Conservation Advice Callistemon Kenmorrisonii Betka Bottlebrush
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THREATENED SPECIES SCIENTIFIC COMMITTEE Established under the Environment Protection and Biodiversity Conservation Act 1999 The Minister’s delegate approved this Conservation Advice on 16/12/2016 . Conservation Advice Callistemon kenmorrisonii Betka bottlebrush Conservation Status Callistemon kenmorrisonii (Betka bottlebrush) is listed as Vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth) (EPBC Act) effective from the 16 July 2000. The species was eligible for listing under the EPBC Act as on 16 July 2000 it was listed as Vulnerable under Schedule 1 of the preceding Act, the Endangered Species Protection Act 1992 (Cwlth). This species can also be listed as threatened under state and territory legislation. For information on the current listing status of this species under relevant state or territory legislation, see http://www.environment.gov.au/cgi-bin/sprat/public/sprat.pl The main factors that are the cause of the species being eligible for listing in the Vulnerable category are that the species has a limited extent of occurrence and area of occupancy, and a very small population size. Description The Betka bottlebrush is an erect to spreading shrub to 3 m tall and 1 - 4 m wide with spongy, papery bark. The leaves are narrowly lance-shaped, to 52 mm long by 6 mm wide, hairless, stiff and leathery. Bright red flowers with purple anthers form dense bottlebrush-like spikes to 100 mm long by up to 60 mm wide in the upper parts of younger stems. Flowers appear between November and February. The fruiting capsules are woody and cup-shaped, to 9 mm wide and are clustered along older stems (Molyneux 1995 cited in Carter & Walsh 2006 ; Walsh & Entwisle 1996 cited in Carter & Walsh 2006). The Betka bottlebrush resembles the closely related Callistemon subulatus (dwarf bottlebrush) and C. citrinus (crimson bottlebrush), which occur in the local region (Molyneux pers. comm. 2016). While the Betka bottlebrush and the crimson bottlebrush grow to the same size, the dwarf bottlebrush is more compact and tends to only grow to a height of about 1 m (Harden 2002). The leaves (30 - 70 mm long by 5 - 8 mm wide), flower spikes (60 - 100 mm long by 40 - 70 mm wide) and fruiting capsules (4 - 7 mm wide) of the crimson bottlebrush are generally larger than those of the Betka bottlebrush and dwarf bottlebrush (Harden 2002; Walsh & Entwisle 1996 cited in Carter & Walsh 2006). Distribution The Betka bottlebrush is a naturally rare species that is endemic to a small area in the coastal lowlands of East Gippsland, Victoria. The species is known to occur only at two sites on the Betka River near Mallacoota at elevations ranging between approximately 100 and 120 m above sea level. One site is located just downstream of Stony Peak Road and the other about 9 km downstream where Roger Track crosses the river (Molyneux 1997 cited in Carter & Walsh 2006; Molyneux pers. comm. 2016; Walsh unpubl. cited in Carter & Walsh 2006). Monitoring of these sites was last conducted in 2007, 38 plants were counted at the Stony Peak Road site and 25 plants (DSE 2007a) were counted at the Roger Track site (DSE 2007b). While the Betka bottlebrush, crimson bottlebrush and dwarf bottlebrush occur in the same region, the three species occupy different habitats: the former grows in granite crevices in the Callistemon kenmorrisonii (Betka bottlebrush) Conservation Advice Page 1 of 7 Betka River, the second is found in moist soils or heathland (Molyneux 1995 cited in Carter & Walsh 2006), while the latter is known grow on the banks of watercourses (Harden 2002). The two known populations of the Betka bottlebrush are considered to be ‘important populations’ that are necessary for the species’ survival and recovery (Carter & Walsh 2006). Relevant Ecology Little is known about the biology/ecology of the Betka bottlebrush. In addition, given that the terrain and vegetation along the Betka River is difficult to access, no surveys have been conducted to locate other potential occurrences of the species in the region (Molyneux pers. comm., 2016). However, the species’ biology and its likely response to environmental disturbances or stimuli, such as fire, can be largely inferred from knowledge available on other Callistemon species, particularly those that have similar morphological characteristics, including the closely related dwarf bottlebrush and crimson bottlebrush (Molyneux pers. comm. 2016). The ecological requirements of the Betka bottlebrush can also be inferred from the distinct characteristics of the species’ riverine habitat (Carter & Walsh 2006; Molyneux pers. comm. 2016). The two known Betka bottlebrush populations grow in crevices in undifferentiated Silurian- Devonian granite bars