Plant Protection Quarterly Vol.11(4) 1996 143 widespread. However, this information is Emex australis in Western Australia; an amenity or contained largely in the ‘grey’ literature of management plans, interim plant lists and conservation problem? internal reports. Emex is probably more common in many states since all recent Greg Keighery, Department of Conservation and Land Management, ecological studies of reserves and pastoral PO Box 51, Wanneroo, Western Australia 6065, Australia. lands in semi-arid New South Wales (Morcom and Westbrooke 1990, Port- eners 1993, Westbrooke and Millar 1995) Abstract list Emex. The impact and invasiveness of Emex australis is widespread in Western its potential impact on these areas. This this species is unfortunately never dis- Australia, with numerous records from paper attempts to briefly review what is cussed. most large national parks and nature re- known about the occurrence and potential serves. Generally found only in highly impact of E. australis on conservation in The situation in Western Australia disturbed sites (roads, tracks, firebreaks, Australia. picnic sites, old homesteads and clear- Conservation lands ings) in conservation reserves. On pasto- The situation in eastern Australia Again most information is from the grey ral properties it is also mainly found on Because of its impact on agriculture, Emex literature and personal observations. tracks, stock pens and watering points. australis is a declared noxious weed in There are numerous records from most Natural areas invaded by Emex include most of Australia. However, it barely rates large national parks and nature reserves, edges of creeks, riverine flats, alluvial a mention in lists of major environmental south of the Pilbara (Table 2). Emex was flats (claypans, edges saline lakes) and weeds of Australia, as detailed in also frequently cited as a problem by granite rocks. These are the sites of bio- Humphries et al. (1991) and Swarbrick and CALM operations staff from all regions logical diversity and refugia in arid Skarratt (1994). south of the Pilbara (Goble-Garratt and Western Australia. Emex is also recorded At the regional level Emex is also con- Keighery 1992). as a major weed of naturally disturbed sidered largely an agricultural weed. Generally Emex is found only in highly seabird rookeries of the Abrolhos Is- Smith (1995) does not list it for the North- disturbed sites (roads, tracks, firebreaks, lands. ern Territory. Kleinschmidt and Johnson picnic sites, old homesteads and clear- Emex has become a food source for (1977) list it as a weed of ‘disturbed sites ings), and in parks subjected to past or Major Mitchell cockatoos, inland red around buildings, cultivated paddocks present grazing (Pigott 1988). Emex is re- tailed black cockatoos, galahs, little and and along roadsides’ for Queensland as corded as a major weed of naturally dis- long billed corellas in the largely cleared does Wilson (1990) for New South Wales. turbed and nutrient enriched seabird northern wheatbelt. Carr et al. (1992) list Emex for Victoria as of rookeries of the Abrolhos Islands. ‘limited distribution and occurring in Introduction small populations, but list it as a serious Pastoral lands Emex australis is a widespread weed in threat to lowland grassland and grassy Curry and Hacker (1990) state ‘A number southern Australia, and especially in woodlands.’ Kloot (1986) lists it as wide- of exotic species have become established, Western Australia. Where it is found from spread weed of cereal crops for South but most have not become more than a the Great Sandy Desert to the Nullarbor. Australia, but not for native vegetation. minor component of the vegetation. The species is absent from the Kimberley Keighery (1995) lists Emex as a ‘wide- Amongst the more widespread introduc- (there is one record from the Kununurra spread weed of agriculture, wasteland, tions are the doublegee (Emex australis), Research Station), very uncommon in the tracks, occasional in grazed woodlands Ward’s Weed (Carrichtera annua) and one Pilbara and the wetter regions of the and granite rocks’ for Western Australia. perennial grass (Cenchrus ciliaris). Nearly south-west forests. Despite its wide range However, as shown in Table 1, Emex is all of the common exotic species grow there is little information on this species frequently recorded from conservation ar- mainly on highly disturbed sites which occurrence in conservation reserves and eas in all mainland states where it is have either undergone soil redistribution Table 1. Emex in eastern Australian conservation parks and bushland. Northern Territory Uluhru National Park. Queensland Present, but unrecorded in many conservation reserves in arid and semi- arid regions, usually in disturbed sites. New South