Recovery plan for Spyridium obcordatum (Hook. f.) W.M. in Tasmania
Fiona Coates
Departments of Geography and Environmental Studies/Plant Science
University of Tasmania, August 1991
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Contents
- Disclaimer
- Acknowledgements
- 1.0 Executive Summary
- 2.0 Introduction
- 3.0 Recovery Plan
- 4.0 Implementation
- References
- Appendix 1: Implementation program for recovery of S. obcordatum
- Appendix 2: Budget for recovery of S. obcordatum
- Appendix 3: Distribution of S. obcordatum
Disclaimer
The opinions expressed in this plan are those of the author and do not represent the official view of either the Australian National Parks and Wildlife Service or the Tasmanian Department of Parks, Wildlife and Heritage. It has been prepared according to current knowledge of Spyridium obcordatum in Tasmania and therefore is subject to modification, should further knowledge of the species become apparent.
The format of the plan follows Butler et al. (1991) as closely as possible, as specified in the recovery plan task brief provided by the Tasmanian Department of Parks, Wildlife and Heritage, July 1991.
Acknowledgements
The assistance of Stephen Harris and Penny Wells during the preparation of this plan is gratefully acknowledged. Distribution records were supplied by Greg Stewart, Cindy Ong and Mick Brown.
1.0 EXECUTIVE SUMMARY
The aims of this recovery plan are as follows.
- 1.1.1 To reclassify Spyridium obcordatum (Hook. f.) W.M. Curtis from an endangered species rating of 2VCi to a rare species rating of 2RCa by the end of a 12 month fencing and monitoring project.
- 1.1.2 To place three adequate secure reserves for this species into the management control of the Department of Parks, Wildlife and Heritage (DPWH). In Tasmania a reserve is considered adequate if it is a World Heritage Area or a State Reserve that cannot be revoked without the approval of both houses of State Parliament.
- 1.1.3 To ensure that adequate self maintaining populations (of over 2,000 plants) are established by early 1993.
The main criteria are as follows.
- 1.2.1 Further research is needed into the ecology of the species, namely in areas such as the response of S. obcordatum to mechanical disturbance and fire. At present it is considered likely that regeneration by seed is disturbance dependent.
- 1.2.2 There is a need for two further secure reserves.
- 1.2.3 A conservative estimate of between 1,000 and 2,000 mature individuals is recommended in three State Reserves, as a viable population according to the criterion of Briggs & Leigh (1988).
- 1.2.4 The demographic character of populations as evidenced at present is retained.
- 1.2.5 In situ regeneration is preferred to the introduction of artificially propagated plants because: the necessary expertise and facilities are limited in Tasmania; nothing is known of plant establishment requirements such as the ability of introduced plants to withstand drought; a reintroduction program is unlikely to reveal any useful information regarding habitat management and species requirements; some of the sites have been the subject of arson in the past.
The main actions required are as follows.
- 1.3.1 Adequate funding to guarantee the success of the project should be secured.
- 1.3.2 Proposals for two further secure reserves are initiated.
- 1.3.3 One population is fenced for protection against native animal browsing.
- 1.3.4 Demographic data is collected regularly so that recovery can be accurately assessed.
- 1.3.5 Reassessment of the conservation status of S. obcordatum after 12 months.
The proposed budget for the project is $23,985, with $15,903 required in the first year and $8,082 required in the second year (appendix 2).
2.0 INTRODUCTION
The earliest known record of Spyridium obcordatum is a collection made by Ronald C. Gunn in November 1843, from Asbestos Hills in northern Tasmania (HO21356). It has since been recorded from 4 other areas in the West Tamar region. The Australian National Botanic Gardens has successfully cultivated the species from cuttings and incorporated plants into its Living Collections (Meredith & Richardson 1990).
Spyridium obcordatum is listed by Briggs & Leigh (1988) and derived its rare species rating of 2VCi from herbarium records and the known present distribution of the species. Since then, recent work has confirmed old records (prior to 1970). However it was also found that only one population of S. obcordatum is reserved and that this population consists of a mere 4 individuals. It is likely that past burning practice of frequent low intensity fires is responsible for the decline of S. obcordatum at this site and without appropriate management the species is likely to become extinct at Asbestos Range National Park within the next 10 years. At a further three sites where it occurs on private property, it is threatened with local extinction by housing developments or land clearance for agriculture. At three sites in State Forest populations are abundant, although heavily grazed by native animals and rabbits. High levels of mechanical disturbance as well as fire appear to have favoured S. obcordatum at this site (Coates 1991). A site on non-allocated Crown land near Port Sorell supports a small but robust colony.
