Varnish bush (Eremophila viscida) Interim Recovery Plan 2003-2008

Interim recovery plan no. 137
Robyn Phillimore, Rebecca Evans, Andrew Brown & Val English
Department of Conservation and Land Management, WA, 2003

1. Background

History

The first known collection of Eremophila viscida was made from the Kununoppin area by F. E. Victor in 1916. Subsequently, collections have been made over a very large geographical range between Latham, Koorda, Carnamah, Ballidu (Merredin District) and Pindar (Geraldton District). Unfortunately, many of these collections have vague location details making surveys difficult.

In 1985, a report titled 'The vegetation, flora and avifauna of Chiddarcooping Nature Reserve" by A.S. Weston identified a new population of four plants in Chiddarcooping Nature Reserve. In 1993, as a result of research being undertaken by the Department's Science Division on six rare species of Eremophila, G. Richmond discovered a new population of E. viscida consisting of around 1000 plants on private property (Richmond and Coates 1995). The correct identification of plants in this population were subsequently confused with another Declared Rare Eremophila species E. virens which has similarly large waxy, green leaves and occurs at the same location. As a consequence, the area was not revisited until 2000.

Numerous surveys undertaken by staff from the Department's Nature Conservation Division, and Geraldton and Merredin Districts have resulted in the discovery of new populations near Pithara and south east of Mullewa. Currently, Eremophila viscida is known from 16 populations consisting of around 816 mature plants.

Description

Eremophila viscida is a large, erect shrub 2 to 6 m tall with sticky, shiny, brown, hairless branches and hairless to finely glandular-hairy leaves 5 to 10 cm long by 1 cm wide. The flowers are tubular, about 2 cm long, and are solitary or sometimes in twos. Each flower is on a 1 cm long stalk, which is enlarged beneath the flower. The calyx lobes are 7 mm long, greyish-blue or reddish in colour and are strongly veined. The corolla is white to pale yellow with purple spots. The stamens project beyond the floral tube. The ovary is hairy. Egg-shaped fruits are 5 to 7 mm long, 4 mm wide and are hairy on the upper part (Brown et al. 1998).

Eremophila viscida is distinguished from Eremophila lucida ms (Shining Poverty Bush) by its linear to lanceolate leaves, prominently spotted flowers and large greyish-blue or reddish calyx lobes (Brown et al. 1998).

Distribution and habitat

Eremophila viscida has a historical range of some 290 km between Latham, Koorda, Carnamah, Ballidu, Pindar and Merredin. It appears to prefer areas that are associated with granite and salt lake systems and plants are particularly frequent in runoff areas, including drainage lines or ephemeral creeks connected to granite outcrops. Preferred habitat is brown, sandy-loam or red brown clay-loam soils, in open woodland in association with Eucalyptus loxophleba and scrub vegetation (Mollemans et al. 1993).

Associated species include Melaleuca lateriflora, Acacia acuminata, Scaevola spinescens, Eucalyptus longicornis, Allocasuarina sp., Acacia coolgardiensis and Eremophila serrulata. Eremophila viscida also occasionally occurs with other threatened flora species including Eremophila virens and Caladenia drakeoides.

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 viscida 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.

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 is habitat critical. In addition all populations, including any translocated populations, are considered important to the survival of the species. Recovery actions include survey for further populations that would lead to the identification of additional habitat critical.

Benefits to other species/ecological communities

There are no known threatened ecological communities that occur in the habitat of Eremophila viscida However, several populations other threatened plant taxa (Eremophila virens and Caladenia drakeoides) will benefit from recovery actions put in place for the species. Recovery actions will also improve the condition of associated bushland in general.

Social and economic impacts

The implementation of this recovery plan has the potential to have some minimal social and economic impact, as several populations are located on private property. However, most landholders are amenable to managing the habitat of the species for conservation. Recovery actions refer to continued liaison between stakeholders with regard this. Future actions that could minimise potential impact may include fencing, land acquisition, covenants and management agreements.

Evaluation of the Plan's Performance

The Department of Conservation and Land Management, in conjunction with the Merredin and Geraldton District Threatened Flora Recovery Teams will evaluate the performance of this recovery plan. In addition to annual reporting on progress against the criteria for success and failure, the plan is to be reviewed within five years of its implementation. Any changes to management / recovery actions made in response to monitoring results will be documented accordingly.

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).

The critical habitat for Eremophila viscida comprises:

  • the area of occupancy of known populations;
  • areas of similar habitat within 200 metres of known populations (brown, sandy loam or red brown clay loam soils, in open woodland in association with Eucalyptus loxophleba and scrub vegetation) that provide potential habitat for natural recruitement);
  • remnant vegetation that surrounds and links populations (this is necessary to allow pollinators to move between populations);
  • 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); and
  • the local catchment for the surface and ground waters that provide the ephemeral creekline habitat of the species (the species occurs in areas that are seasonally inundated and depend on the local hydrology).

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

Given that this species is Critically Endangered it is considered that all known habitat is habitat critical. In addition all populations, including translocated populations, are considered important to the survival of the species.