Wales National Parks in semi-arid Western New South Wales. Victoria Minor weed, scattered in grassland and grassy woodland remnants, parks and reserves in Mallee Region. Tasmania Only Flinders Island (Bass Strait). South Australia National Parks in semi-arid (e.g. Flinders Ranges), coastal dunes, offshore islands and roadsides. Table 2. Emex in Western Australian conservation parks and bushland. Kimberley One record from Kununurra. Pilbara No records, rarely recorded from conservation areas (S. van Leeuwen personal communication.). Desert Rudall River, Cape Range, Mount Augustus, Kennedy Range, Zuytdorp, Francois Peron, Goongarrie and Boorabbin National Parks. Wanjarrie Nature Reserve. Mount Elvirie State Forest. Northern sandplains Kalbarri National Park (major weed along Murchison River flats), many nature reserves, Abrolhos Islands. Wheatbelt Lake Magenta Nature Reserve, many other nature reserves (D. Mitchell personal communication). Swan and forests Scattered records in reserves and offshore islands around Perth. Tuart Forest and Leeuwin-Naturaliste National Parks. Karri and south coast Scattered records in reserves, National Parks and offshore islands from Denmark to Cape Arid (J. Moore per- sonal communication). Eucla National Park. 144 Plant Protection Quarterly Vol.11(4) 1996 Table 3. Areas affected. Pigott, J.P. (1988). The dominance of intro- duced species in the understory of Disturbed Sites: Previously heavily grazed Tuart Forest near Ludlow, Western Stock holding pens Australia. Australian Weeds Research Old building sites Newsletter 37, 57-63. Tourist sites Porteners, M.F. (1993). The natural vegeta- Firebreaks, tracks tion of the Hay Plain: Booligal-Hay and Watering points Deniliquin-Bendigo 1:250,000 maps. Riverine Sites Cunninghamia 3, 1-122. Alluvial Flats: Claypans Rowley, I. (1990). Behavioral ecology of Edges saline lakes the galah (Eolophis roseicapillus) in the Granite Rock Margins wheatbelt of Western Australia. (Sur- Semi-arid Islands: Seabird colonies rey Beatty and Sons, Sydney). Fisherman settlements Saunders, D.A. and Ingram, J. (1995). ‘Birds of south-western Australia’. (Surrey Beatty and Sons, Sydney). or nutrient enrichment, such as on de- does, however, invade naturally disturbed Saunders, D.A., Rowley, I. and Smith, G.T. graded or eroded areas or in stockyards and high productivity areas in arid and (1985). The effects of clearing for agri- and holding paddocks. Exotic species are semi-arid Western Australia, which can be culture on the distribution of cockatoos generally rare or absent in areas not other- of considerable conservation significance. in the southwest of Western Australia. wise degraded’. There is little known about the effects of In ‘Birds of eucalypt forests and wood- On pastoral properties it is found on such invasion in these remote areas. lands : ecology, conservation and man- tracks, stock pens and watering points. agement’, eds A. Keast, H.F. Recher, H. Natural areas invaded by Emex in the pas- References Ford and D.A. Saunders, pp 309-321. toral zone are edges of creeks, riverine Carr, G.W., Yugovic, J.W. and Robinson, (Surrey Beatty and Sons, Sydney). flats, alluvial flats (claypans, edges saline K.E. (1992). Environmental weed inva- Smith, N.M. (1995). ‘Weeds of natural eco- lakes) and granite rocks. sions in Victoria. Department of Con- systems: A field guide to environmen- servation and Environment and Eco- tal weeds of the Northern Territory’. Areas impacted logical Horticulture, Melbourne, Victo- (Environment Centre, Darwin, North- Table 3 lists areas and habitats affected by ria. ern Territory). Emex. While it is true that highly disturbed Curry, P.J. and Hacker, R.B. (1990). Can Swarbrick, J.T. and Skarratt, D.B. (1994). sites predominate, some naturally dis- pastoral grazing management satisfy ‘The Bushweed 2 database of environ- turbed sites such as seabird rookeries are endorsed conservation objectives in mental weeds in Australia’. (University invaded and Emex has become a major arid Western Australia? Journal of Envi- of Queensland Gatton College, Gatton, weed of the Abrolhos Islands. These is- ronmental Management 30, 295-320. Queensland). lands contain some of the largest rooker- Goble-Garratt, E.M. and Keighery, G.J. Westbrooke, M.E. and Millar, J.D. (1995). ies in Australia. (1992). Review of environmental The vegetation of Mungo National Natural areas invaded by Emex are weeds. (Department of Conservation Park, western New South Wales. edges of creeks, riverine flats, alluvial flats and Land Management, Western Aus- Cunninghamia 4, 63-80. (claypans, edges saline lakes) and granite tralia, Como, Western Australia). Wilson, K. (1990). Polygonaceae. ‘Flora rocks. These are the areas recognized by Humphries, S.E., Groves, R.H. and New South