This recovery plan aims to outline the means by which threatened populations of S. obcordatum can be protected, so that they can regenerate under favourable conditions in the future and warrant a rare species reclassification from vulnerable to rare.
Spyridium obcordatum belongs to the Rhamnaceae family, tribe Rhamneae. J. D. Hooker first described Cryptandra obcordatum in Flora Tasmaniae (1860: 71) from a specimen collected by Ronald Gunn from the Asbestos Hills (type citation 'Gunn 1249'). The species has since been illegitimately described as Spyridium serpyllaceum (Reisseck & F. Muell.). The name Spyridium obcordatum was published by Curtis (1970). The epithet 'obcordatum' refers to the leaf shape, which is characterized by a knotched apex. The taxonomic description (Curtis & Morris 1974: 117) is as follows:
A prostrate or decumbent shrub with numerous slender wiry branches spreading 15-40 cm. Leaves broadly obovate and very blunt or obcordate, 5-10 mm long, margins recurved, upper surface usually glabrous, lower surface white with dense covering of very short hairs. Flowers c. 3 mm in diameter in small dense heads, shortly stalked and approximate, each head with a floral leaf and surrounded by brown bracts about as long as the calyx. Receptacle and outer surface of the calyx lobes tomentose. Disk forming a raised ring within the stamens and round the ovary.
Reference specimens: Tas: Dans Hill, J. Jarman, 1979, HO 31403; Asbestos Range, M. Cameron, 1972, HO42105; Asbestos Hills, R.C. Gunn, 1843, HO21356; 1.5 km west of Hawley Beach, P. Collier, 1990, HO126250.
Species nomenclature for other taxa mentioned in the recovery plan follows Buchanan et al. (1988).
Spyridium obcordatum is a prostrate shrub with brittle, wiry branches. It's habit may be mat forming over flat ground, or trailing over embankments, between rocks or where otherwise protected from grazing. It has a thickening at the base of the main stem from which numerous branches arise. Spyridium obcordatum has glossy, bright green foliage and chestnut coloured wood.
Seeds are hard, light chestnut brown in colour with a rounded back and a shallowly keeled face. The testa is shiny and coriaceous, with a prominent aril. On average, seeds are 1.5 x 1.0 mm in dimension.
Herbarium records (HO, Qu. Vic. Mus., MEL, NSW, CBG) and current knowledge (Coates 1991) indicate that S. obcordatum is a localized endemic known from 4 locations in the west Tamar and Port Sorell areas on the north coast of Tasmania (appendix 3). It is reasonably conclusive that all populations known from historical records have been relocated within the last 2 years, except for the earliest record from Yorktown. Inspections of areas where S. obcordatum is likely to be found have also been made, but no further populations have been located. There are no records for the Bass Strait islands (P. Cullen, A.N.U., pers. comm.). All sites are within the 800 mm isohyet, at altitudes below 100 m.
The largest S. obcordatum population is known from State Forest at Dans Hill, near Beaconsfield. At this site there are three populations which are all likely to consist of more than 1,000 - 2,000 plants and are regenerating both vegetatively and by seed. At the Asbestos Range National Park, a small population consisting of 4 plants has been located. The Greens Beach population is reasonably large (no count carried out, but likely to be in excess of 1,000 plants) but is on private property and is directly threatened by a housing subdivision. Near Port Sorell, one small population consisting of 15 individuals occurs on Crown Land and nearby on private property a larger population is also potentially threatened by a proposed housing subdivision. Plants are generally large and mat forming, or have resprouted after damage from bulldozers. One further population at Barnes Hill (south of Dans Hill) is threatened by clearing (C. Ong, pers. comm.).
Spyridium obcordatum shows no geological preference within its range but is restricted at individual sites. It is most prolific on serpentinite at Dans Hill, where past disturbance from asbestos mining appears to have favoured its regeneration. It is absent from other geologies in the immediate vicinity including quartzite, limestone and ironstone, although this may relate to other environmental conditions such as shading from other plants, rather than specifically to geology (Coates 1991). Serpentine environments often support open vegetation types (Kruckeberg 1987). Elsewhere it is found on dolerite at Greens Beach and Port Sorell and Precambrian sandstone at Asbestos Range National Park.
Spyridium obcordatum is not confined to a specific vegetation community. At Dans Hill, it occurs in vegetation dominated by Eucalyptus amygdalina - E. viminalis or E. ovata woodland or open forest with an understorey of Allocasuarina littoralis. The third stratum is predominantly Pimelea nivea in sunnier spots or Epacris virgata in shadier areas, plus Correa reflexa and Gahnia grandis. The dominant ground layer species are S. obcordatum, Baeckea ramosissima and Lomandra longifolia. The ground is typically open and rocky and heavily grazed by rabbits and indigenous marsupials. The area has experienced high fire frequencies in the past, probably in the form of medium to high intensity burns. Other disturbances include mining, off road vehicles and rubbish dumping. Soils are reddish-brown to brown earths.
