Listing Statement for Barbarea australis (native wintercress) Barbarea australis

native wintercress

T A S M A N I A N T H R E A T E N E D S P E C I E S L I S T I N G S T A T E M E N T

Image by Mick Ilowski

Scientific name: Barbarea australis Hook.f., Fl. Nov.-Zel. 1: 14 (1852) Common name: native wintercress (Wapstra et al. 2005) Group: vascular plant, dicotyledon, family Brassicaceae

Status: Threatened Species Protection Act 1995: endangered Environment Protection and Biodiversity Conservation Act 1999: Endangered

Distribution: Endemic status: Endemic to Tasmania Tasmanian NRM Region: Cradle Coast, North, South

Figure 1. Distribution of Barbarea australis Plate 1. Barbarea australis growing amongst river (unconfirmed Parramatta Creek location not shown) rocks (image by Mick Ilowski)

1 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Barbarea australis (native wintercress)

IDENTIFICATION AND ECOLOGY Confusing species Barbarea australis is an annual or short-lived Three species of Barbarea occur in Tasmania, (perhaps biennial) perennial herb in the two of them, Barbarea intermedia and Barbarea Brassicaceae family, occurring along flood- verna, being introductions from the northern prone rocky river systems. Being a short-lived hemisphere. The introduced Barbarea species species, it is largely reliant on germination of can be distinguished from Barbarea australis by seed for recruitment and population their deeply-divided upper stem leaves and by persistence. It is a prolific seed producer and seeds that lack a defined edge and that are after disturbance such as flooding, hundreds of relatively rounded. seedlings can emerge in resultant gaps in winter and early spring. However, few generally DISTRIBUTION AND HABITAT survive to maturity due to browsing (mainly by native species) and disturbance by natural flood Barbarea australis is endemic to Tasmania, events. In the wild, bare ground is required for known from about 10 river systems extending recruitment. Seed is set in the first year of from northern Tasmania to rivers flowing growth. The plant can also reproduce south from the Central Highlands (Figure 1, vegetatively with a new plant growing from the Table 1). Based on extant subpopulations, the base of an existing plant (TSU 2005). Barbarea linear range of the species is about 170 km, 2 australis appears to be a poor competitor. extent of occurrence 13,045 km (Table 1), and area of occupancy 0.2 km2.

