWA wetlands species species ecosystems s &ERAL ANIMALS s 6EGETATION CLEARING s 'RAZING PRESSURE s 'RAZING PRESSURE s 'RAZING s #HANGED lRE REGIMES s 'RAZING PRESSURE s &ERAL ANIMALS s %XOTIC WEEDS pressure s 'RAZING PRESSURE s &ERAL ANIMALS s %XOTIC WEEDS s &ERAL ANIMALS s %XOTIC WEEDS s %XOTIC WEEDS s #HANGED lRE REGIMES s #HANGED lRE REGIMES s #HANGED HYDROLOGY s &ERAL ANIMALS s /THER s )NCREASING s )NCREASING s )NCREASING s #HANGED hydrology s )NCREASING FRAGMENTATION fragmentation fragmentation fragmentation s 0OLLUTION s 6EGETATION CLEARING s #HANGED HYDROLOGY s 6EGETATION CLEARING s #HANGED lRE REGIMES s 3ALINITY s #HANGED HYDROLOGY s %XOTIC WEEDS s #HANGED HYDROLOGY s 0OLLUTION s 0OLLUTION s 3ALINITY s 0ATHOGENS s 3ALINITY s &IREWOOD COLLECTION s &IREWOOD COLLECTION Table 3: Ranking of threats to aspects of biodiversity (Cork et al. 2006, citing Tait, unpublished report, drawing on NLWRA 2002). For columns 1, 3, 4 and 5 the ranking was based on the number of subregions reporting the threat. For column 2 the ranking was based on numbers of species per subregion reported to be threatened; DIWA = Directory of Important Wetlands in Australia. Globally, invasive species are typically the most serious threat to island biodiversity.21 Some islands are vulner- ( 5 9 - able because they have many endemic species with ( 7 7 <- overwhelmed by weeds or pests.22 } < 7 ; the threat.25 < V ( ; 9 R 7 listed wetlands Invasive species count as the dominant threat for ( 7 - 9 - 7 7 } 5 0 _ 7 L - cies are thought to have been wiped out mainly by = 7 rats, with many others surviving only on rat-free islands 7 nearby.23 Y B Christmas Island are currently undergoing precipitous 7 threat, 7 <7 of them.28 / ( B 7RX ). ` 7 * - } R 7 invasive species, and are playing that role for many Murray River. In Tasmania, trout threaten the survival of 7 - 0 the mainland. They are, however, highly vulnerable to ) and other invasive - 7 to Tasmania. & ZB> ZB Y 7 5 : within each site, but the magnitude of the impact was not assessed. D X 7 Y ( : 7 ` Z 7 @ @ X D & & N: V D ( > : :
Page 4 Ecological processes Examples of compromise by invasive species Climatic processes: flows of energy and matter through the The spread of flammable pasture grasses and other weeds increase atmosphere that drive precipitation, air temperature cycles and greenhouse gas emissions, eg. gamba grass fuels fires up to 8 times atmospheric pressure systems. hotter than natural fires, killing trees. Land system productivity: the rate of energy flows through Herbivores such as rabbits and goats can greatly deplete plant mass ecosystems, beginning with conversion of solar energy through and productivity. photosynthesis, into chemical energy in plant tissues. Hydrological processes associated with surface and sub-surface Weeds that dominate wetlands and waterways (eg. hymenachne) can water flows. alter hydrological processes, as can invasive trees (eg. willows) that take over river banks. Carp reduce water quality by stirring up mud and cause erosion of stream banks. &ORMATION OF BIOPHYSICAL HABITATS THROUGH PROCESSES INVOLVING .ITROGEN lXING WEEDS AND INVASIVE INVERTEBRATES IN THE LEAF LITTER CAN ALTER geological substrates, soils, vegetation and water. nutrient cycles in the soil. Interactions between species in food webs and in competition for &OXES AND CATS ARE HARMFUL PREDATORS OFTEN SUSTAINED BY HIGH RABBIT space and resources populations; weeds often outcompete other plants, and invasive animals EXERT HEAVY COMPETITION FOR RESOURCES SUCH AS FOOD HOLLOWS AND DROUGHT refugia. Movement of animals and seeds Degradation of habitats by invasive species can compromise the move- ment of migrating animals, and many invasive animals affect the dispersal of seeds, either by reducing seed dispersers or dispersing seeds them- selves. #OASTAL