At Greens Beach S. obcordatum occurs on dolerite in Allocasuarina verticillata woodland with an understorey of low shrubs and graminoids such as Calytrix tetragona, Hibbertia sericea, Correa reflexa, Lomandra longifolia and Diplarrena moraea. There are also a diverse array of small sedges and herbs such as Centrolepis aristata, C. strigosa, Drosera peltata, Wahlenbergia gracilenta, Angianthus preissianus, Hydrocotyle callicarpa, Stylidium perpusillum and Crassula sieberana. Soils are light grey-brown to orange-brown to dark brown silty, sandy loam. The site is exposed to onshore winds which deposit fine sand grains.
On dolerite near Port Sorell the vegetation is also dominated by A. verticillata but with a grassy ground layer consisting of Stipa sp. and Poa sp., and with associated species Lepidosperma laterale, Dianella revoluta, Gonocarpus teucrioides, Viola hederacea, Comesperma volubile and Hibbertia sericea. This site is sheltered and has not been recently disturbed, including by fire.
Spyridium obcordatum is found in low open coastal heath dominated by Allocasuarina monilifera and Leptospermum scoparium at Asbestos Range National Park on Precambrian sandstone. Associated shrubs are Acacia myrtifolia, Baeckea ramosissima and Boronia parvifolia with emergent Lepidosperma concavum. S. obcordatum was found at the edge of an eroded walking track, on a moderately sloping hillside with a westerly aspect. The soil is light grey, fine silty loam with a hardpan at shallow depth.
Regeneration in S. obcordatum populations is from soil stored seed and is likely to be initiated after fire or mechanical soil disturbance. Otherwise there is only a low level of regeneration and those seedlings which do arise, are unlikely to survive because of heavy grazing pressure. Germination trials (Coates 1991 and unpub. data) suggest that temperatures such as those experienced during medium to hot intensity burns are most likely to promote germination. It is likely that the small population at Asbestos Range National Park is a direct result of a long history of cool burns, which have transformed the vegetation from coastal woodland to heathland, and subsequently to a plant community dominated by resprouting species. These may be competing with the remaining S. obcordatum population for light. Although S. obcordatum can resprout, rare species in the Rhamnaceae family appear to be relatively slow growing. It is likely that the seed bank has been depleted over time and there have been few recruits to the population due to soil reaching insufficient temperatures to trigger post fire germination.
Plants are able to resprout after grazing even when this may be severe. Where protected from animals, trailing branches are able to layer by producing adventitious roots at their nodes.
Flowers are insect pollinated and appear to be self-incompatible. All plants observed were healthy, with no evidence of pathogens.
Seed dispersal is poor but is probably aided by ants.
Spyridium obcordatum flowers between September and late October with most plants flowering in early October. Fruit development commences in early November and the majority of plants in a population have fruit developing by mid-November. Dispersal is from mid December to early January. The fruiting body consists of a capsule which separates into three fruitlets, each containing one seed. Annual seed production appears to vary. However, it is likely that this species is similar to most plants in this respect, with variation ascribed to yearly fluctuations in rainfall and temperature as numbers of seeds collected from plants during December 1990, after a relatively dry Spring were lower than the preceding year. Seed viability is high (on average 80%).
Shoot extension occurs during Spring and Summer, but maximum growth is during November to December. Leaves are produced throughout the year.
These are included in section 2.5. Vegetation supporting S. obcordatum is almost weed free, and those which do occur are mainly herbs or grasses such as Hypochoeris radicata, Vellereophyton dealbatum, Centaurium erythraea, Aira elegantissima and Vulpia bromoides. There are no indigenous vascular species which are specifically associated with S. obcordatum, however it is associated with the rare serpentine endemic Tetratheca gunni at Dans Hill and with the only Tasmanian mainland occurrence of Pandorea pandorana at Port Sorell.
Spyridium obcordatum is considered an endangered species for the following reasons.
- 2.9.1 It is a localized species endemic to Tasmania, where it is known from only 4 locations.
- 2.9.2 It is inadequately reserved. Only one small population (4 plants) occurs in a national park. Three populations which occur on private property are threatened by housing developments and land clearing, one small population (<15 plants) occurs on non-allocated Crown Land and three populations occur in State Forest.
- 2.9.3 It is unlikely that this species exists elsewhere in Tasmania and efforts to locate it in similar habitats have been without success.