Survey techniques Barbarea australis is a riparian plant species Surveys should be conducted during the found near river margins, creek beds and along species’ peak flowering period, which is flood channels adjacent to the river. It has not November to February (Kirkpatrick & been found on steeper sections of rivers, and Gilfedder 1998). Any survey effort should be tends to favour slower reaches. It occurs in focused on potential habitat (i.e. flood-prone shallow alluvial silt deposited on rock slabs or riparian habitats). Due to the wide variation in rocky ledges, or between large cobbles on sites numbers in any one year, it is advisable that a frequently disturbed by fluvial processes. Some relatively extensive survey is undertaken at any of the sites are a considerable distance from the site because the species can be spread over river in flood channels scoured by previous several kilometres of river system, and may flood action, exposing river pebbles. One site shift from site to site between years, dependent observed was on bare soil at the base of a cliff on disturbance conditions. approximately 40 m from the river and 3 to 4 m above a secondary stream. There was little Description apparent influence of water at the site but active soil movement kept the site bare and Barbarea australis is an erect plant up to 50 to 100 cm high. The lower stem leaves are 8 to 10 moisture seeping from the base of the cliff kept cm long and form a rosette or radiating cluster. it moist. The sites range in altitude from 260 to The leaves are stalked, broader at the ends and 700 m on alluvial silt overlying a number of develop 2 to 3 small lateral lobes on the leaf rock types including dolerite, basalt and granite. stalk below the main part of the leaf. The leaves A number of the localities are associated with on the upper stem are simple with wavy watercourses along contact zones between margins. The flowers are yellow, the petals 2 to Permian mudstone and either dolerite or basalt. 8 mm long. The many seed capsules or pods Barbarea australis is found at the margins of are 20 to 40 mm long and 2 to 2.5 mm wide. riverine scrub with Leptospermum lanigerum, The seeds are broad and oval, 1.5 mm long and Dodonaea viscosa and Pomaderris species in forest have irregular edges or narrow wings. communities dominated by Eucalyptus [description from Hooker 1859, Curtis 1956, delegatensis, E. dalrympleana, E. pauciflora and Hewson 1982] E. ovata. Adjacent sites often consist of tussock grassland or grassy woodland dominated by Poa 2 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Barbarea australis (native wintercress) labillardierei or Themeda triandra. At most sites it RESERVATION STATUS grows in open rocky situations with little Barbarea australis is reserved within Mole Creek competition from other plant species, although Karst National Park, Mersey River Forest at some localities it grows amongst large Poa Reserve, Hellyer Gorge State Reserve and tussocks in relatively dense vegetation. North Esk Forest Reserve. Protection to some subpopulations is also afforded by their POPULATION ESTIMATE occurrence in Crown river reserves (e.g. parts Total population size is estimated to be about of the St Patricks River subpopulations) or in 900 mature individuals (Table 1; TSU 2005). As informal reserves under Forestry Tasmania’s the species is short lived and recruitment is Management Decision Classification mapping largely by seed, particularly following system (Orr & Gerrand 1998). disturbance, numbers of individuals in subpopulations can fluctuate widely from year CONSERVATION STATUS to year though subpopulation sizes are typically Barbarea australis was listed in 1995 as no more than 50 mature individuals and often a endangered on the Tasmanian Threatened Species lot smaller. Estimates in Table 1 are counts of Protection Act 1995, meeting criterion C: total mature individuals from subpopulations when population estimated to number fewer than last seen. The largest subpopulation yet 2,500 mature individuals, specifically criterion recorded had 135 mature individuals C2. a continuing decline, observed, projected, (St Patricks River), while other subpopulations or inferred, in numbers of mature individuals with over 100 mature individuals are known and population structure in the form of either: from the River Ouse near Waddamana, the a.(i). severely fragmented (i.e. no subpopulation River Clyde and the Nive River (Table 1). The estimated to contain more than 250 mature number of subpopulations is also likely to individuals); and b. extreme fluctuations in the fluctuate as local extinctions occur due to number of mature individuals. It also meets increased risks associated with small criterion D: total population very small or area populations (TSU 2005). of occupancy restricted, specifically D1. total population estimated to number fewer than It is likely that Barbarea australis has always been 1,000 mature individuals. relatively locally uncommon. Barbarea australis was presumed extinct until rediscovered in the THREATS, LIMITING FACTORS AND 1980s, having not been collected since the MANAGEMENT ISSUES 1830s from northwest Tasmania. However, the Barbarea australis is at risk because most close similarity of Barbarea australis with subpopulations are on private land and are at introduced Barbarea species may have caused risk from habitat loss and modification, the species to be overlooked by collectors. increased grazing pressure and stochastic events Since 2000, only two additional subpopulations as follows. have been located. Of these, the Hellyer River site is a significant extension of the extant range Habitat loss and modification: Barbarea into the State’s far northwest. While there is australis has suffered significant loss of potential considerable potential habitat within the habitat since European settlement (TSU 2005). species’ current known range, formal and This was largely due to land clearance through informal surveys have failed to locate further early exploitation of accessible and relatively subpopulations. fertile areas including riparian ecosystems for agricultural purposes. It should be noted that It is unlikely that the recording of additional much of the habitat of the species is ‘Riparian subpopulations will alter the estimates of total scrub’, a threatened vegetation community population numbers by orders of magnitude listed under Nature Conservation Act 2002. because all known subpopulations tend to be of relatively low numbers (usually less than 100).

