THREATENED SPECIES SCIENTIFIC COMMITTEE Established under the Environment Protection and Biodiversity Conservation Act 1999 The Minister’s delegate approved this Conservation Advice on 01/04/2016. Conservation Advice Grevillea wilkinsonii Tumut grevillea Conservation Status Grevillea wilkinsonii (Tumut grevillea) is listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth) (EPBC Act). The species is eligible for listing as prior to the commencement of the EPBC Act, it was listed as Endangered under Schedule 1 of the Endangered Species Protection Act 1992 (Cwlth). The main factors that are the cause of the species being eligible for listing in the Endangered category are its restricted geographic distribution and small population size, with ongoing threats. Grevillea wilkinsonii is listed as Endangered under the NSW Threatened Species Conservation Act 1995. Description The Tumut grevillea is an ascending to erect shrub when young, becoming denser and more spreading with age or when growing under a dense canopy. The species grows to 2 m tall and wide or, rarely, sprawling to 4 m wide. The flowers are purple-pink, with a lilac-pink style with a pale yellow tip (Makinson 1993, 2000; NSW NPWS 2001; Olde & Marriott 1995). The Tumut Grevillea occurs in two disjunct populations and, although clearly of the same species, the upstream 'Goobarragandra' and the downstream 'Lacmalac' populations show differences in certain morphological characteristics, which are probably genetically fixed. The most obvious differences between the two populations are leaf length (8–12.5 cm in the Goobarragandra population, as against 9.5–17 cm in the Lacmalac population); number of serrations (5–11 teeth per side as against 13–15 per side); and leaf-serration size (up to 2 mm length as against up to 4 mm) (Makinson 1993). The most distinctive features of the Tumut grevillea, as compared with its close south-eastern Australian relatives, are the oblong-shaped leaves with regular, small serrations on the margins and the small lilac-pink flowers in toothbrush-like heads. It may be confused with G. longifolia and is distantly related to G. sericea, a native of the Hawkesbury sandstones around Sydney with similar coloured flowers (Briggs & Wright 1998; NSW NPWS 2001). G. longifolia has longer leaves of 7–22 cm (compared to 5–17 cm in the Tumut grevillea), longer pistils of 21–24 mm (compared to 14–15 mm long for the Tumut grevillea) and erect conflorescences (deflexed or decurved in the Tumut grevillea) (Olde & Marriott 1995; NSW NPWS 1999). Distribution The Tumut grevillea occurs primarily in south-east NSW where it is restricted to a 20 km stretch of the Goobarragandra River, 18 km south-east of Tumut (Briggs & Wright 1998; Makinson 2000). There is also a small colony of approximately seven plants known to occur near Gundagai (Taws 2011). The species was discovered in 1982, described in 1993 and initial surveys were carried out in this period to measure the size and structure of the population (Taws 2011). A survey was carried out in 1998 to assess the total population size. Planting of tubestock under agreements with private landholders was carried out as an identified recovery action after the 1998 survey. Grevillea wilkinsonii (Tumut grevillea) Conservation Advice Page 1 of 7 The small colony near Gundagai was found shortly after the 1998 survey. The total population was again measured in 2008 surveys (Taws 2011). It appears that within the known distribution, the original population suffered some fragmentation, primarily due to land clearing and grazing by domestic stock. Nine small sections of riparian habitat along the Goobarragandra River supported the Tumut Grevillea. In 2001, seven sites supported 80% of the population occurred on private freehold land. The remaining two sites are on Crown Land. The private land close to the populations on the riverbank has been extensively cleared and is used for stock grazing. The Crown Land sites are largely uncleared but have been accessible to domestic stock in the past (Briggs & Wright 1998; NSW NPWS 2001). A survey undertaken in 2008 found that the total 'natural' Tumut grevillea population was 514 individuals, with 56% adults. Including the planted individuals, the population was estimated to be 805 (Taws 2011). Populations are characterised by the presence of a wide range of size classes, indicating that recruitment is reasonably frequent (Briggs & Wright 1998; NSW NPWS 2001). Relevant Biology/Ecology The Tumut grevillea grows on river banks and nearby slopes in rocky, loamy soils over granitic and ultrabasic substrates (Makinson 2000). It occurs in alluvial pockets and crevices on granodiorite and serpentinite at two sites, and alluvial and sandy soils at another site on coarse grained granitic rock. All other sites are on ultrabasic rock types (such as basalt), which occur along the middle reaches of the Goobarragandra River between Lacmalac and Goobarragandra. Habitat for the species is between 310 m and 340 m asl. Most individuals grow close to the edge of the river, well within the