Wing-fruited Lasiopetalum (Lasiopetalum pterocarpum ms) Interim Recovery Plan 2003-2008

Interim recovery plan no. 134
Gillian Stack and Val English
Department of Conservation and Land Management, WA, 2003

1. Background

History

L. pterocarpum ms was poorly surveyed until 1997, when a floristic survey of the Darling Scarp was conducted by A. Markey ¹ (Markey 1997). No additional populations were located during this survey, or in other subsequent surveys undertaken by Departmental staff or volunteers, and the species was ranked Critically Endangered in November 1998.

Wildfire burnt Populations 1a and 1b to ash in December 1999, leaving just 10 adult plants at Population 1c. Seedlings have germinated in the areas of Populations 1a and 1b since the fire, but the identification of these as L. pterocarpum ms needs to be confirmed when they are sufficiently mature. An additional 7 plants were located at Population 1c in 2001, giving a total of 17 mature plants in the wild.

48 plants of Lasiopetalum pterocarpum ms were translocated into a new site in 2001. This site was chosen for its similarity in vegetation, soils and topography to the wild population, the low level of public access and weeds, and sufficient distance from the wild population to make the burning of both populations in the same fire unlikely. These plants appeared healthy and vigorous when monitored in March 2003.

An Interim Recovery Plan was written for Lasiopetalum pterocarpum ms in 1999 (Stack and English 1999). This plan is based on that document, includes additional information compiled since 1999, and replaces that plan.

Description

The winged membranous fruit is the main distinguishing feature of Lasiopetalum pterocarpum ms. The fruit has six to twelve elongated wings that usually consists of five large and several smaller wings. The fruit splits open when mature. The leaves are more obviously lobed than any other species of the genus Lasiopetalum. The bracteoles are linear and there are no petals or stipules. The apex of the style contains stalked star-shaped hairs (Brown et al. 1998).

Distribution and habitat

L. pterocarpum ms is endemic to the Serpentine area. It is known from a single wild population of just 17 plants that occur on either side of a stream (Population 1c). Populations 1a and 1b previously contained another 17 plants, but these were killed by wildfire in December 1999. These subpopulations appear to be regenerating well from seed, although identity still needs to be confirmed when plants mature. Population 1b is slightly higher in the landscape than Population 1a and is less likely to be subject to flooding. The population is located within National Park in a riparian community with Eucalyptus rudis, Eucalyptus calophylla, Agonis linearifolia and Melaleuca rhaphiophylla. Markey (1997) noted that this site was the only intact example of this type of riverine woodland within the northern Darling Scarp. The flow of water alongside the wetland habitat of Population 1 is artificially maintained by water piped to the weir adjacent to the population's wetland habitat. A second population of 48 plants has been translocated into an area of similar habitat with fewer threats.

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 (EPBC Act).

The critical habitat for L. pterocarpum ms comprises:

  • the area of occupancy of known populations;
  • areas of similar habitat within 200 metres of known populations, i.e. riparian community in Eucalyptus rudis / Eucalyptus calophylla woodland (these provide potential habitat for natural range extension);
  • remnant vegetation that links populations (this is necessary to allow pollinators to move between populations and in this case is National Park);
  • the water supply to the habitat of Population1 (Population 1 is likely to be dependent on the artificially maintained flows that sustain surface and ground water hydrology in the habitat); and
  • 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 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.

Benefits to other species/ecological communities

Recovery actions, such as weed control, implemented to improve the security of Lasiopetalum pterocarpum are likely to improve the quality of the habitat in which this population is 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 Australia's responsibilities under that Convention. However, as Lasiopetalum pterocarpum 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 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

Wild and translocated populations of Lasiopetalum pterocarpum ms are located on public lands. There are unlikely to be any major social or economic impacts associated with the implementation of actions held in this plan.

Evaluation of the Plan's 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

In general, Lasiopetalums are non-clonal single stemmed plants, and are obligate seeders (personal communication C. Wilkins ²). None of the adult plants of L. pterocarpum ms resprouted following the 1999 fire, and juvenile plants germinated from seed. It therefore appears that this Lasiopetalum is also an obligate reseeder.

