Pinnate-leaved Eremophila (Eremophila pinnatifida ms) Interim Recovery Plan 2002-2007

Interim recovery plan no. 124
>Gillian Stack and Andrew Brown
Department of Conservation and Land Management, WA, 2003

1. Background

History

R. Chinnock discovered this species near Dalwallinu in 1990 and counted a total of 35 plants. Despite further searches over several years no more plants were found until 1996, when G. Richmond conducted a survey in the Dalwallinu townsite on behalf of Main Roads Western Australia (MRWA), with reference to a proposed Dalwallinu by-pass. He found an additional population of two plants within the Dalwallinu townsite, in an area where roadworks were proposed. In January 1997, Merredin District staff and G. Richmond surveyed existing populations and all similar habitat on road and other reserves within a 15 km radius of Dalwallinu. They did not find any more plants, but established that the original population had declined from 35 to six plants (no plants remained in 2000 and this population is now considered extinct). A third population was found in October 1998 by A. Brown of the Western Australian Threatened Species and Communities Unit (WATSCU). This road reserve population contains 14 plants in very degraded habitat that is being eroded by water running off the adjacent road.

Fortunately, further populations have since been found which contain a much larger numbers of plants, but both occur at sites vulnerable to a range of threats. In 2001, Subpopulation 1b was discovered and comprises some 200 mature plants and 170 juveniles (all 355 are mature in 2002 and 15 have died). This population is in an area subject to a housing development proposal and is extremely degraded and weedy. Population 4 (discovered by A. Brown) contained 78 plants in 2001 and occurs on a narrow, weedy road verge.

Description

Eremophila pinnatifida ms is an erect rounded shrub to approximately one metre tall. Leaves are in whorls of three and are deeply lobed - the source of the specific name. The flower tube is pale to deep purple and pubescent outside, and white with pale purple spots inside. The species is allied to E. ternifolia and E. koobabbiensis ms. Like these species it has leaves in whorls of three and a similarly structured fruit, but differs from E. ternifolia and other related species such as E. sargentii and E. verticillata by its diagnostic lobed leaves and the prominent pubescence on its branches and leaves. It differs from E. koobabbiensis in its larger flowers and more prominently lobes leaves.

Distribution and habitat

E. pinnatifida ms appears to be endemic to the Dalwallinu area where it is known from four populations with a combined total of 464 mature plants. The species occurs in areas of tall open Eucalyptus salmonophloia and E. loxophleba woodland over sparse mixed shrubland of Santalum acuminatum, Eremophila drummondii and Acacia species over mixed chenopods and perennial grass on brown clay loams.

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)).

The critical habitat for Eremophila pinnatifida ms comprises:

  • the area of occupancy of known populations;
  • areas of similar habitat within 200 metres of known populations, i.e. tall open woodland over sparse mixed shrubland on brown clay loams (these provide potential habitat for natural recruitment);
  • corridors of remnant vegetation that link populations (these are necessary to allow pollinators to move between populations and are usually road and rail reserves);
  • 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).

Habitat critical to the survival of the species, and important populations

Given that this species is listed as Critically Endangered it is considered that all known habitat for wild and any translocated populations is habitat critical.

Benefits to other species/ecological communities

There are no threatened ecological communities or other threatened species in the immediate vicinity of Eremophila pinnatifida ms. However, recovery actions implemented to improve the quality or security of the habitat of the species, such as weed control and rehabilitation, will benefit the remnant bushland habitat in which it occurs.

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 Australia's responsibilities under that Convention. However, as Eremophila pinnatifida ms is not listed under any international agreement, the implementation of other international environmental responsibilities is not affected by this plan.

Role and interests of indigenous people

There are no known indigenous communities interested or involved in the management of areas affected by this plan. Therefore no role has been identified for indigenous communities in the recovery of this species.

Social and economic impacts

The implementation of this recovery plan is unlikely to cause significant adverse social and economic impacts. One population of Eremophila pinnatifida ms occurs in an area of Shire land that had been set aside for possible future housing development However, negotiations between relevant parties have ensured that the area directly supporting this species will be set aside as Public Open Space, and subsequently vested in the Conservation Commission for the purpose of Conservation.

Evaluation of the Plans Performance

The Department of Conservation and Land Management, in conjunction with the Recovery Team will evaluate the performance of this IRP. 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.

Biology and ecology

Very little is known about the biology and ecology of the species .G. Richmond ¹ (personal communication) has suggested that it may have a short life cycle of approximately 10 years. It appears to be a disturbance opportunist, with germination stimulated by fire or earth movement. A resident of Dalwallinu does not recall a fire occurring in the reserve containing Population 1 within the last 10 years. It seems likely that the decline of Population 1 since its discovery is a result of the existing plants reaching the end of their life cycle and not being replaced due to a lack of appropriate disturbance.

