Threatened species & ecological communities

Carmona (Carmona retusa)

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)
15 September 2005

Contents

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

Carmona retusa (Carmona), a plant.

Previously known as Ehretia microphylla.

2. Description

A much-branched tall shrub to small tree, 1-4+ m tall that is deciduous or semi-deciduous during the dry season. It has moderately small leaves with small white flowers and small fruit.

On Cape York Peninsula, Carmona is recorded from vine thickets or scrubs on dry rocky hills, in habitat best described as semi-evergreen vine thickets. On Christmas Island, Carmona appears to favour dry sites on the terraces, and all of the terraces are potential habitat. It is recorded as being a frequent component of open, scrubby and vine forests, and an occasional component of primary (plateau) rainforest and marginal (terrace) rainforest (Butz 2004).

3. National context

Carmona is a widespread plant, occurring in southern Asia from India to Taiwan and the Philippines, and in New Guinea, northern Australia and the Solomon Islands. In Australia, it occurs on Christmas Island and Cape York Peninsula, northern Queensland. It is likely that its occurrence on the Australian mainland is a relict from the period when the Peninsula area was linked by land to New Guinea, where the species is also found. It was introduced and naturalised in Hawaii, where it is considered to be an invasive plant (Butz 2004).

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

TSSC judges the species to be not eligible for listing under the EPBC Act. The justification against the criteria is as follows:

Criterion 1 - Decline in numbers

On Christmas Island, Carmona is considered to be common and widespread on all the different types of terraces, and found in reasonably high densities with numerous populations. It is also occasionally found in plateau rainforest (Butz 2004). There do not appear to be any island-wide surveys for this species, though there have been localised surveys as part of environmental assessments. Large areas of the terraces and most of the plateau rainforest occur within Christmas Island National Park.

On Cape York Peninsula, the only part of mainland Australia where Carmona is recorded, Carmona has a naturally disjunct distribution. A recent rare and threatened plant project on Cape York Peninsula has surveyed for this species, and it was recorded from eight localities which include northern, central and southern areas of the Cape York bioregion (as described by Sattler & Williams 1999), indicating a linear range of approximately 630 km (Butz 2004). These localities are:

The exact population numbers at the localities are not known, but general comments on numbers include that it is rare to common at Mount White near Coen, frequent at Birthday Mountain in Mungkan Kandju National Park, and occasional at Ambition Scrub in Lakefield National Park (Butz 2004).

Although there are potential threatening processes that could be operating in the general areas where this species occurs on both Christmas Island and Cape York Peninsula, no populations of the species are known to be under any particular threat.

On Christmas Island, the removal of Carmona habitat or individuals by phosphate mining, construction of roads or other developments may occur in the future, however, Carmona is widespread and common, with large areas of suitable habitat found within the Christmas Island National Park. It is unlikely that developments will threaten Carmona in the future. There are other known threats impacting on Christmas Island but none are known to be impacting on this species.

On Cape York Peninsula, there are no known or likely future threats to the species (Butz 2004). Much of Cape York Peninsula remains undeveloped with minimal infrastructure, and often only localised development impact. Land clearing, which may damage and remove Carmona and its habitat, has been identified as a potential threat, however, the dry rocky hills favoured by Carmona are not generally favourable for grazing or agricultural development and this habitat faces little or no threat from grazing animals (Butz 2004).

Another potential threat to the species is the changed fire-regimes associated with grazing management on Cape York, but the dry rocky hills favoured by Carmona do not appear to be adversely impacted by this. The dense vegetation where this species occurs inhibits grass encroachment, limiting the availability of fuel and providing a degree of natural self-protection from fire (Butz 2004).

Introduced species such as pigs, horses, cane toads, and cats are distributed throughout Cape York Peninsula (Butz 2004). However, no feral animal species have been identified as posing any threat to Carmona. The dry rocky hills that provide its habitat are not favoured by many feral animals (J. Landsberg, pers. comm.). Carmona is not threatened by weeds to any great degree as few of the dry scrubs in the region which it inhabits are severely affected by weed invasion (Butz 2004).

Carmona is widespread and common on Christmas Island and has a naturally disjunct distribution on Cape York Peninsula, occurring at eight locations on the Peninsula. Although there are a number of threats that operate in the general areas where this species occurs, there does not appear to be any threats operating on Carmona that are affecting its long-term survival. Current evidence indicates that the species is secure and not undergoing a decline in numbers.

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

Criterion 2 - Geographic distribution

On Christmas Island, Carmona is widespread on all terraces and occasionally occurs in plateau rainforest. The extent of occurrence is not known but its maximum extent of occurrence would be that of the entire island which is approximately 135 km2.

On Cape York Peninsula, Carmona has a naturally disjunct distribution and is recorded from eight localities which include northern, central and southern areas of the Cape York bioregion, indicating a linear range of approximately 630 km and an estimated extent of occurrence of about 38 400 km2 (Butz 2004) (this calculation of extent of occurrence appears to be the area contained within all known locations of the species on Cape York and does not exclude areas of obviously unsuitable habitat).

There are threatened processes operating on both Christmas Island and Cape York Peninsula, but Carmona does not appear to be affected to any degree by these threats.

Carmona is now considered to be widespread on Christmas Island and has been found at eight locations on Cape York Peninsula. Evidence indicates that the species is secure and that its geographic distribution is not limited or precarious for the survival of the species. Therefore, the species is not eligible for listing under this criterion.

Criterion 3 - Population size and decline in numbers or distribution

There is little information on the number of mature individuals of Carmona. On Christmas Island, Carmona is described as being common and widespread on all the terraces, and found in reasonably high densities with numerous populations. It is estimated to occur in the thousands (Butz 2004).

On Cape York Peninsula, there is little information available on the population numbers for Carmona other than being described as rare to common at Mount White near Coen, frequent at Birthday Mountain in Mungkan Kandju National Park and occasional at Ambition Scrub in Lakefield National Park (Butz 2004).

There is no data available to assess Carmona's numbers across its range. There are no known threats that are adversely affecting Carmona's long-term survival, and its geographic distribution is not precarious for its survival. Therefore, the species is not eligible for listing under this criterion.

Criterion 4 - Population size

There is little information on the number of mature individuals other than the anecdotal comments outlined in criterion 3. There is no quantitative data available against this criterion. Therefore, the species is not eligible for listing under this criterion.

Criterion 5 - Probability of extinction in the wild

There is no quantitative data available against this criterion.

5. Conclusion

On Christmas Island, Carmona is widespread on all terraces, and though its population numbers are not known, it is estimated to occur in the thousands. On Cape York Peninsula, Carmona is recorded from eight localities which include northern, central and southern areas of the Cape York bioregion, indicating a linear range of approximately 630 km and an estimated extent of occurrence of about 38 400 km2 . Though there are general threatening processes operating on both Christmas Island and Cape York Peninsula, Carmona does not appear to be affected by any of these threats and is considered to be secure.

Carmona is not eligible for listing under any criteria.

6. Recommendation

TSSC recommends that the list referred to in section 178 of the EPBC Act be amended by deleting from the list in the vulnerable category:

Publications used to assess the nomination

Butz, M. 2004. Draft National Recovery Plan for Carmona retusa. Unpublished report to the Department of the Environment and Heritage, Commonwealth of Australia, Canberra.