No conservation efforts of a practical nature have been undertaken. A leaflet aimed at educating the residents of the Greens Beach housing development has been produced by the Tasmanian Department of Parks, Wildlife and Heritage and is soon to be distributed. A report by the same department soon to be published (Coates 1991) has recommended that practical conservation efforts should include the following.
- 2.10.1 The maintaining of a seed bank by the Royal Tasmanian Botanical Gardens and the Australian National Botanical Gardens.
- 2.10.2 The reservation of the non-allocated Crown Land block near Port Sorell.
- 2.10.3 The drawing up of a management plan for Dans Hill in conjunction with the State Forestry Commission.
- 2.10.4 The recovery of S. obcordatum at Asbestos Range National Park.
- 2.10.5 Legal protection for S. obcordatum
- 2.10.6 Botanical surveys be carried out prior to proposed developments within the range of S. obcordatum, which is also known to contain two other rare species.
- 2.10.7 The location of S. obcordatum in Asbestos Range National Park be made known to Rangers, Fire Protection Officers and Land Managers in the Department of Parks, Wildlife and Heritage, and the Senior Botanist should be consulted prior to any fuel reduction burns or other habitat modifying exercises being carried out.
- 2.10.8 A full botanical survey of Asbestos Range National Park be carried out and the locations of all rare species mapped.
3.0 RECOVERY PLAN
The recovery plan aims to outline means by which the conservation status of Spyridium obcordatum can be reclassified from 2VCi to 2RCa. This would mean a change in conservation status from restricted (geographic range <100km), vulnerable and inadequately reserved to restricted, rare but not threatened and adequately reserved according to the criteria of Briggs & Leigh (1988). This means that the species is 'known to be represented within a national park or other proclaimed reserve' (p. 9) where the total number of plants in a single population is at least 1,000. This should be achieved by an increase in the current numbers of individuals in two known populations and by increasing the numbers of populations which are reserved.
To achieve this the following will be necessary.
- 3.1.1 At the beginning of the project, seed should be collected and plants propagated so that in the future, a seed bank can be maintained in the form of a living collection in the Royal Tasmanian Botanical Gardens.
- 3.1.2 Two further populations are secured in State Reserves.
- 3.1.3 A fencing program aimed at promoting vegetative regeneration in one known population at Asbestos Range National park is implemented.
The species will be considered for reclassification when the following is achieved.
- 3.2.1 Three spatially well separated populations consisting of over 2,000 individuals of S. obcordatum are known from State reserves for which consent from both houses of Parliament is needed prior to revocation.
- 3.2.2 Populations consist of vigorous, mature plants which regularly flower and set seed.
- 3.2.3 The species is legally protected under State legislation.
- 3.2.4 The ecology of S. obcordatum in relation to fire and habitat disturbance is adequately understood, so that its degree of endangerment under existing environmental conditions can be more accurately assessed.
Progress on the recovery actions should be assessed after one year, at which time modifications to the above criteria might be necessary. Full recovery of the species is targeted for early 1993.
4.0 IMPLEMENTATION
- 4.1.1 Establish a working group whose task is to supervise rare species recovery. The group should consist of a small number of officers or representatives selected from organizations such as the DPWH, the Royal Tasmanian Botanical Gardens, the University of Tasmania and Greening Australia. The working group's responsibilities should include organising funding, overseeing all aspects of research and recovery and appointing a project officer and technical staff.
- 4.1.2 Initiate reserve proposals for two sites.
- 4.1.3 Collect seed from the Dans Hill populations and begin propagation of plants for a living collection at the Royal Tasmanian Botanical Gardens.
- 4.1.4 Conduct a further survey of the Badger Head area at Asbestos Range National Park.
- 4.1.5 Locate the known population within Asbestos Range National park (appendix 3) and erect a fence to protect it from browsing by native animals.
- 4.1.6 Collect demographic data at three monthly intervals, for 12 months.
- 4.1.7 Analyze data and reasses populations after one year.
The estimated cost is attached as appendix 2. All costs are in 1991 dollars.
- 4.3.1 The recovery plan will be administered by the DPWH.
- 4.3.2 Two further State Reserves so that S. obcordatum is reserved over its entire geological range. Recommended sites are non-allocated Crown Land near Port Sorell and State Forest at Dans Hill. The latter is a Recommended Area for Protection (Working Group for Forest Conservation 1990).
- No land purchasing schemes are needed. Procedures dealing with the reservation of land is the responsibility of the DPWH.
- 4.3.3 A project officer should be employed to carry out a further ecological survey at Asbestos Range National Park, collect seed, liaise with the RTBG, liaise with land managers, supervise fencing and collect data pertaining to population demography and recovery (appendix 1).