Biology and ecology

Endemic to Australia where it is represented in all mainland states, Eremophila comprises some two hundred named and many unnamed species. While most occur in semi-arid and arid inland regions, they are extremely widespread over a wide geographic range, with some species found in the Western Australian Wheatbelt and others along the coast near Perth. Species in this genus are commonly known as emu bushes or poverty bushes.

A study on the storage ability of seed from 12 species of Eremophila in optimal conditions of low moisture content and low temperatures found E. viscida often exhibited better germination after one year in storage (50 to 100% germination) compared to fresh seed (87% germination). Therefore Eremophila seed has the potential for storage without loss of viability (Cochrane et al. 2002).

A visual assessment of the relative density of the starch grains within the root systems of Eremophila viscida show that it possesses characteristics of a resprouter. This has been confirmed by field observations, where suckering from disturbed root systems was evident. Due to the resinous nature of the leaves and stems, it is likely that E. viscida is highly flammable (Richmond and Coates 1995).

Eremophila viscida is a fast growing, widely distributed species. Although not common in cultivation, the species has great potential for use in semi-arid areas as a low windbreak and screening plant (Elliot and Jones 1984).

Threats

Eremophila viscida was declared as Rare Flora in October 1996 and ranked as Critically Endangered (CR) in February 1997. At that time it met World Conservation Union (IUCN 2000) Red List Category 'CR' under criteria A1c+A2c; C1; D but, following the discovery of new populations, it now (2003) meets EN under IUCN criteria A4c; C1 as it occurs over a wide geographical area between Merredin and Mullewa with 16 populations and 816 mature plants currently known. If current circumstances do not change a gradual reduction in plant numbers is likely due to senescence, resulting in a slow decline in area of occupancy and extent of occurrence. However, the species is a disturbance opportunist and recruitment is likely to occur during that time.

The main threats are poor recruitment, weeds, rising salinity and waterlogging, silting, erosion, inappropriate fire regimes, road, track and firebreak maintenance, grazing and trampling by stock, chemical drift and powerline maintenance.

