Barbarea australis (Native Wintercress)

Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the list of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)

1. Scientific name, common name (where appropriate), major taxon group

Barbarea australis (Native Wintercress)

2. National Context

The species is endemic to Tasmania. The species is currently listed as endangered under the EPBC Act and the Tasmanian Threatened Species Protection Act 1995.

3. How judged by TSSC in relation to the EPBC Act criteria.

TSSC judges the species to be eligible for listing as critically endangered under the EPBC Act. The justification against the criteria is as follows:

Criterion 1 - Decline in numbers

There is no quantitative data available against this criterion.

Criterion 2 - Geographic distribution

The geographic distribution of the species is precarious for the survival of the species and is restricted. The area of occupancy is 0.2ha. The species is considered to be subject to extreme fluctuations in the number of mature individuals due to its annual or biennial lifecycle with high seed production and germination but varied survival rates. Continuing decline in the area, extent and quality of habitat, the number of populations and the number of mature individuals is projected due to grazing, agriculture and loss of habitat to weed species.

Therefore, the species is eligible for listing as critically endangered under this criterion.

Criterion 3 - Population size and decline in numbers or distribution

The total number of mature individuals is low, there being a total of 500 mature individuals in eight populations, the largest recorded to contain 111 individuals. The populations are, however, not considered to be severerly fragmented and the rate of decline has not been quantified.

Therefore, the species is not eligible for listing under this criterion.

Criterion 4 - Population size

The number of mature individuals is very low with the total population recorded to number 500 mature individuals.

Therefore, the species is eligible for listing as vulnerable under this criterion.

Criterion 5 - Probability of extinction in the wild

There is no quantitative data available against this criterion.

4. Conclusion

The geographic distribution, area of occupancy, 0.2ha, is precarious for the survival of the species. The species is subject to extreme fluctuations in population size due to the species annual or biennial life cycle with high seed production and germination but varied survival rates. There are ongoing projected declines in the area, extent and quality of habitat, the number of populations and the number of mature individuals due to grazing, agriculture and loss of habitat to weed species. The species is eligible for listing as critically endangered under criterion 2.

5. Recommendation

TSSC recommends that the list referred to in section 178 of the EPBC Act be amended by
transferring from the endangered category to the critically endangered category:

Barbarea australis (Native Wintercress)