National recovery plan for Zieria lasiocaulis

NSW National Parks and Wildlife Service, 2002
ISBN 0 731 36892 4

8. Management issues

8.1 Threats and reasons for decline

There is no evidence to show that populations of Z. lasiocaulis have declined in recent times. As there are no historic records outside the area of occurrence, and all populations occur on very restricted geological types, it is also likely that the distribution of Z. lasiocaulis has not been significantly reduced in recent times. A limited geographic distribution is consistent with the characteristics of the genus Zieria (Armstrong 2002).

The threats to the populations of Z. lasiocaulis have changed since the recent inclusion of its habitat in Willi Willi National Park. Prior to dedication as National Park, much of the area was State Forest available for timber harvesting. Disturbance associated with timber harvesting no longer needs to be considered.

Threats that need to be considered include inappropriate fire regime, road or track construction and maintenance, and potential development of recreational facilities. These activities could have a direct impact on populations of Z. lasiocaulis unless adequate planning and site assessment is carried out.

The main threat to this species is likely to be an inappropriate disturbance regime. Although it appears to require some form of disturbance for germination and recruitment, the natural disturbance regime through events such as wildfire and storm damage (tree fall gaps and soil slips) must be adequate for the perpetuation of this species. As it is not known how current management practices affect the germination and persistence of Z. lasiocaulis, it is critical that research into the biology, and monitoring of the population demography, of Z. lasiocaulis be carried out. It is likely that too-frequent fires (

Z. lasiocaulis contains cyanogenic glycosides (naturally occurring organic compounds that contain cyanide) and is potentially toxic (Armstrong 2002), making it unlikely that plants would be browsed by either native or feral herbivores. At the time of preparation of this recovery plan invasive plant species and feral animals were not considered to be a threat to any of the known populations of Z. lasiocaulis.

8.2 Social and economic consequences

Associated costs of this recovery plan can be located in Table 2 .

Intrinsic ecological value

The ecological function of Z. lasiocaulis is not known. However, given optimum conditions, it forms dense stands and may be an important coloniser of disturbed sites in this area. All species have intrinsic ecological values, and have the right to exist independently.

Scientific and taxonomic value

The genus Zieria contains many species with restricted natural distributions, and the study of the biogeography, biology and genetics of such groups of species may help with understanding the processes of speciation and extinction.

Biodiversity value

The presence of Z. lasiocaulis in a number of vegetation communities within its restricted area of occurrence makes these communities unique. Rare and threatened plant species such as Z. lasiocaulis represent those species most likely to become extinct due to human-induced causes. Consequently, Z. lasiocaulis is a priority species to consider in conservation efforts aimed at arresting further loss of biodiversity from our natural ecosystems.

Commercial and pharmaceutical value

Z. lasiocaulis currently has no known commercial or pharmaceutical value. The family Rutaceae contains many species that are used commercially. For example, the cut flower industry (e.g. Boronias), food plants (citrus fruits), and timber (e.g. Australian Teak Flindersia australis) (Harden 2002).

Social benefits

The preparation of a recovery plan for Z. lasiocaulis will provide an information base for future management and research of this species. Given that the commercial and pharmaceutical value of Z. lasiocaulis is unexplored at this stage, future direct benefits cannot be quantified.

Increased community awareness of threatened species such as Z. lasiocaulis should increase support for the conservation of such species and, as a result, for the protection of biodiversity.

8.3 Biodiversity benefits

The occurrence of Z. lasiocaulis contributes to the high biodiversity of the flora of the north coast of NSW. The presence of Z. lasiocaulis in a number of vegetation communities within its known habitat makes these communities unique.

The conservation of Z. lasiocaulis in the wild could also benefit other plant and animal species and communities of conservation significance that occur in or near the habitat of Z. lasiocaulis. A plateau just west of Mount Banda Banda displays the best developed stand of cool temperate rainforest of the Nothofagus-Ceratopetalum sub-alliance in NSW (Floyd 1990). The habitat of Z. lasiocaulis is also habitat for several species of threatened fauna including Rufous Scrub-bird (Atrichornis rufescens), Tiger Quoll (Dasyurus maculatus) and Sphagnum Frog (Philoria sphagnicolus).

