Zieria granulata (Illawarra Zieria) Recovery Plan

NSW Department of Environment and Conservation, 2005
ISBN: 1 7412 2143 9

8 Management Issues

8.1 Introduction

The following section identifies the management issues affecting Z. granulata including:

  • Our limited knowledge of the species biology and ecology;
  • The threats operating on the species;
  • Prioritising the recovery effort;
  • Community awareness of the species;
  • Consideration of a translocation and ex-situ conservation program; and
  • Consideration of the species ability to 'recover'.

8.2 Limits to current knowledge

The level of information that is known about Z. granulata (as detailed in sections 5 and 6) is limited and only broad assumptions can be made regarding its biology and ecology. An enhanced knowledge of key aspects of the species biology and ecology is clearly required if land managers and consent/determining authorities are to make informed judgements regarding its conservation requirements.

Future research should target aspects that are relevant to the practical management of the species and its habitat. High priority research projects for the species (as identified in Section 6) are described below.

Reproductive maturity

Investigation of the age of reproductive maturity of Z. granulata is required.

Seed ecology

Investigation of the nature of the Z. granulata soil seed bank is required. This should include investigation of the period that the soil seed bank remains viable and the identification of seed dormancy and germination mechanisms.

Fire and disturbance ecology

An assessment of the response of the species (including the soil seed bank) to different fire and disturbance regimes is required.

Genetic investigation

While not essential to its practical management, genetic investigations across the natural range of Z. granulata would greatly improve our understanding the population structure of the species, and this could inform land-use and recovery planning decisions.

8.3 Threatening processes

The threats operating at Z. granulata sites are described below and an assessment of the threat level at each site is included at Appendix 4.

8.3.1 Clearing for agriculture

The clearing of vegetation for agriculture (primarily for cattle grazing, dairying and horse agistment) is a potential threat to Z. granulata on a number of rural properties. Liaison with the owners of these properties is required to prevent the inadvertent clearing of habitat for the species.

Where clearing approvals are required, access to accurate site location records will assist consent and determining authorities in considering the conservation requirements of the species. Sufficient vegetated buffers should be retained around sites that contain Z. granulata to maintain the integrity of its habitat. The extent and design of the buffers required to achieve this will be site specific, depending on factors including aspect and slope (and their influence on a sites exposure to insolation and wind and the latters influence on drainage patterns) and the adjacent landuse.

8.3.2 Hard rock quarrying

The close association between Z. granulata and sites with a latite substrate has placed the species under threat from hard rock quarrying activities. Twenty sites in the Dunmore Hills area occur on land that has been identified by the NSW Department of Mineral Resources as containing a state significant latite resource (Zg9 to Zg21, Zg33 to Zg37, Zg93 and Zg97). This includes two sites that have been described as containing thousands of Z. granulata plants (Mills & Jakeman 1993).

Mining interests own 18 of these sites, and the other two sites are located on crown land that forms part of the Dunmore Quarry (Zg20 and Zg21). Of these, nine sites are zoned 4(a) Extractive Industry and four sites are zoned 1(a) Rural, a zoning which permits mineral extraction with development consent. The other seven sites are zoned 7(e) Environmental Protection (Scenic).

Shellharbour Council is to commence preparation of a Local Environmental Plan and Local Environment Study that reviews the mineral extraction boundaries in the Dunmore Hills area. The preparation of these documents will provide an opportunity to protect Z. granulata and its habitat from the direct and indirect impacts (altered hydrological conditions, dust etc) of quarrying through the rezoning process. Targeted survey as part of this process will be necessary to ensure that all locations of the species within the study area are identified and considered in the preparation of these documents.

Mining interests also own a site at Bombo (Zg56) in Kiama LGA. A part of this site has recently been the subject of a rezoning proposal to allow expansion of an adjacent quarry. If approved, the proposal will result in the removal of 12 Z. granulata plants (and an undetermined proportion of the soil seedbank) at that site.

8.3.3 Residential development

Population growth in the Illawarra is likely to place Z. granulata under increasing pressure from residential development. Such development, in addition to directly impacting upon the species through habitat loss and fragmentation, can indirectly affect sites in proximate or downslope locations by modifying environmental conditions, and contributing to habitat degradation.