ZONE mUXES MOVEMENTS OF ENERGY AND NUTRIENTS BETWEEN 7EEDS SUCH AS BITOU BUSH AFFECT COASTAL ZONE mUXES BY CHANGING DUNE land and sea, and sea and land. dynamics. Table 4: Invasive species and ecological processes.43 Key threatening processes processes listed by the federal and state governments. } 7 7 DYZ& ( 7 7 vertebrate pests, two for invertebrate pests and three 7 B - } 7 ( ; 7 N: - south-west Western Australia are regarded as suscep- : - 7 ; 35 .31 D 7 7 ) could also have a dire impact if it was introduced.32 It infects plants 7 B7 Threats to ecosystem processes and shrub species in Australia, including eucalypts and Invasive species compromise ecological processes, 7 - : - R 7 vertebrates, including 12 threatened species, in Tasma- movements of energy, nutrients and other chemical nia if not eradicated.33 ; T 7 7 : - ; 7 ` ( R - 7 7 > drought refugia. As a dominant food source in many < 7 7 which in turn impact on other species. Invasive species also compromise all the other ecosystem processes in
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up in natural bushland as threats to biodiversity. And as 5 7 ( ; & - 7 5 - 6 - 6 ^ _ 5 – Tim Low, Feral Future 5 R - The full impacts of most invasive species already in Aus- - 7 7 ^ ' to establish and then reach their full range.38 Moreover, 6 _ 7 T There is no one indicator of threats to biodiversity by 7 &: 9} The establishment of an Z _- uity of impacts of invasive species on species, ecosys- It is impossible to predict the impacts of many invasive tems and ecological processes strongly suggests they are - one of the top threats to biodiversity, along with habi- = = ( It is important to more comprehensively assess the 7 7 7 - 7 7 will become more vulnerable. Some invasive species - tures. References ( Z 7 V Y X 7 : : ( & - 7 &9& Y ( & &9& ( Z 7 B ` ( 7LL the overall impacts of invasive species on Australian L L(ZV : L biodiversity, they tend to be under-rated in popular 7 > ( : 7 ` Z 7 > comprehensive review of threatened species adversely ( : 7 ` Z - 7 N: 7 N 7 R > 7 R ? Z 9 ( ( 7 : 7 ( ; ( > ( 7 : 7LL L LL 7 there has been strong public support for controls on ZB> ZB Y 7 5 > 9 : : 7 7 = 7 T R ` 9 & 7 X D - land clearing – there has been limited public pressure 9 7LL on governments to enact controls on invasive species. L L L L L > 7 = 7 ramsar-snapshot-study.html. invasive species harmful to biodiversity – gardeners and & 7 Y V 90 Z 9 D farmers can freely plant hundreds of weeds that will end X 7 X 7 R & ( X 5 7 X & 7 < : ( 7 natural ecosysstems caused by - < 7 - 7 7 &: 9} 5 &
Page 6 & 7 X 0 L L L 7 R L the Arts. _ R 7 L L L R & : : Y ( @ Z 7 V B ( (& < D( B@ B - 7 ( : & Y 7 ( D & & 7 X - environment and economy - a review. Australasian D 0 Y Y 7 7 R &: 9} : ` : - @ YX @X 9 ( ; - _ 7 R ( : 7 ` Z - D Y 7 0 D : ` Z 7 & ( Sustaining Fish Habitats. Australian Society for Fish : Z & 7 Y ( Z 7 Y 0 :( L L L Z L - R ( & 7 Z 9 : Z _ LR L Z L - @ & ( ; B D 7 ( L 7 77 & 7 Y & : ( 5 > ` ` 7 > : 7 ( - of - ; D B 7 Y 7 Z - 7 X N 9 & 7 & 7 X D - X D & & ment, Heritage, Water and the Arts. www.environ- N: 5 0 Z 7 B - L 7L L R Y :7 77 N: V cc-invasive.html. X Y 7 B V ( & 7 Z X & V 9 - ` > R ( @ D 7 7 7LL L L Y L 7 N 7 :@}NR @ Alliance. X D 0 N: : & Z 7 7 R 7 7 - N: V X - 7 7 & 7 XD0 ( D & & 7LL Government. L LD - X 7 5 } 9 : > Y V >Y5 7 Y D 7 : }> : Y@ ( 7 & @B Z X> X@ 5 B B many aspects of the invasive alien species problem. 5 : @ Y Y R : Z 7 B - :7 Z & & 7 : ( ( R B 7 : 9 > B ( & 7 X 7 Y} X 9 Z 77 N : ( Y R > &X D > RV < Z Z @ Z V & 5 N 7 R & Y7 Y Y 7 > : : 9 7 Y 7 > - 5 7 Z - V R 0 7 X 7 Y Y 7 D ( & N Z : ( - Y B Y & 7 ( V - 7LL L L - 7 & D 7 L L R 7 V :> & 7 VB > ( Y ( - X: 9 @ X @ Y ( 5 D Z & 7 D ( 7 V X ` 5 B 7R : Z 7 R X 7 : N 7 9 > & N: X Y 7 7LL N D Y
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