3 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Barbarea australis (native wintercress)

Table 1. Population summary for Barbarea australis

Subpopulation Tenure NRM 1:25 000 Year last Area of Number of region mapsheet (first) seen occupancy plants (ha) 1 River Clyde private land South Dennistoun 1999 0.0003 3 (seedlings) (north of Bothwell) 2 River Clyde private land South Cawood 2007 0.011 111 (south of Falls of (1994) Clyde) 3 River Derwent State forest, South Wayatinah 2000 0.0001 1 (north of Hydro Tasmania Wayatinah Dam) 4 River Derwent State forest, South Wayatinah 2001 0.001 2 (north of Hydro Tasmania Wayatinah Dam) 5 Mersey River Mersey River South Liena 2002 0.006 (along 63 (1999) (south of Lake Forest Reserve, (1997) 2.8 km of Parangana) Mole Creek Karst river) National Park 6 Micks Creek private land South Penny 1999 0.002 20 (Silver Plains) (1984) 7 Nive River private, South D’Arcys 1999 0.0003 3 (Clarence Hydro Tasmania Pipeline north of Liapootah Dam) 8 Nive River Wentworth Creek South D’Arcys 1999 0.01 (over > 1 104 (west of Bradys Forest Reserve, (1996) km of river Lake) private land length) 9 Nive River State Forest, South Wayatinah, 2005 0.004 (over 3.5 50 (in 2001) (south of Hydro Tasmania Tarraleah (1999) km of river) Liapootah Dam) 10 North Esk North Esk Forest North Ben Nevis 2000 0.0002 2 River Reserve (north of Blessington) 11 River Ouse private land South Waddamana 1999 0.01 104 (north of Waddamana) 12 River Ouse private land, South Waddamana 2005 0.002 23 (2001) (Waddamana) Crown land (1982) 13 River Ouse private land South Waddamana 1984 (south of 2002 0.0005 (2002) 60 (2002) 2009 6 (2009) Waddamana) 14 River Ouse private land South Cluny 2002 0.005 50 (near Shannon (1984) River) 15 River Ouse private land South Hermitage 2002 0.0025 100 (northwest of (1984) Carrot Hill) 16 Shannon River private land South Hermitage 2002 0.0045 seedlings (near Blackburn (2001) Creek) 17 Shannon River private land South Cluny 2002 0.005 50 (1991) (near Ouse (1984) River)

4 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Barbarea australis (native wintercress)

Subpopulation Tenure NRM 1:25 000 Year last Area of Number of region mapsheet (first) seen occupancy plants (ha) 18 Clarence River Hydro Tasmania South D’Arcys 1986 unknown unknown (near Nive River) 19 St Patricks river reserve, North Patersonia 2000 0.0016 16* River private land (Diddleum Plains) 20 St Patricks river reserve North Maurice 2000 unknown unknown River (Diddleum Plains) 21 St Patricks State forest North Patersonia 2000 0.0001 1 River (Corkerys Road) 22 St Patricks private land North Maurice 2004 unknown 135 River (upper reaches) 23 Hellyer River river reserve near Cradle Parrawe 2002 0.0001 1 Hellyer Gorge Coast State Reserve 241 Parramatta State forest Cradle Railton 2004 unknown unknown Creek Coast 252 Hampshire Private land Cradle unknown 1837 presumed extinct Hills Coast 263 Woolnorth Private land Cradle unknown 1835 presumed extinct Coast *numbers boosted to 100s at times by redistributing seed in situ though numbers are curtailed by browsing (Chris Calverly, pers. comm.); 1 identity requires confirmation; 2 possibly same as subpopulation 23; 3 location marked as ‘W’ on specimen presumed to be Woolnorth

