Pterostylis commutata (Midland Greenhood)

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

Pterostylis commutata (Midland Greenhood)

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 1ha and extent of occurrence is 75km2. The species is known from five populations, though none of these contains more than 17 individuals. Continuing decline in the area, extent and quality of habitat, the number of populations and the number of mature individuals is projected due to ongoing agricultural activities including grazing and slashing, habitat alteration, weed invasion, and the vulnerability of small populations to stochastic disturbance events.

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

Criterion 3 - Population size and decline in numbers or distribution

The total number of mature individuals is very low, dedicated field surveys having identified a total of 42 individuals in five populations. As none of the populations contains more than 17 individuals, the population can be considered severely fragmented. As continuing decline in the area, extent and quality of habitat, the number of populations and the number of mature individuals is projected due to ongoing agricultural activities including grazing and slashing, habitat alteration, weed invasion, and the vulnerability of small populations to stochastic disturbance events, the population size and geographic distribution is precarious for the survival of the species.

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

Criterion 4 - Population size

The number of mature individuals is extremely low with the population recorded to number 42 mature individuals.

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

Criterion 5 - Probability of extinction in the wild

There is no quantitative data available against this criterion.

4. Conclusion

The species exists in extremely low numbers (42) in five severely fragmented populations. The geographic distribution, area of occupancy being 1ha and extent of occurrence, 75km2, is very restricted and precarious for the survival of the species in the face of projected declines due to ongoing agricultural activities including grazing and slashing, habitat alteration, weed invasion, and the vulnerability of small populations to stochastic disturbance events. The species is eligible for listing as critically endangered under criteria 3 and 4.

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:

Pterostylis commutata (Midland Greenhood)