Significant plant species that will benefit from the conservation of Z. lasiocaulis and its habitat include Grevillea guthrieana (TSC Act Endangered). A small population occurs just north-west of Mount Banda Banda. A disjunct occurrence of the tussock grass Dryopoa dives (otherwise known from south of Robertson on the NSW southern highlands), and an undescribed species of Astrotricha that is considered rare (B. Makinson, pers comm) also occur in the locality. A newly described species of Solanum (Solanum curvicuspe) has been recorded in the general vicinity in similar habitats to Z. lasiocaulis (Bean 2001). Bean (2001) proposes a category of "vulnerable" for the conservation status of this species.

By increasing the public awareness of threatened plants such as Z. lasiocaulis, the conservation of other threatened species and biodiversity in general is encouraged.

9.1 Taxonomic research

A draft systematic and evolutionary study of the genus Zieria was prepared by J. A. Armstrong about ten years ago. This manuscript is yet to be published.

9.2 Targeted survey

Targeted surveys for Z. lasiocaulis were carried out during late 1997 as part of the Comprehensive Regional Assessment of North-east NSW forests (NSW NPWS 1999). Known localities from herbarium records were visited and other suitable habitat for Z. lasiocaulis in the general area of occurrence was searched. Details of population size, physical attributes and vegetation community were recorded at each site where Z. lasiocaulis was located.

9.3 Monitoring

Marked monitoring plots were established in 2001 to sample each of the main populations of Zieria lasiocaulis. Seven monitoring plots in total have been established and have recorded population numbers, age structure, reproductive status of plants and dominant species associated with each site. A proforma (Appendix 1) was developed to consistently record monitoring information.

10. Species' ability to recover

There is no evidence to indicate that Z. lasiocaulis has undergone a significant reduction in either population size or distribution, and it appears to have a number of germination and recruitment strategies. Provided a suitable disturbance regime is established and maintained, it is expected that the species will maintain populations in the wild.

As population sizes and structure of Z. lasiocaulis vary with time since disturbance it can be expected that populations will exhibit variations from 1000's of seedlings soon after a disturbance event to few remaining mature adults following a long period without disturbance. The population may also exist only as a soil seedbank(Section 4.2) until a disturbance event such as fire triggers germination of plants. The absence of a large number of plants is not necessarily a reflection of a decline in the species, but often the time since disturbance.

11. Recovery objectives and performance criteria

11.1 Objectives of the recovery plan

The overall objective of this recovery plan is to protect populations of Z. lasiocaulis from decline induced by non-natural impacts, and to ensure that wild populations of Z. lasiocaulis remain viable in the long-term.

Specific objectives of this recovery plan are to:

  • protect and maintain new and existing wild populations of Z. lasiocaulis and their habitat from threatening processes;
  • improve the knowledge of the distribution, ecology, biology, population demographics and genetics of Z. lasiocaulis to enable appropriate management;
  • protect any new populations and their habitat by suitable measures;
  • ensure that land managers are familiar with Z. lasiocaulis;
  • monitor known populations of Z. lasiocaulis;
  • assess the need for ex situ conservation;
  • increase community awareness of Z. lasiocaulis in particular, and threatened plant species in general; and
  • assess whether the declaration of critical habitat for Z. lasiocaulis under the TSC Act would deliver demonstrable conservation benefits.

11.2 Recovery performance criteria

Recovery criteria are that:

  • new and existing wild populations of Z. lasiocaulis are protected and maintained by suitable measures;
  • knowledge of the distribution, ecology, biology, population demographics and genetics relevant to appropriate management of Z. lasiocaulis is improved;
  • land managers are able to recognise Z. lasiocaulis;
  • populations are monitored;
  • the need for ex situ conservation is investigated and undertaken if appropriate;
  • educational material on Z. lasiocaulis is available to the community; and
  • assessment of the need for critical habitat for Z. lasiocaulis is undertaken.