Dandaragan Mallee Eucalyptus dolorosa Interim Recovery Plan 2004-2009

Western Australian Threatened Species and Communities Unit (WATSCU)
© The Western Australian, Department of Conservation and Land Management, 2004

1. Background

History

The first collection of Eucalyptus dolorosa was made in 1987 by M.I.H. Brooker. It has only ever been known from the slopes and summit of a single lateritic hill in the Dandaragan area. This area was burnt in 1978, and although the population flowered every year after its discovery in 1987, it didnt produce fruit until 1991. The area was fenced from stock in the late 1980s, protecting this species and a number of other threatened and Priority species that also occur in this area of remnant mallee heath. Plants occur in eight clumps, all of which are in good health. Brooker and Hopper (1993) noted that this species persists in a refugial site, and suggested that E. dolorosa is probably a relict species, barely surviving extinction as a consequence of a drying climate in the late Pleistocene period.

Description

Eucalyptus dolorosa is a low mallee to 2.5 m tall with stout stems and rough grey bark on the older stems. The juvenile leaves are broadly falcate, and light bluish-grey in colour. The adult leaves are slightly glossy, green in colour, lanceolate to falcate, measuring 10 x 2 cm. They have a moderately dense vein network and numerous oil glands. The inflorescences are axillary, but are clustered at the leafless ends of branchlets, appearing to be terminal. There are 7 flowers in each. The buds have pedicels up to 1 cm long and are rhomboid in shape, 9 x 6 mm with a slightly beaked operculum. The stamens are very numerous. The fruits have stalks to 7 mm long, and are cup-shaped to globose, measure 1 x 1.4 cm, and have four valves. The seeds are brown, pyramidal and winged (Patrick and Brown 2001)

This species is distantly related to Eucalyptus lateritica and E. todtiana, differing in its small falcate leaves, apparently terminal inflorescences, long pedicels, and glaucous juvenile leaves. The winged seed places this species in a group which includes E. buprestium, E. erectifolia and E. johnsoniana.

Distribution and habitat

Eucalyptus dolorosa is known from a single population west of Dandaragan. It is confined to lateritic breakaway slopes and a summit in mallee heath over low scrub, amongst massive ironstone blocks. Associated species include Eucalyptus arachnaea, E. gittinsii, E. pluricaulis, E. abdita, Hakea lissocarpha, H. obliqua, H. undulata, Calothamnus quadrifidus, Melaleuca radula, Acacia pulchella, Scholtzia sp. and Eremaea asterocarpa (Patrick and Brown 2001).

Biology and ecology

Eucalyptus species are typically highly adapted to surviving fires, which are a regular occurrence in many Australian habitats. Seedlings tend to be slow-growing, as much energy is channeled into the production of a lignotuber. After fire has removed or damaged above-ground parts of an established plant, a number of replacement stems are initiated from the lignotuber, producing the mallee form. Fire often also stimulates germination of Eucalyptus seed.

The only known population of E. dolorosa was burnt in 1978. It regenerated and was flowering in 1987, the year of its discovery. Flowers may also have been produced prior to this time. However, no fruit was produced until 1991, some twelve years after fire. It does not tend to produce a lot of flowers or fruit at once, producing small quantities somewhat sporadically. Some seed has been collected, but the viability of that seed has not yet been assessed.

Threats

Eucalyptus dolorosa was declared as Rare Flora under the Wildlife Conservation Act 1950 in July 1989. It currently meets Critically Endangered (CR) under World Conservation Union (IUCN) Red List criterion D (IUCN 2000), as there is only one population that contains very few plants. E. dolorosa is listed as Endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The main threats are inappropriate fire regimes, lack of recruitment and restricted distribution.

