Weed risk assessment of twenty plant species used for revegetation or farm forestry in South Australia

摘要

Concerns have been raised over the weed risk to natural ecosystems potentially created by the mass planting of revegetation species in South Australia. A weed risk ranking system devised by the Animal and Plant Control Commission (APCC) of South Australia (SA) was applied to 20 species which have been or are being used for revegetation and which were nominated for investigation by the SA State Revegetation Committee. The system considers the invasiveness, impacts and potential distribution of each species to give a weed importance score, and in this case the focus was on potential threats to areas of native vegetation in SA. Weeds were scored based on information collected from a widely distributed questionnaire, the SA herbarium, field observationsacross the state and from GIS analysis of climatic and soil preferences. On a statewide scale, species which scored as a very high weed risk to native vegetation were; Pinus halepensis (Aleppo pine), Pinus brutia (Calabrian pine), Acacia saligna (goldenwreath wattle), and Ehrharta calycina (perennial veldt grass). Acacia cyclops (western coastal wattle) scored as a high weed risk. Pinus radiata (Monterey pine) and Casuarina glauca (swamp sheoak) were medium weed risk species. Species which scored as alow weed risk were: Eucalyptus globulus (Tasmanian blue gum), Eucalyptus cladocalyx (sugar gum), Eucalyptus platypus (round leaf moort), Chamaecytisus palmensis (tagasaste), Medicago sativa ssp. sativa (lucerne), Thinopyrum ponticum (tall wheatgrass) and Puccinellia ciliata (perennial sweet grass). Species which had negligible weed risk were: Eucalyptus grandis (flooded gum), Eucalyptus occidentalis (flat-topped yate), Eucalyptus saligna (Sydney blue gum), Atriplex nummularia ssp. nummularia (old man saltbush), Atriplex amnicola (river saltbush), and Themeda triandra (kangaroo grass). Implications for the future use and management; of these species in South Australia are discussed.