Glasshouse trials indicate that L. pterocarpum ms is not susceptible to dieback caused by the plant pathogen Phytophthora cinnamomi (personal communication C. Crane ³). This appears to be supported by field observations prior to the fire, as many plants occurred in high recreational use areas but did not appear to suffer the impacts of the disease.

The pollinators of Lasiopetalums are generally native bees (personal communication C. Wilkins). L. pterocarpum ms has an aril on the seed, which suggests the seed is distributed by ants. The seed would be 'buried' underground when the ants carry them into their nests.

Threats

L. pterocarpum ms was declared as Rare Flora under the Western Australian Wildlife Conservation Act 1950 and ranked Critically Endangered in 1998. It currently meets World Conservation Union (IUCN, 2000) Red List Category 'CR' under criteria Ba1b(iii)+2ab(iii); C2a(i,ii) and D (IUCN 2000) as it is only known from a single wild population comprised of 17 mature individuals that occur over a very small range, with continued decline in the quality of the habitat. The species is also listed as Endangered under EPBC Act. The main threats are weed competition, trampling by recreational users in the National Park, inappropriate stream flows or water quality in the stream that flows adjacent to the wild population, and inappropriate fire regimes.

  • Weed competition is a major threat to the only wild population of the species. There is existing competition from blackberry (*Rubis aff. selmeri), watsonia (*Watsonia meriana) and gladioli (*Gladiolus undulatus), and cotton bush (*Gomphocarpus sp.) appears to be an emerging threat. Weeds suppress early plant growth by competing for soil moisture, nutrients and light.
  • Trampling by recreational users of the National Park is a threat to this species, as the only wild population occurs very near major walking tracks. Numerous visitors come to the Park each year and recreational use of some areas adjacent to trails leads to trampling and degradation of the habitat of L. pterocarpum ms. This may also lead to accidental destruction of L. pterocarpum ms plants.
  • Changes to streamflow or water quality are a threat to L. pterocarpum ms. The only wild population occurs in close proximity to a creekline. A gauging station is immediately upstream, and two additional dams are located further upstream of this population. The water flow at the latter two dams is controlled by the Water Corporation. Changes to stream flow or water quality as a result of any developments along the stream channel upstream have the potential to impact the population. Redevelopment of the recreational site adjacent to the population is recommended in the draft Management Plan for the National Park (Department of Conservation and Land Management 2000). This includes removal of the weir immediately upstream and expansion of the nearby carpark.
  • Inappropriate fire regimes may affect the viability of populations, as seeds of L. pterocarpum ms germinate following fire. The soil seed bank would rapidly be depleted if fires recurred before regenerating or juvenile plants reached maturity and replenished the soil seed bank. In addition, fires generally stimulate weed invasion and vigour, and weeds already infest the habitat of the wild population. However, it is likely that occasional fires are needed for reproduction of this species.
Summary of population information and threats
Pop. No. & Location Land Status Year/No. plants Condition Threats
1a. Serpentine National Park 1997 6
1999 7
2000 0 (?384)
2001 0 (?505)
Burnt 12.1999
Healthy regrowth
Weed competition, trampling, inappropriate water flow or quality, inappropriate fire regime
1b. Serpentine National Park 1997 2
1999 10
2000 0
2001 0
Burnt 12.1999 Weed competition, trampling, inappropriate fire regime
1c. Serpentine National Park 1999 10
2000 10
2001 17
Moderate Weed competition, trampling, inappropriate fire regime
2T. Serpentine National Park 2001 48 Good Inappropriate fire regime

Numbers in brackets = number of juveniles. '?' indicates seedlings require confirmation of identification when of sufficiently age.
In 2001, indentations on leaves indicate most or all of these seedlings are likely to be L. pterocarpum ms, and not other Sterculiaceae species.

Guide for decision-makers

Section 1 provides details of current and possible future threats. Any on-ground works (clearing, firebreaks, alteration of creek water levels etc) in the immediate vicinity of L. pterocarpum 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, or on the local hydrology.