Strategic Management Prospects v4.0 Species Forecast Report created on 05 February, 2024

A Species Forecast Report is a summary of currently available information, the predicted 50-year outlook for the species, and potential pathways to recovery through species-specific and landscape-scale actions.

The report collates data from a range of sources including the Victorian Biodiversity Atlas, Strategic Management Prospects (SMP), Specific Needs Assessments, Threatened Species Action Statements, the Genetic Risk Index, and the IUCN Common Assessment Method.

Species Forecast Reports are intended to be used in conjunction with SMP and other spatial outputs in NatureKit, and Action Statements where relevant.

For more information on Species Forecast Reports, SMP and other biodiversity decision support tools, including user guides, visit Choosing actions for nature webpage on the DEECA website.


Species Overview

Taxon ID 503389
Scientific name Thesium australe
Common name Austral Toad-flax
Group Dicotyledons
FFG status Endangered
EPBC status Vulnerable
Austral Toad-flax (Image Source: Atlas of Living Australia)

Austral Toad-flax (Image Source: Atlas of Living Australia)


Species description

Description and life history

The taxon is a perennial herb (but stems mostly annual from woody rootstock) to c. 40 cm high, glabrous, pale green or yellow-green; stems 1-several, little-branched, wiry, striate. Leaves alternate, linear, mostly 1-4 cm long, 0.5-1.5 mm wide, rather lax, acute, midrib decurrent, margins entire, sessile; lowest leaves scale-like. Inflorescences axillary; peduncle 1-3 mm long, united with leaf-base; bracteoles 2, opposite, linear, mostly 2-5 mm long, inserted on leaf 1-3 mm above axis; pedicel very short. Receptacle cupular-globose, c. 1 mm long; tepals oblong, c. 1.5 mm long, united at base, finely keeled, tips incurved, green with white margins; stamens inserted c. halfway on tepals; style c. 1 mm long, stigma globular. Fruit globose, c. 2 mm diam., reticulate-striate. Flowers mostly spring and summer (VicFlora 2019). The taxon is semi-parasitic on roots of grassland species (Leigh et al., 1984 2 cited in DSE 2003), notably kangaroo grass (Themeda australis) (Scarlett et al., 2003 2 cited in DSE 2003). The dispersal mechanism is suspected to be wind, the distance suspected to be insubstantial in view of the very small flowers (Arn Tolsma, pers. comm.).

Distribution

The taxon was once widespread across Victoria, but all recent collections are from highland areas in the vicinity of Wulgulmerang and it is believed to have become extinct across most of its Australian range due to loss of habitat and grazing (VicFlora 2019). Despite to extensive searches by botanists from La Trobe University, Austral Toad-flax has been found at only five sites in Victoria since 1979. All sites are confined to areas between 800 m2 and 24 ha. The localities for two relatively recent, unconfirmed collections from Second Emu Plain and Racecourse Paddock on ‘Rockbank’ property, have not been searched; these records were not known to La Trobe University before 1990. It is possible that the ‘Racecourse Paddock’ record is the same locality as A.C. Beauglehole’s ‘Mt Hamilton’ record. The Lake King Area (W50) was not specifically searched, but Austral Toad-flax was not found on the Gippsland Plains, during searches for other species in grassland remnants between 1979 and 1984.

Habitat

The taxon grows in grasslands, woodlands and herbfields, usually in damp situations (VicFlora 2019). The taxon has a wide ecological tolerance having been recorded from subtropical, temperate and sub-alpine climates, and on soils derived from sedimentary, igneous and metamorphic rocks as well as recent alluvium. However, it is largely confined to grasslands, grassy woodlands or sub-alpine grassy heathlands. Whilst the taxon is usually associated with Kangaroo Grass and (less frequently) with Poa spp., it will grow with other hosts, at least in the glasshouse.

Genetic Risk Index

This table contains information on the genetic health of Austral Toad-flax, informed by recent work conducted by Monash University and cesar Pty Ltd (Kriesner et al. 2019; Kriesner and Weeks 2020). The project undertook genetic risk assessments of ~1,100 species of flora and fauna found in Victoria and generated a large database of available genetic and demographic data for these species. A framework was developed for combining these parameters into a Genetic Risk Index that classified species broadly into ‘Low’, ‘Moderate’, ‘High’, ‘Very High’ and ‘Uncertain’ risk categories. The Genetic Risk Index will continue to undergo refinement and validation to provide further insight into the genetic health of species in Victoria.

Total Australian population size 2,000 - 10,000 individuals
Australian distribution Most of the population occurs outside of Victoria
Dispersal capacity Medium: ~10km
Reproductive mode Sexual: species reproduces sexually via male and female gametes
Average generation time Perennial: longer-lived than annuals, but further estimate is not readily available
Victorian population trend since ~1975 Population has significantly decreased
Inbreeding evidence Not assessed
Genetic diversity Not assessed
Genetic rescue potential High: at least some populations are at high risk of decline or extinction without genetic intervention
Genetic Risk Index High


Species maps

Habitat Distribution Model

The Habitat Distribution Model (HDM) layer shows the modelled distribution of habitat for Austral Toad-flax in Victoria. Red shading indicates areas of habitat with relatively higher suitability, compared with yellow shaded areas. HDMs are developed by combining Victorian Biodiversity Atlas (VBA) occurrence records for the species with a range of environmental variables to predict where the most suitable habitat for the species is in Victoria. Species may not always occupy areas of suitable habitat. Threatening processes (prior or ongoing) and disturbance regimes (e.g. fire, timber harvesting) may stop species from occupying otherwise suitable habitat for periods of time. Management actions often focus on currently occupied areas, however management of unoccupied areas can also be important to allow populations to re-establish.

No Habitat Distrabution Model is currently available.


Species Forecast

No Species Forecast data is available because Austral Toad-flax is not yet included in our decision-support tools.

About Species Forecast

A Species Forecast is the estimated likelihood of a species being present in 50 years time. The data for Species Forecasts is drawn from DEECA’s decision support tools, Strategic Management Prospects and Specific Needs Assessments.

Many species benefit from the management of widespread threats, such as weeds and pests, and the benefit of these landscape-scale actions to ~4,200 species is modelled in Strategic Management Prospects. In addition to landscape-scale actions, some species also need actions that improve or protect habitat at certain sites, such as nest boxes or hollow logs, or actions to improve certain populations, such as gene mixing or translocation.

As part of a continuous improvement program for our decision-support tools, we are working to expand the scope of actions modelled in Strategic Management Prospects, and to build the dataset of species benefits from location-specific and population-specific actions.

We can use this data to consider how different actions may benefit a species and examine how different types of on-ground management may contribute to a species’ recovery in 50 years, to develop a Species Forecast.


Potential actions for species recovery

No Species Forecast data is available because Austral Toad-flax is not yet included in our decision-support tools.


Species prospects in SMP

The benefit data in SMP can be used to consider what the Austral Toad-flax’s prospects are if the landscape scale management actions in SMP are implemented.

No Species Prospects figure is available becuase Austral Toad-flax is not yet included in SMP.


How to get further information and provide feedback

For more information on the decision support tools, products and underlying data used in this report, and how the data is collected and developed into products, please visit the following links:

These links include information on how to provide data and feedback into these products.

The Species Forecast Reports will be updated periodically to reflect changes and improvements in the products and tools that inform them (e.g., following updates to SMP).

As the data contained in Species Forecast Reports is drawn from multi-species datasets, it is not currently possible to incorporate species-specific information or feedback directly.

For help or further information get in touch by visiting Choosing actions for nature webpage on the DEECA website.


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