National recovery plan for the Bertya sp. (Cobar-coolabah)

Cunningham & Milthorpe s.n., 2/8/73
NSW National Parks and Wildlife Service , July 2002
ISBN 0 7313 6517 8

7. Management Issues

7.1 Threats and Reasons for Decline
7.2 Social and Economic Considerations
7.3 Biodiversity Benefits
7.4 Species Ability to Recover
7.5 Current Ex-situ Programs

Within far-western NSW, one population has disappeared and the remaining population near Coolabah is senescent and appears to have declined in size. The Jacks Creek State Forest and Kangaroo River State Forest populations appear stable (although seedlings are few in the latter), and the Gibraltar Range National Park population is small and senescent. Potential threats to the species vary between sites but include grazing, inappropriate disturbance and fire regimes, clearing, and drought.

7.1.1 Grazing

Feral goats have been observed grazing on coppicing stems at the base of trunks as well as standing erect to browse on the lower branches of Bertya sp. Cobar-Coolabah. at the Coolabah site. Grazing by goats may also be responsible for the lack of seedlings at the site. There is no evidence that grazing by native or introduced herbivores occurs in the other three populations.

7.1.2 Disturbance

The lack of seedlings observed in the Coolabah and Gibraltar Range National Park populations suggests that either seedlings are being removed or the necessary germination cues are not present. The Coolabah population has not been disturbed by fire for at least 25 years and perhaps 40 years (A. Loffler pers. comm.). While the germination cues at three of the sites are not known, fire and disturbance appear to trigger germination at Jacks Creek State Forest where seedlings are abundant. Disturbance can stimulate seed banks and create a trigger for germination.

7.1.3 Fire

The response of Bertya sp. Cobar-Coolabah to fire is not known. There is some indication that the species may resprout from the roots following disturbance. There is prolific regrowth of plants following grading of the fire break adjacent to Jacks Creek State Forest.

Kangaroo River State Forest is burnt on a 3-5 year burn cycle at an intensity high enough to remove fine fuel loads (Coffs Harbour Management Area EIS 1995). The burn is broad scale and is not controlled within compartment boundaries. The last recorded fire in the compartment that contains the Bertya sp. Cobar-Coolabah population was in November 1994. Although the population itself is confined to a rock outcrop and is not burnt, burning the surrounding area may prevent expansion of the Bertya population by eliminating any seedlings or suckers that do appear.

7.1.4 Clearing

While the four populations are not under serious threat from broad scale clearing, small scale clearing may occur in the Jacks Creek State Forest area along road verges as part of trail/firebreak maintenance and to establish sites for apiarists. The freehold land adjoining Jacks Creek State Forest has largely been cleared for grazing, but Bertya sp. Cobar-Coolabah still exists in unmodified areas on some properties. Bertya sp. Cobar-Coolabah appears resilient to temporary clearing with regrowth common. The coastal populations are relatively protected from future clearing as both are inaccessible

7.1.5 Drought

While drought alone may not be a sufficient mechanism to negatively impact on Bertya sp. Cobar-Coolabah populations, it may act in concert with other disturbance factors, particularly when it is for an extended period, and result in reduced seedling recruitment and increased juvenile mortality, particularly in the western semi-arid woodland areas. The assumed disappearance of the population near Cobar may have been related to the extreme drought throughout the 1980's, which may have killed off any seedlings that germinated following the 1984 bushfire (L. Miller pers. comm.). While the coastal populations are relatively drought free, given the generally reliable rainfall on the coast, they can be subject to significant spring droughts in some years and stands on rock outcrops may be more subject to water stress than western stands on deeper soils.

7.2 Social and Economic Considerations

Bertya sp. Cobar-Coolabah has no known commercial value and no Bertya species are used in horticultural cultivation (Wrigley and Fagg 1996). Any adverse social and economic consequences resulting from the implementation of this plan are either unknown or insignificant. Submissions from the community and concerned stakeholders regarding the social and economic impacts of this plan will be welcomed during the public exhibition period.

Threatened species & ecological communities