These impacts can result from factors including:

  • Altered hydrological flows (and associated problems with sedimentation and erosion);
  • Altered soil pH and nutrient levels;
  • Weed infestations;
  • Increased pedestrian/vehicular access to sites;
  • Rubbish and green waste dumping;
  • Bushfire hazard reduction works;
  • Inappropriate landscaping activities; and
  • Arson.

Accurate and readily accessible site location records will assist consent and determining authorities in considering the conservation requirements of the species during the assessment of rezoning and development applications. Methods to mitigate direct and indirect impacts on the species should be incorporated into the design of developments that are to be constructed upslope of, or proximate to, Z. granulata sites.

Recent residential developments at Shellcove (Zg22) and Blackbutt (Zg1) have resulted in the loss of Z. granulata plants and habitat. The consent conditions for these developments required adjacent areas of habitat, which also contain the species, to be transferred to council as public reserves. On-going active management of these reserves is needed to mitigate the indirect impacts of the developments. Such management may include bush regeneration, fencing, track construction, and liaison with local residents to prevent rubbish dumping and other undesirable activities.

8.3.4 Grazing and associated activities

Mills & Jakeman (1993) list grazing and other farming activities as the most frequently recorded threat at the 33 Z. granulata sites surveyed during the preparation of that report. Grazing and trampling by livestock (ie horses and cattle) and slashing to maintain paddocks were recorded as threats at a number of additional sites that were surveyed during the preparation of this plan (M. Bremner, DEC, pers. comm.).

Landholders are generally unaware of the presence of Z. granulata on their property and the impact that their activities are having on the species. Liaison with these landholders is required to raise awareness of the species and facilitate the implementation of protection measures, particularly fencing to exclude livestock and machinery. As the species tends to occupy rock outcrops and paddock edges, it is

anticipated that such protection measures are unlikely to significantly affect grazing activities.

8.3.5 Gas pipeline construction

Five Z. granulata sites (Zg38, Zg41, Zg89, Zg95 and Zg96) were impacted by the construction of the Eastern Gas Pipeline in early 2000. The Department of Land and Water Conservation (now DIPNR) approved the removal of approximately 400 of the 600 Z. granulata plants that occupied the pipeline easement during construction work. The number of plants that were actually removed is unclear however, as problems with the on-site identification and delineation of environmentally sensitive areas were observed during construction work (S. Nally, DEC, pers. comm.).

Under the conditions of approval for the project, the pipeline operator (Duke Energy) is required to restore habitat at these sites to a similar or better condition than prior to disturbance, and to restore Z. granulata numbers to pre-clearing levels or greater.

8.3.6 Road construction

One of the five proposed routes for the Princes Highway upgrade between Gerringong and Berry (the North Saddle Corridor) will pass through a rainforest remnant that contains two sites (Zg87 and Zg88) that have been described as containing more than 1000 plants each (Muston & Associates 1991). The RTA is yet to determine its preferred route for this section of the highway (Chris Cleary, RTA, pers. comm.).

Under statutory environmental impact assessment processes, the RTA is required to consider the direct and indirect impacts of the proposed road upgrade on Z. granulata, in addition to Daphnandra sp C Illawarra, Illawarra Subtropical Rainforest and any other threatened species, populations or ecological communities that occur in that area.

The construction of the North Kiama By-Pass section of the Princes Highway will result in the removal of 36 Z. granulata plants from Tabbagong Forest (Robinson 1999).

8.3.7 Weed invasion

Weed invasion threatens a large proportion of Z. granulata sites (M. Bremner, DEC, pers. comm.; Robinson 1999; Sharma & Young 2001). Lantana (Lantana camara) is the most commonly recorded weed species at these sites and, along with Kikuyu (Pennisetum clandestinum) and African Olive (Olea europaea ssp. africana), is considered to be one of the most important weeds requiring management (Mills & Jakeman 1993). Bitou Bush (Chrysanthemoides monilifera ssp. rotunda) occurs in close proximity to Z. granulata at Bass Point (Zg27 and Zg28), where it is being actively managed (M. Bremner, DEC, pers. comm.).

The management of weeds at Z. granulata sites requires targeted bush regeneration efforts. These efforts should aim to restore, maintain and expand suitable habitat for the species. Mechanical weed control methods should be avoided at Z. granulata sites unless they are a component of a priority research project identified in Section 8.2.

