NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. Bothriochloa biloba, a perennial grass, was included on Schedule 2 of the Threatened Species Conservation Act when it came into effect on January 1 1996. Bothriochloa biloba occurs in a variety of grassland and woodland associations. The species has a broad distribution in northern New South Wales, but most records have been from the northern portions of the Brigalow Belt South and Nandewar bioregions.
2. The majority of confirmed herbarium specimens of Bothriochloa biloba have come from roadsides and travelling stock routes. Recent targeted surveys and intensive flora surveys within the known range of the species have located many more occurrences, including areas away from roadsides (e.g. paddocks and travelling stock reserves) (Bean 1999, Hunter and Earl 1999, Earl and Kahn 2001, Austen 2002, NSW National Parks & Wildlife Service 2002). The abundance and distribution of the species now appears to be greater than is indicated by previous records.
3. A number of records of Bothriochloa biloba are also known from stands of the Endangered Ecological Community 'White Box Yellow Box Blakely's Red Gum Woodland' (Earl and Kahn 2001, Austen 2002).
4. There are conflicting views on the response of B. biloba to grazing. At some sites the species appears to tolerate some grazing (Bean 1999; Earl and Kahn 2001) and it may persist in areas that are regularly slashed and mowed (Bean 1999; S. Lewer, pers. comm.). Indeed, in areas without grazing, other perennial grasses (such as Aristida ramosa) may competitively exclude Bothriochloa biloba (Bean 1999). However, the species appears to be more prevalent in areas that are conservatively grazed e.g. on roadsides and travelling stock routes (W. Hawes, pers. comm.; A. Eade, pers. comm.) or rotationally grazed (B. McGufficke, pers. comm.), which suggests that overstocking may act to the detriment of the species.
5. Bothriochloa biloba shows a preference for heavier textured soils (Bean 1999), which are favoured for clearing and conversion to cultivation. There is evidence that Bothriochloa biloba may successfully recolonise cultivated areas provided the period of cultivation was no greater than four to five years, but the success of recolonisation by the species after longer periods of cultivation is believed to be low (Earl and Kahn 2001).
6. Invasion and competition from Coolatai Grass, Hyparrhenia hirta, and other exotic perennial grasses are a potential threat to Bothriochloa biloba (Earl and Kahn 2001; J. Hunter pers. comm.). In particular, the potential spread of Coolatai Grass along travelling stock routes is a major threat to the species (J. Austen, pers. comm.). The potential impacts of soil disturbance in road reserves and altered fire regimes in association with land use changes are unknown.
7. Bothriochloa biloba remains listed as a Vulnerable Species under both the Commonwealth Environmental Protection & Biodiversity Conservation Act and the Queensland Nature Conservation Act.
8. Notwithstanding points 5, 6 and 7 above, at the present time the known distribution and abundance of Bothriochloa biloba is such that it is not likely to become endangered. However, future review of the circumstances and factors that may threaten the survival or evolutionary development of the species will be required.
9. The Scientific Committee is of the opinion that Bothriochloa biloba S.T. Blake does not currently satisfy the criteria for listing as a Vulnerable Species and hence should be removed from Schedule 2 of the Threatened Species Conservation Act.
Associate Professor Paul Adam
Chairperson
Scientific Committee
Proposed Gazettal date: 02/04/04
Exhibition period: 02/04/04 - 14/05/04
References:
Austen JR (2002) 'The conservation value and identification of biodiversity on travelling stock routes and reserves of north west New South Wales.' North West Rural Lands Protection Boards, Narrabri, NSW.
Bean JM (1999) Bothriochloa biloba (Poaceae) in natural grasslands on slopes of the Liverpool Plains, New South Wales. Cunninghamia 6, 383-387.
Earl J, Kahn L (2001) 'Field survey of Bothriochloa biloba S.T. Blake North-west Slopes NSW.' Report to the NSW National Parks & Wildlife Service, Dubbo, NSW.
Hunter JT, Earl J (1999) 'Floristic descriptions of Grassland areas on the Moree Plains.' NSW Department of Land & Water Conservation, Inverell, NSW.
NSW National Parks & Wildlife Service (2002) 'Targeted Flora Survey And Mapping. NSW Western Regional Assessments, Brigalow Belt South Bioregion (Stage 2).' NSW Resource Conservation & Assessment Commission, Sydney.