which laterally underlie the Betka River and form islands in the waterway (Molyneux 1995 cited in Carter & Walsh 2006; Molyneux pers. comm. 2016). The response of the Betka bottlebrush to major changes in the flow of water down the Betka River (i.e. short-term or reduced flooding) has not been studied but recorded locations of the species and the characteristics of its riparian habitat suggest the species would be tolerant of periodic flooding at least once every 1 - 2 years (DSE 2007a and 2007b; Carter & Walsh 2006). The population located near the Stony Peak Road bridge over the Betka River occurs in riparian woodland comprised of Acacia longifolia subsp. longifolia (sallow wattle), Melaleuca squarrosa (scented paperbark), Hakea teretifolia subsp. hirsuta (dagger hakea), Epacris impressa (common heath), Pimelea linifolia (slender rice-flower), Drosera peltata subsp. auriculata (tall sundew) and Baloskion tetraphyllum subsp. tetraphyll (tassel cord-rush) (DSE 2007a). The population located at the Roger Track crossing of the Betka River occurs in riparian woodland dominated by sallow wattle, scented paperbark, Allocasuarina littoralis (black she- oak), Hakea decurrens (bushy needlewood), Lomatia myricoides (river lomatia), Kunzea ericoides spp. agg. (burgan) and Platylobium formosum (handsome flat-pea) (DSE 2007b). Like other Callistemon species, the Betka bottlebrush is probably pollinated by nectarivorous birds (honeyeaters) (Carter & Walsh 2006). The species is serotinous. Individuals store their seeds within their woody fruits for at least a year to several years until the capsule opens when it sufficiently dries out or fire triggers the capsules to open (ANBG 2016; Molyneux pers. comm. 2016). Given that the species grows in moist, occasionally inundated soils in granite crevices in the Betka River, favourable conditions for seed germination and the recruitment and growth of juveniles in a population are likely to persist after a wildfire has burned through the population (Molyneux pers. comm. 2016). The species is also a facultative resprouter. Kubiak (2009) observed that individuals of the closely related crimson bottlebrush resprouted after the 1994 wildfires in northern Sydney. In addition, individuals of another closely related species, the dwarf bottlebrush, have been known to resprout after the lower stem had been severely damaged or completely severed. This indicates that the Betka bottlebrush is likely able to survive by resprouting after similar damage through mechanical processes or being burned by fire (ANBG 2016; Molyneux pers. comm. 2016). Callistemon kenmorrisonii (Betka bottlebrush) Conservation Advice Page 2 of 7 Threats There is no information on the past distribution and abundance of the Betka bottlebrush and no evidence of any declines in existing populations. Therefore, it is not possible to determine if the species has suffered any decline in its extent of occurrence or abundance (Carter & Walsh 2006). Table 1 – Threats impacting the Betka bottlebrush in approximate order of severity of current risk, based on available evidence. Threat Threat Evidence base factor type Damage to individuals of the species Vehicle known Recreational vehicles, such as four-wheeled drives and trail bikes, movement current are active in the area and individual Betka bottlebrushes that are located where Roger Track crosses the Betka River are at risk of being damaged by vehicles (DSE 2007b). While the species is hardy and is likely to resprout after being damaged and survive (Molyneux pers. comm. 2016), damaged plants are more vulnerable to disease. Habitat loss or degradation Transport of potential The population at the Roger Track crossing of the Betka River is sediment, current threatened by the indirect effects of logging activities: the transport nutrients or of sediment, nutrients or pollutants in surface water runoff from pollutants in respective sites to sites inhabited by the Betka bottlebrush, which surface can affect the growth, recruitment and health (Carter & Walsh water runoff 2006; Molyneux pers. comm. 2016). Similarly, bridge or road works that are not effectively managed to control sediment erosion and the transport of sediment, nutrients or pollutants in surface water runoff from respective sites are a potential threat to the Stony Peak Road population (Carter & Walsh 2006; Molyneux pers. comm. 2016). Altered potential Logging of Eucalyptus species and the removal of associated hydrology current vegetation in the region may alter hydrological processes and reduce the flow of water in the Betka River (Carter & Walsh 2006; Molyneux pers. comm. 2016). A reduction in river flows may deplete the moisture content of soils in which individuals of the species are growing and increase the risk of mortality of those individuals. A reduction