8.3.8 Roadside and dry stone wall maintenance

Eleven Z. granulata sites occur, at least partially, on road verges that are managed by Kiama Municipal Council. At some of these sites, the species has been impacted by activities associated with roadside and dry stone wall maintenance, including slashing and spraying with herbicide. In addition to physically damaging Z. granulata plants, these activities have damaged or removed regenerating habitat (M. Bremner, DEC, pers. comm.).

Kiama Municipal Council has prepared a management plan that outlines measures to protect

Z. granulata plants at two roadside sites (Zg66 and Zg67). A similar plan is required to protect and manage other roadside sites within the LGA through the creation of buffer zones around individual plants and the regeneration of habitat where groups of plants are located.

8.3.9 Rubbish dumping

Dumped rubbish including green waste, dog faeces, household rubbish, construction materials and old cars has been observed at a number of Z. granulata sites (M. Bremner, DEC, pers. comm.). The dumping of these materials has the potential to damage Z. granulata plants and degrade its habitat through burial, physical damage and soil compaction. Rubbish dumping also has the potential to introduce weed propagules and pathogens to a site, and encourage weed growth by altering pH and nutrient levels in the soil.

The removal of dumped rubbish and the education of landholders and neighbours through letterbox drops, media articles and signage is considered to be the key to managing this threat.

8.3.10 Bushfire hazard reduction activities

In the absence of specific evidence to the contrary, it must be assumed that Z. granulata will be adversely impacted by frequent bushfire hazard reduction activities including prescribed burning and mechanical vegetation clearance.

As a consequence of our limited knowledge of the fire ecology of the species (see Section 6.5), the fire intervals recommended for Z. granulata are based

on the vegetation formations that are present at each site (see Table 12). A minimum fire interval of ten years has been attributed to sites that are located within vegetation formations where the natural fire frequency may be more frequent than this (eg sclerophyll grassy woodland). This is because ten years is considered to be a conservative minimum estimate of the time required for the species to reach reproductive maturity. Please note that, to allow time for seed production and the building of a soil seedbank, a period of three reproductive years should be added to each of these minimum fire intervals (NPWS 2002b).

Table 12: Fire interval guidelines for Z. granulata*
Vegetation formation Min. fire interval ** Max. fire interval Notes
Rainforest N/A N/A Fire should be avoided
Wet Sclerophyll forest 25 years 60 years Avoid crown fires at lower end of interval range
Semi-mesic grassy forest 10 years 50 years Avoid crown fires at lower end of interval range
Sclerophyll grassy woodland/ Shrubland 10 years 40 years Avoid crown fires at lower end of interval range
Shrubby dry sclerophyll forest 10 years 30 years Avoid crown fires at lower end of interval range

* adapted from NPWS 2002b
** add three productive years to the minimum fire interval to allow for seed production and the building of seedbank

The mechanical clearance of firebreaks through Z. granulata sites should be avoided unless it is a component of a priority research project identified in Section 8.2.

To enable the conservation requirements of the species to be considered by public authorities when planning bush fire hazard reduction work or issuing Bush Fire Hazard Reduction Certificates (BFHRC), the species should be placed on the Threatened Species Hazard Reduction List (TSHRL). This list has been prepared as part of the Bush Fire Environmental Assessment Code established by the Rural Fires and Environmental Assessment Amendment Act 2002.

Access to accurate location records (ie within 100 m accuracy) is required to ensure that the impact of managed bush fire hazard reduction activities on the species is minimised.

8.4 Prioritising the recovery effort

8.4.1 Relative conservation significance

To provide direction regarding where the limited resources associated with the recovery program for Z. granulata are best focused, it is useful to assess the relative conservation significance of individual Z. granulata sites. The relevant criteria for such an assessment include:

  • The number of plants that are present, including consideration of the soil seed bank;
  • The proportion of the population that is present at the site;
  • The location of the site in relation to the current distributional limits of the species;
  • The size, condition and connective importance of the habitat;
  • The uniqueness of the habitat; and
  • The management potential of site including the likelihood of ameliorating existing threatening processes.

Appendix 5 contains an interim assessment of the relative conservation significance of all known Z. granulata sites in relation to the above criteria. It should be noted however that this assessment is a broad brush assessment that is based on limited data. The assessment is not intended for use in statutory environmental impact assessment processes. Site specific assessments must be undertaken before decisions regarding the future management of individual sites are made.