  • Poor recruitement, due to lack of appropriate disturbance, threatens most populations as, with the exception of Population 16 which are all young plants, very few juvenile plants of Eremophila viscida have been observed. Most of the other threats listed below are also likely to affect recruitment adversely.
  • Weed invasion is a threat to most populations which occur in degraded habitat. Weeds suppress early plant growth by competing for soil moisture, nutrients and light. They also exacerbate grazing pressure and increase the fire hazard due to the easy ignition of high fuel loads, which are produced annually by many weed species.
  • Rising salinity and waterlogging resulting from agricultural clearing are impacting on Subpopulations 12b, 12c, 15a and 15b, and Populations 13 and 14. These threats are leading to degradation of the species' habitat and, if not addressed, will become worse in the medium to long term.
  • Silting of an ephemeral creekline is evident at Subpopulation 14c and is likely to be a threat to other populations that occur along watercourses. Silting may result in changes to water flow and water levels thereby altering the local hydrology on which Eremophila viscida is dependent.
  • Soil erosion is damaging the habitat of Subpopulations 12b and 12c. Land clearing has resulted in large volumes of water channeling down a creekline and eroding soil along its banks. Sheep moving through the area further exacerbate the problem by loosening soil with their hooves.
  • Inappropriate fire regimes may affect the long term viability of populations. It is thought that occasional fire or other disturbance is necessary for recruitment, however, frequent fire that occurs before regenerating or juvenile plants have reached maturity and have replenished the soil seed bank is likely to result in the loss of populations. Regeneration has been observed at Population 16 following a fire in 1998, and at Subpopulation 14c which was burnt a number of years ago (personal communication K. Brunt ¹ ).
  • Road, track and firebreak maintenance threaten most populations. Threats include grading, chemical spraying, construction of drainage channels and the mowing of roadside vegetation. Some of these actions also encourage weed invasion.
  • Grazing and stock disturbance (sheep and cattle) is a threat to Subpopulations 12b, 12c and 14b and 14c and a lesser threat to other private property populations. Plants at Population 14 have been subject to intense grazing pressure in the past and on many plants have left foliage only on upper branchlets. Increased nutrient levels from sheep and cattle droppings has resulted in the proliferation of weeds and trampling of vegetation is also impacting on the habitat of the species. Grazing may also have an impact on the establishment of Eremophila viscida seedlings thus limiting the natural recruitment of the species.
  • Grazing and trampling by feral animals such as rabbits (Oryctolagus cuniculus) have impacted on plants at Population 6 with stems bitten off and leaves chewed on one young plant. Rabbits are present at most populations and are damaging habitat during warren construction. Although it appears that larger Eremophila viscida plants are not grazed by goats they are impacting on the plant and its habitat at Population 16 by digging, trampling and breaking foliage when moving through the area. Increased nutrient levels in the soil from both rabbit and goat droppings is also likely and may result in increased weed invasion. Grazing would have an impact on the establishment of young plants of Eremophila viscida thereby limiting natural recruitment.
  • Chemical drift from herbicide and fertiliser applications during work on adjacent farmland may affect the species' long term survival.
  • Powerline maintenance is a potential threat to Subpopulation 11b. Disturbance during maintenance may encourage weed invasion and also directly damage plants. The relevant authority has been made aware of the population.
Summary of population information and threats
Pop. No. & Location Land Status Year/No. plants Condition Threats
1. NNE of Warralakin Nature Reserve 1985 4   Poor regeneration, weeds, inappropriate fire regimes
2A. NE of Warrachuppin Private Property 1990 1 Disturbed Poor regeneration, weeds, inappropriate fire regimes, stock disturbance.
2B. NE of Warrachuppin Shire Road Reserve 1986 1
2001 3
Poor Poor regeneration, weeds, road maintenance, inappropriate fire regimes.
3.SW of Mukinbudin Shire Road Reserve 1984 1
2000 2
Disturbed but plants healthy Poor regeneration, road maintenance, weeds, inappropriate fire regimes.
4. S of Warrachuppin Shire Road Reserve 1980 5
2000 0
Poor Poor regeneration, road maintenance, weeds, inappropriate fire regimes.
5. NW of Warralakin Shire Road Reserve 1991 1
2000 0
Poor Poor regeneration, road maintenance, weeds, inappropriate fire regimes.
6. NE of Mukinbudin Shire Road Reserve 1992 5
2000 4 (1)
Moderate Poor regeneration, road maintenance, weeds, grazing, inappropriate fire regimes.
7A. N of Warralakin Shire Road Reserve 1991 27 (1) [2 dead]
2000 6 [4 dead]
Moderate/ Poor Poor regeneration, road maintenance, weeds, inappropriate fire regimes.
7B. N of Warralakin Private Property 1991 2
2000 1
Moderate Poor regeneration, chemical drift, weeds, firebreak maintenance, inappropriate fire regimes.
8. SSE of Mount Grey Private Property 1992 1
2000 0
Disturbed Poor regeneration, stock disturbance, weeds, inappropriate fire regimes.
9. SE of Mount Grey Private Property 1992 1
2000 0
Disturbed Poor regeneration, stock disturbance, weeds, inappropriate fire regimes.
10. S of Warrachuppin Shire Road Reserve 1980 4
2000 5
Disturbed Poor regeneration, road maintenance, weeds, chemical drift, inappropriate fire regimes.
11A. Warrachuppin Shire Road Reserve 1980 1
2000 2
Disturbed Poor regeneration, road maintenance, weeds, inappropriate fire regimes.
11B. Warrachuppin Private property 1993 2
2000 2
Disturbed Poor regeneration, road maintenance, weeds, powerline maintenance, chemical drift, inappropriate fire regimes.
12A. NW of Warralakin Shire Road Reserve 2000 2 [1 dead] Moderate Poor regeneration, road maintenance, weeds, inappropriate fire regimes.
12B. NW of Warralakin Private Property 1993 450
2000 400 [30 dead]
Moderate/ Poor Poor regeneration, stock disturbance, salinity, erosion, chemical drift, weeds, firebreak maintenance, inappropriate fire regimes.
12C. NW of Warralakin Private Property 1993 1000
2001 229 (4) [15 dead]
Moderate/ Poor Poor regeneration, stock disturbance, salinity, erosion, chemical drift, weeds, firebreak maintenance, inappropriate fire regimes.
13. NW Pindar Pastoral Lease 1997 2
2001 (1)
Poor Poor regeneration, salinity, weeds, inappropriate fire regimes.
14A. SE of Pithara Private Property 2000 1
2001 1
Poor Poor regeneration, salinity, weeds, inappropriate fire regimes.
14B. SE of Pithara Private Property 2001 2 Poor Poor regeneration, grazing, weeds, salinity, inappropriate fire regimes, chemical drift, firebreak maintenance, stock disturbance.
14C. SE of Pithara Private Property 2001 50+ Poor Poor regeneration, grazing, weeds, salinity, inappropriate fire regimes, chemical drift, stock disturbance, silting.
15A. SE of Mullewa Shire Road Reserve 2001 4 [1 dead]
2003 2 [3 dead]
Moderate Poor regeneration, road maintenance, salinity, inappropriate fire regimes.
15B. SE of Mullewa Private Property 2001 19 [20 dead] Poor Poor regeneration, salinity, inappropriate fire regimes, grazing.
16A. SE of Mullewa Conservation Park (Leased by the Dept) 2001 *80 [1 dead] Healthy Firebreak maintenance, inappropriate fire regimes, grazing.
16B. SE of Mullewa Unallocated Crown Land 2001 *see above [1 dead] Healthy Firebreak maintenance, inappropriate fire regimes, grazing.

Numbers in brackets = number of seedlings. * = total for subpopulations combined.

Guide for decision-makers

Section 1 provides details of current and possible future threats. Developments in the immediate vicinity of the population or within the defined critical habitat of Eremophila viscida require assessment. No developments should be approved unless the proponents can demonstrate that they will not have a deleterious impact on the species, or its habitat or potential habitat, or the local surface and ground water hydrology.