Seed was collected from Population 1 by A. Cochrane of the Department's Threatened Flora Seed Centre (TFSC) in July 1997, and this had an extremely low seed to fruit ratio. In 100 fruits four seeds were found, none of which germinated under laboratory conditions before going mouldy. It has been suggested this was possibly because they were not taken completely out of an extremely hard coating (personal communication A. Cochrane ² ). This low rate of seed production may be at least partly due to the low genetic diversity of the population and the age of the plants. Fruit produced earlier when there were more plants in the population may have had a higher seed to fruit ratio.

¹ Guy Richmond, formerly at Curtin University
² Anne Cochrane, Manager, the Department's Threatened Flora Seed Centre

Threats

Eremophila pinnatifida ms was Declared as Rare Flora on 28 November 1997, and ranked as Critically Endangered (CR) in November 1998. It currently meets World Conservation Union (IUCN, 2000) Red List Category 'CR' under criteria B1ab(iii)+2ab(iii) due to the severe fragmentation of populations and continuing decline in the quality of its habitat. The main threats are housing development, road maintenance, erosion, weeds, degraded habitat and inappropriate fire regimes.

  • Housing development is proposed to occur within the reserve that Population 1b inhabits. Negotiations between relevant parties have ensured that the area directly supporting this species will be set aside as Public Open Space, and subsequently vested in the Conservation Commission for the purpose of Conservation. However, clearing of nearby vegetation is likely to further reduce populations of pollinators, and an influx of people is likely to increase the recreational usage of the conservation reserve. In addition, the habitat may be affected by the addition of fertilisers to gardens and the water table affected by water usage.
  • Road maintenance such as grading, construction of drainage channels, mechanical slashing of vegetation and weed spraying pose a threat to Populations 2, 3 and 4. Several of these actions also encourage weed invasion. Populations 2, 3 and 4 occur on road reserves and are subject to modified hydrology.
  • Erosion is a threat to Population 3 as the drainage channel along which it occurs is becoming increasingly eroded by water running off the road surface. Two plants have died, and a third has some roots exposed.
  • Weeds are a major threat to the long-term viability of Populations 1, 2 and 4 where wild oats (Avena fatua) constitute the dominant understorey. Although weeds do not appear to pose a threat to existing plants they are vigorous and inhibit natural recruitment. Population 2 has been invaded by a range of grass and broadleaf weeds, including soursob (Oxalis pes-caprae) and several species of medic (Medicago spp).
  • Degraded habitat represents a threat to all four populations. The lack of associated native vegetation makes it more likely that pollinators will be infrequent or absent. In addition, the lack of available habitat for recruitment is of concern. Three of the four populations occur on narrow road reserves with cleared land beyond.
  • Inappropriate fire regimes may affect the viability of populations. Seeds of E. pinnatifida ms probably germinate following fire. If this is the case, the soil seed bank would rapidly be depleted if fires recurred before regenerating or juvenile plants reached maturity and replenished the soil seed bank. However, it is likely that occasional fires are needed for reproduction of this species. A resident of Dalwallinu does not recall a fire occurring in the reserve containing Population 1a within the last 10 years.
  • Poor recruitment threatens most populations with few seedling plants being observed. This is most acute at Population 1a, where the plants appeared to have grown in response to a single disturbance event prior to 1990. The plants are now dead and disturbance is necessary to stimulate germination of any soil-stored seed.
Summary of population information and threats
Pop. No. and Location Land Status Year/No. plants Condition Threats
1a. Dalwallinu Shire Reserve 1990 35
1997 6
1998 2
2000 0
Extinct Lack of disturbance, weeds, degraded habitat, inappropriate fire regimes
1b. Dalwallinu Shire Reserve 2000 3 (367)
2001 200 (170)
2002 355 [15 dead]
Healthy Housing development, installation of pipeline, weeds, degraded habitat, inappropriate fire regimes
2. Dalwallinu Shire Road Verge 1997 2
1998 3
2001 2
Poor Road maintenance, weeds, degraded habitat, inappropriate fire regimes
3. Dalwallinu MRWA Road Verge 1998 16
1999 16
2001 14
Moderate Road and drain maintenance, erosion, weeds, degraded habitat, inappropriate fire regimes, lack of habitat
4. Dalwallinu Shire Road Verge 2001 78 Healthy Road maintenance, weeds, degraded habitat, inappropriate fire regimes

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. pinnatifida ms 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, its habitat or potential habitat.