A few broad assumptions can be made regarding some of the areas and sites that are likely to play a central role in the long-term survival of Z. granulata. The Dunmore Hills (ie the naturally vegetated hills between Oak Flats and the Jamberoo Valley) is one such area, as it contains extensive contiguous areas of good quality habitat for the species. A total of 27 Z. granulata sites have been recorded from the area, including two sites that have been described as containing thousands of individuals.

While the vast majority of Z. granulata sites occupy small, fragmented vegetation remnants that will require intensive active management to restore and maintain suitable habitat for the species in the long term, this is not the case for many of the sites that are located in the Dunmore Hills.

The sites in the Dunmore Hills may therefore play a central role in the long-term survival of the species. However, land-use conflicts with the quarry industry will need to be satisfactorily resolved for this to occur.

Other sites that are located in large areas of contiguous vegetation occur at Stockyard Mountain (Zg6), Upper Foxground (Zg84) and Upper Irwins Creek (Zg85). Sites where relatively large numbers of plants (>500) have been recorded occur at Albion Park (Zg4), Willow Gully (Zg60) and Toolijooa (Zg87 and Zg88).

8.5 Community awareness of the species

An increased awareness of Z. granulata is required to ensure that the species is appropriately considered in statutory environmental planning and impact assessment processes, and to facilitate the implementation of threat abatement works. The target groups for awareness raising initiatives are:

  • Private landholders;
  • Public authorities; and
  • The general community

The informed support of the private landholders whose land contains Z. granulata is essential to the success of the recovery program. Regular liaison with effected landholders and the publication of an annual newsletter detailing progress of the recovery program are two initiatives that will be established through this plan to encourage such support.

Public authorities with consent, determining or environmental planning responsibilities under the EP&A Act require an understanding of the species, particularly regarding location details, habitat requirements and sensitivity to impacts. Some public authorities also have an operational role (Rural Fire Service, Transgrid) in potential habitat for the species and as such, may inadvertently impact upon

Z. granulata sites.

Initiatives to assist public authorities in meeting their statutory obligations in relation to the consideration of Z. granulata in environmental impact assessment and land-use planning processes include:

  • The preparation and distribution of a species profile and environmental impact assessment guidelines; and
  • The verification and registration of site locations on the DEC Atlas of NSW Wildlife.

The third target audience for awareness raising initiatives is the general community. Initiatives that aim to enhance the social benefits of the recovery program amongst this target group include:

  • The preparation of an annual newsletter detailing the progress of the recovery program, which will be distributed to effected landholders, public authorities, community groups and interested individuals;
  • The preparation of press releases to highlight key recovery actions; and
  • The involvement of community members in the implementation of recovery actions.

8.6 Translocation and ex-situ conservation

8.6.1 Translocation

Translocation, defined as the deliberate transfer of plants or regenerative plant material from an ex-situ collection or natural population to a location in the wild, including existing or new sites or those where the taxon is now locally extinct (Vallee et al. 2004), is often raised as a possible method of conserving threatened flora. However, given the high cost and risk associated with the technique, translocation should only be considered as a last resort when all other management options are deemed inappropriate or have failed. As stated by Vallee et al. (2004), where possible, resources will be more effective when directed towards conserving existing populations in-situ through habitat protection and/or habitat rehabilitation measures and through the control of threatening processes.

Translocation is not considered to be necessary for the survival of Z. granulata as the in-situ conservation measures proposed in this recovery plan are expected to meet the conservation needs of the species. Further, primarily due to the uncertainty of success and the risks associated with translocation, the technique should not be considered by consent or determining authorities to be an appropriate means of ameliorating the impact of a proposal on the species (Vallee et al. 2004).

8.6.2 Ex-situ collection

The establishment of an ex-situ collection of Z. granulata seed, while not essential to the survival of the species, is considered to be a prudent contingency measure to protect against the loss of genetic material that may result from unexpected local extinctions. High priority sites for seed collection include the following:

  • Sites near the species distributional limits;
  • Sites containing unusual habitat for the species; and
  • Sites that form part of a population (as described in Table 11) that contains less than 100 plants.

8.7 Ability to recover

Recovery in the context of this plan, is to maintain the current endangered status of Z. granulata and prevent the taxon from moving to a less desirable conservation status (ie NSW TSC Act Schedule 1, Part 4, presumed extinct). The likelihood of recovery of Z. granulata in this context is high provided that the recovery actions outlined in this recovery plan are implemented, monitored and amended as required.