Habitat loss has also occurred through invasion reduction in the creation of bare ground of exotics, mainly gorse (Ulex europaeus) and favoured for recruitment. In the longer term, willows (Salix species) which exclude other damming will also lead to a reduction in silt vegetation. Willows significantly modify river levels below the dam walls, thereby reducing channels. The presence of willow and dams recruitment niches. This is becoming apparent upstream of occurrences affect flow regimes, below dams on the Mersey, Ouse and Shannon which may impact on seed dispersal as well as rivers. availability of suitable habitat for recruitment. Grazing pressure: As a member of the Willow removal may have adverse impacts due Brassicaceae family, Barbarea australis is palatable to the bank disturbance and channel to animals, including native mammals, domestic modification that occurs following removal. stock, rabbits, snails and insects. Even though Habitat loss is an ongoing threat, particularly as hundreds of seedlings may emerge following most occurrences are on private land. disturbance, if grazing pressure is high, the Impoundment construction: Many of the plants may not survive long enough for seed set upper reaches of the rivers where Barbarea to be achieved. At some sites, established plants australis occurs have been dammed for are so heavily browsed that seed set is electricity production and irrigation schemes. prevented, even though the plants themselves Dams, along with effects of willows on flow may survive. As well as the grazing pressure regimes, may have an adverse impact on seed from introduced animals and stock, as more dispersal and availability of suitable habitat for pasture has been created, the numbers of native recruitment, particularly if the frequency and browsers have also increased (TSU 2005). intensity of flooding is reduced leading to a Grazing pressure is different for each

5 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Barbarea australis (native wintercress) subpopulation, being dependent on whether authorities controlling areas that support native and/or domestic browsers are present. Barbarea australis; Grazing pressure is highest for subpopulations surveying numerous rivers to determine the on private property that allow domestic stock species’ presence and condition of to access riparian areas (e.g. subpopulations on subpopulations; the Ouse and Clyde rivers). signing a management agreement with one Forestry activities: Forest clearing is a landowner; potential threat to unreserved sites, either directly from physical impacts of operations or establishing plants as seed orchards for seed indirectly via alterations to flow regimes of input into the wild at one site; adjacent rivers and streams. However, there are reducing grazing pressure on individuals at regulatory and policy mechanisms in place some sites by placing tree branches over within the Forest Practices system to ensure plants; that known subpopulations of threatened flora are managed in wood production forests collecting seed in situ and manually (Forest Practices Board 2000). dispersing to several nearby sites along the St Patricks River, successfully increasing the Stochastic risk: Numbers of individuals within size of the subpopulation; subpopulations can fluctuate widely from year to year. Typically there are fewer than 50 collecting seed for long term conservation mature individuals in a subpopulation, often storage at the Tasmanian Seed much fewer. Such small subpopulations have Conservation Centre; an increased risk of becoming extinct through The current Recovery Plan for Barbarea australis chance events. Due to the widespread (TSS 2005) is being updated. distribution of the species, the risk of stochastic extinction is low at a State-wide level, but may be higher at the level of subpopulation. Management objectives Translocating nursery grown plants to increase The overall objective for the management of subpopulation size to reduce stochastic risk is Barbarea australis is to reduce the extinction risk problematic due to difficulties associated with to the species by protecting known caging or fencing on river edges, and risk of subpopulations, increasing plant numbers and introducing insect pests such as root aphids. managing subpopulations and habitat. Dispersal of seed into suitable gaps may be more suitable though, if nursery produced, What is needed? there is a risk that brassica seed-borne bacterial disease will be introduced to the wild. boost numbers in subpopulations by encouraging seed production in situ and MANAGEMENT STRATEGY distributing seed into suitable recruitment niches, monitoring seed germination What has been done? success, and protecting seedlings from grazing through fencing and brush Recovery actions undertaken during coverings; implementation of previous Recovery Plans for Barbarea australis (Potts & Gilfedder 2000, TSU identify and map potential habitat and 2005) have included: conduct follow-up surveys of potential habitat; monitoring transects along a number of significant rivers (Ouse, Nive, Mersey verify reports of any new occurrences of rivers) to assess subpopulation fluctuation Barbarea australis; over time; control willows (where feasible), control preparing and distributing management gorse in subpopulations threatened by that prescriptions and a decision-making weed, and prevent the invasion or further support manual for land managers and 6 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment

Listing Statement for Barbarea australis (native wintercress)

invasion by willows and other woody weeds George, editor). Australian Government in all subpopulations; Publishing Service, Canberra. manage environmental flows to allow the Hooker, J.D. (1852). The botany of the Antarctic persistence of the species; voyage of H.M. discovery ships Erebus and Terror. II. Flora Novae-Zelandiae 1(1): 14. periodically monitor selected subpopulations and surrounding habitat Hooker, J.D. (1859). Flora Tasmaniae (Botany of during the flowering period to identify the Antarctic voyage: volume 3). Lovell Reeve, threats as well as conditions that promote London. recruitment, better understand the Kirkpatrick, J.B. & Gilfedder, L. (1998). dynamics of subpopulations, determine the Conserving weedy natives: two Tasmanian impacts of grazing and other disturbance, endangered herbs in the Brassicaceae. gauge the success of management actions, Australian Journal of Ecology 23:466–473. and determine whether management Orr, S. & Gerrand, A.M. (1998). Management intervention is required; decision classification: A system for zoning support the Private Land Conservation land managed by Forestry Tasmania. Program (DPIPWE) with the establishment Tasforests 10: 1 14. of conservation covenants for private land Potts, W.C. & Gilfedder, L. (2000). Barbarea supporting the species, and ensure that australis Recovery Plan. Department of current priorities for the species are Primary Industries, Water and Environment, incorporated into the program’s reservation Hobart. strategies; TSU (Threatened Species Unit) (2005). Native provide information and extension support wintercress, Barbarea australis Flora Recovery to relevant Natural Resource Management Plan 2005-2009. Department of Primary committees, local councils, government Industries, Water and Environment, Hobart. agencies, the local community and Wapstra, H., Wapstra, A., Wapstra, M. & development proponents on the locality, Gilfedder, L. (2005). The Little Book of significance and management of known Common Names for Tasmanian Plants. subpopulations and potential habitat. Department of Primary Industries, Water and Environment, Hobart. BIBLIOGRAPHY Curtis, W.M. (1956). The Student’s Flora of Prepared in September 2000 under the Tasmania Part 1. Gymnospermae Angiospermae: provisions of the Tasmanian Threatened Species Ranunculaceae to Myrtaceae. Government Protection Act 1995. This revision prepared in Printer, Hobart. June 2010 and published in November 2010. (National status updated in January 2014.) Forest Practices Board (2000). Forest Practices Code 2000. Forest Practices Board, Hobart, Cite as: Threatened Species Section (2010). Tasmania. Listing Statement for Barbarea australis (native wintercress). Department of Primary Industries, Gilfedder, L. (1994). Barbarea australis Flora Parks, Water and Environment, Tasmania. Recovery Plan: Management Phase. Wildlife Report 94/4, Parks and Wildlife Service, View: Tasmania. www.dpipwe.tas.gov.au/threatenedspecieslists Harris, S. & Kitchener, A. (editors) (2005). From Contact details: Threatened Species Section, Forest to Fjaeldmark: Descriptions of Tasmania’s Department of Primary Industries, Parks, Vegetation. Department of Primary Water and Environment, GPO Box 44, Hobart, Industries, Water and Environment, Hobart. Tasmania, Australia, 7001. Phone (03) 6233 6556; fax (03) 6233 3477. Hewson, H.J. (1982). Brassicaceae. In: Flora of Permit: It is an offence to collect, disturb, Australia Vol 8 Lecythidales to Batales (A.S. damage or destroy this species unless under permit. 7 Threatened Species Section – Department of Primary Industries, Parks, Water and Environment