flood zone, and a few occur up to 40 m from the river, well outside the flood zone. At all sites the native vegetation includes remnant, riverine shrub communities adjacent to open-forest. The most common tree species in these communities are Eucalyptus blakelyi, E. macrorhyncha, E. bridgesiana and E. melliodora. Brachychiton populneus grows in nearby paddocks. Taller shrubs of the lower slopes and riverbanks include Acacia melanoxylon, A. pravissima, Bursaria lasiophylla, Callistemon sieberi, Dodonaea viscosa subsp. spatulata, Hakea macrocarpa, Kunzea ericoides, Leptospermum brevipes, L. obovatum, Lomatia myricoides, Pomaderris angustifolia and Xanthorrhoea glauca subsp. angustifolia. Smaller shrubs include Calytrix tetragona, Correa reflexa, Crowea exalata and Grevillea lanigera (Briggs & Wright 1998; NSW NPWS 2001). Flowering of the Tumut grevillea is prolific between October and November, which is considered to be an unusually narrow flowering period for a Grevillea species. However, a weak second flowering period often occurs in autumn (Makinson 1993, 2000). The fruit produced following the main flowering event matures during December and early January and dehisces to release one seed (sometimes two) (Briggs & Wright 1998; NSW National Parks & Wildlife Service 2001). The rate of fruit set is high, though there also appears to be a fairly high predation of the ripening fruits and fallen seed. Ants may have a role in seed dispersal, as in one instance numerous seedlings were found emerging from an ant's nest (Butler & Makinson 1993). Most species in the 'toothbrush-flowered' group of grevilleas are adapted to bird pollination, but the Tumut grevillea has small flowers and they are believed to be insect pollinated. Native bees and ants have been collected from flowering plants, and a variety of flies, beetles and introduced honey bees have been noted as visitors. The flower has a strong and rather unpleasant perfume, not unlike the smell of mice (Makinson 1993; Briggs & Wright 1998; NSW NPWS 2001). Individual growth rates and longevity have not been monitored in the field, but the growth rates of cultivated plants have been moderate and some individuals have been known to survive for at least 15 years. It is thought that individuals probably live up to 30 years in the wild. All known sites contain individuals of varying ages. Numerous seedlings have been observed at some sites in the wild, and seedlings have also been observed to become established under planted Grevillea wilkinsonii (Tumut grevillea) Conservation Advice Page 2 of 7 trees. Most healthy, adult plants occur in open areas and the species thus seems to prefer full sun to partial shade and is rarely found under the canopy of dense vegetation. It is to be noted that Gleeson (1994) found the species capable of inbreeding and outbreeding (Briggs & Wright 1998; NSW NPWS 2001). The response of the Tumut grevillea to fire is not well known. Observations of an ex situ population at the Tumut Ecological Reserve Trust Reserve in early December 1998 noted the death of adult plants and the subsequent germination of seedlings after a low intensity wildfire. Closely related Grevillea species are known to be fire sensitive and function as obligate seeders (produce a seed bank which responds to fire). Such species can be threatened by burning at too frequent intervals. In addition, field observations of the Tumut grevillea have found only limited resprouting from stem bases and no signs of resprouting from lignotubers or root suckers after physical damage to adult plants. Numerous seedlings of this species have established in the absence of fire, both in natural populations and near cultivated plants, indicating that recruitment is not fire dependent, but may be improved by fire (Briggs & Wright 1998; NSW NPWS 2001). Threats Table 1 – Threats Threat factor Threat Threat Evidence base type status Invasive species Weeds known current Two highly invasive, introduced weed species, blackberry (Rubus fruticosus complex) and willow (Salix sp.) occur at several Tumut grevillea sites. Blackberry poses the most immediate threat, as large patches have colonised the river bank in parts of Tumut grevillea habitat. Uncontrolled blackberry plants will smother and kill adult Tumut grevillea plants and prevent seedling establishment. Willows, if uncontrolled, are likely to increase in density along the river banks and create high levels of shading believed to also be unfavourable for the survival of the Tumut grevillea. Other weed species that are present at some sites and may need future management include paspalum (Paspalum dilatatum), phalaris (Phalaris aquatica), briar rose (Rosa rubiginosa), purple top (Verbena sp.) and wildling fruit trees (Malus spp. and Prunus spp.) (Briggs & Wright 1998; NSW NPWS 2001). Impacts of domestic species Grazing known current Seven of the nine natural subpopulations of the Tumut grevillea along the Goobarragandra River occur on private land and are subject to varying degrees of grazing damage and habitat degradation by stock, particularly cattle.