  • Inappropriate fire regimes may affect the viability of the population, as E. dolorosa is thought to resprout following fire. If this is the case, the lignotubers may be depleted if fires recur before they can build up resources again. Frequent fire is also likely to degrade the supporting ecological community, altering species composition as well as fostering weed invasion and erosion. This species is likely to need fire for recruitment of new individuals, but the long lifespan of Eucalyptus species suggests that there is no urgent need for fire in the short to mid-term (Dr Colin Yates, Senior Research Scientist (Ecology), CALMs Science Division, pers. comm.).
  • Lack of recruitment is apparent with no juvenile plants observed. Only small quantities of seed tend to be produced at any one time. The lack of recruitment may be due to poor seed viability, an absence of germination triggers or possibly poor seedling survival.
  • Highly restricted distribution means that all individuals of the species are likely to be affected by any single catastrophe that occurs, such as disease or a severe weather or fire event.
  • Weed invasion could become a threat to the population only under specific post-fire conditions. Although it remains almost entirely weed-free at present, it is possible that weed invasion may increase after fires and this will need to be monitored.

Summary of population information and threats

Pop. No. & Location Land Status Year/No. plants Condition Threats
1. WSW of Dandaragan Private property 1988 8 clumps
1991 ca. 20
1992 ca. 25
2000 ca 8 clumps
2003 ca 8 clumps
Healthy Too frequent fire, lack of recruitment

Guide for decision-makers

Section 1 provides details of current and possible future threats. Any on-ground works (clearing, firebreaks, roadworks etc) in the immediate vicinity of E. dolorosa will require assessment. On-ground works should not be approved unless the proponents can demonstrate that they will not have an impact on the species, or on its habitat or potential habitat.

Critical habitat

Critical habitat is habitat identified as being critical to the survival of a listed threatened species or listed threatened ecological community. Habitat is defined as the biophysical medium or media occupied (continuously, periodically or occasionally) by an organism or group of organisms or once occupied (continuously, periodically or occasionally) by an organism, or group of organisms, and into which organisms of that kind have the potential to be reintroduced (Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)).

Eucalyptus dolorosa is listed as Critically Endangered, and as such it is considered that all known habitat for wild and translocated populations is critical habitat. This includes:

  • the area of occupancy of known (wild and translocated) populations;
  • areas of similar habitat within 200 metres of populations, i.e. mallee heath over low scrub on lateritic breakaway slopes and summits with massive ironstone (these provide potential habitat for natural range extension);
  • additional occurrences of similar habitat that do not currently contain the species but may have done so in the past (these represent possible translocation sites).

Benefits to other species or ecological communities

The habitat supporting Eucalyptus dolorosa is highly species rich, and contains a number of threatened and Priority flora species. The following species occur on the same lateritic hill as E. dolorosa: Acacia forrestiana (DRF, ranked Vulnerable under the Wildlife Conservation Act and the EPBC Act); Grevillea synapheae subsp. A Flora of Australia, Lasiopetalum miseryense and Melaleuca clavifolia (Priority 1); Boronia scabra subsp. condensata, E. abdita and Stylidium aeonioides (Priority 2); Beaufortia eriocephala and Gastrolobium axillare (Priority 3); and Asterolasia drummondii (Priority 4). Recovery actions such as protecting E. dolorosa populations from frequent fire will also help to conserve the ecological community in which the populations are located.

International Obligations

This plan is fully consistent with the aims and recommendations of the Convention on Biological Diversity, ratified by Australia in June 1993, and will assist in implementing Australias responsibilities under that Convention. However, as E. dolorosa is not specifically listed under any international agreement, the implementation of other international environmental responsibilities is not affected by this plan.

Role and interests of indigenous people

Indigenous communities interested or involved in the regions affected by this plan have not yet been identified. The Aboriginal Sites Register maintained by the Department of Indigenous Affairs does not list any significant sites in the vicinity of these populations. However, not all significant sites are listed on the Register. Input and involvement will be sought from any indigenous groups that have an active interest in the areas that are habitat for Eucalyptus dolorosa, and this is discussed in the recovery actions.

Social and economic impacts

The only population of Eucalyptus dolorosa occurs on private land and negotiations will continue with regard to the future management of this population. The landholders are very supportive of managing this area of remnant vegetation for conservation.

Evaluation of the Plans Performance

CALM will evaluate the performance of this IRP in conjunction with the Moora District Threatened Flora and Communities Recovery Team. In addition to annual reporting on progress with listed actions and comparison against the criteria for success and failure, the plan is to be reviewed within five years of its implementation.