- 4.3.4 Demographic data should be collected at three monthly intervals. After one year, the population should be reassessed and a short report produced outlining the recovery progress.
- 4.3.5 Demographic data should include: the percentage projected foliage cover of vegetation; the distribution of S. obcordatum plants; germination; mortalites; growth and site specific disturbance events.
- 4.3.6 A simple fencing program at Asbestos Range is considered the most practical step towards recovery. The existing population is so small that vegetative recovery should precede any efforts to regenerate the population by seed. Populations recommended for reservation are in good condition, although the Port Sorell population is very small. However, the unpredictable character of dry sclerophyll environments, particularly where fire frequency is concerned, suggest that a 'leave be' policy is the best option for managing plants at these sites. Elsewhere, the decline of populations on private property may be arrested as a result of the distribution of DPWH educational literature specifically targeting S. obcordatum in these areas.
- 4.3.7 If there is no evidence of regeneration at Asbestos Range National Park after one year and no other populations are discovered, fencing should remain in place. It is unlikely that any appreciable seed bank exists at present and up to five years may be is needed before plants flower, set seed and replace seed stores. In the future, germination and subsequent seedling production is likely to occur only after either soil disturbance or fire, and trials to encourage this may be considered after the soil seed bank is replenished. Research on S. obcordatum currently being undertaken at the University of Tasmania may identify interventive management techniques.
REFERENCES
Buchanan, A.M., McGeary-Brown, A. & Orchard, A.E. (1989) A Census of the Vascular palnts of Tasmania. Tasmanian Herbarium Occasional Publication No. 2.
Butler, G., Richardson, M. & Gantner, W. (1991) Recovery Plan for Grevillea iaspicula Mc Gillivray (Wee Jasper grevillea). Australian National Botanical gardens, Canberra.
Coates, F. (1991) The Conservation Ecology and Management of Five Rare Species in the Rhamnaceae Family. Wildlife Division Scientific Report 91/3. Department of Parks, Wildlife and Heritage, Tasmania.
Curtis, W.M. (1970) Spyridium obcordatum (Hook. f.) W.M. Curtis, comb. nov. Vict. Nat 87, 251.
Curtis, W.M. & Morris, D.I. (1974) The Student's Flora of Tasmania Part 1. (2nd ed.) Government Printer Hobart.
Hooker, J.D. (1860) Botany of the Antarctic Voyage, III, Flora Tasmaniae. Lovell Reeve & Co., London.
Kruckeberg, A.K. (1987) Serpentine endemism and rarity. In: Conservation and Management of Rare and Endangered Plants (ed. T.S. Elias). The Californian Native Plant Society, Sacramento California.
Working Group for Forest Conservation (1990) Recommended Areas for Protection of Rainforest, Wet Eucalypt and Dry Sclerophyll Forest in Tasmania Forestry Commission Tasmania.
APPENDIX 1. Implementation program for recovery of S. obcordatum.
| 1991/2 | 1992/3 | |
| Seed collection, Site assessments, Establish living collection, Fencing and data collection | Dec-Feb | |
| Data collection | May | August November February |
| Data analysis and report | Feb/March | |
| Reassessment | March |
APPENDIX 2. Budget for recovery of S. obcordatum.
| 1991/2 | 1992/3 | ||
| Salaries | |||
| Project Officer (4 months temporary full time @ $30,000 per annum pro rata) | $10,000 | $2,500 | |
| then employed on contract for 12 days @ $284/day based on a $30,000 per annum salary pro rata) | $852 | $2,556 | |
| On costs (21%) | $2,100 | $600 | |
| Travel (vehicle hire: 4,800 km @ 49c/km) | $1,176 | $1,176 | |
| Camp allowance (15 nights @ $25/night) | $125 | $250 | |
| Miscellaneous expenses | $150 | $100 | |
| Propagation | $500 | $200 | |
| Fencing | |||
| Labour | $600 | ||
| Materials | $400 | ||
| Maintenance | $500 | ||
| Data analysis and report production | $200 | ||
| TOTAL | $15,903 | $8,082 |
APPENDIX 3. Distribution of S. obcordatum (see attached 1:100,000 land tenure map and 1:25,000 topographic maps)
1. Grid references for populations on dolerite (areas 1,3)
Tamar 1:100,000
599 441; 778 514
2. Grid references for populations on Serpentinite (area 4)
Tamar 1:100,000
805 395; 796 405; 790 413; 809 374
3. Grid references for populations on Precambrian sandstone (area 2)
Tamar 1:100,000
705 484
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