This review is particularly relevant to National reserve criteria 5 and 6 as outlined in Chapter 1 (box 1). The critical issues in this review are the importance of the Central Highlands in terms of the each taxon’s overall Australian distribution and the tenure of the population of each taxon in the Central Highlands.
Further issues relate to the viability of reserved populations, their replication within the reserve system (both in the Central Highlands and throughout their distribution), and the representativeness of the range of variants (if any) which may occur. This has only been undertaken for taxa listed under the FFG Act or ESP Act.
The approach used in this review differs from that employed in the East Gippsland Comprehensive Regional Assessment, where database records were intersected with maps of land tenure using a geographic information system (GIS) to produce percentages of records by land tenure. This approach was limited in that it did not account for variation in the size of sub-populations or for multiple records from the same sub-population, nor did it take account of biases in the data available for each species. It also has not identified historical records (eg. herbarium specimens) for which the source populations are now extinct. This factor is particularly important when dealing with an area such as the Central Highlands, where clearing has eliminated large areas of native vegetation.
This review is based on a qualitative rather than quantitative analysis, largely due to the lack of accurate, verified information on the current size and location of populations. It relies on a combination of recent records and judgement by experts. Each species was evaluated according to the proportion of its Australian distribution that occurs within the Central Highlands (0-25%, 25-50%, 50-75%, 75-100%), and the tenure of the land on which the largest proportion of its Central Highlands population (in terms of individuals rather than area or number of sub-populations) and the next largest proportion of its Central Highlands population occurred.
Of the 67 species being considered, 25 had more than 25% of their geographic range within the Central Highlands. Of these, 11 occurred wholly within, or had the largest proportion of their Central Highlands population within, biological conservation reserves.
Ten species had the largest proportion of their Central Highlands population on other public land, where the risk posed by permanent clearing is very low. Of these, eight had the next largest proportion of their Central Highlands population in biological conservation reserves. The remaining two species occurred either wholly on other public land, or with minor occurrences on private land.
Of the species with most or all of their Central Highlands population on other public land, rainforest or riparian species such as Oxalis magellanica, Carex alsophila and Wittsteinia vacciniacea are generally protected by the rainforest or stream buffer prescriptions, while Astelia australiana is the subject of species-specific prescriptions, including the protection of three sub-catchments in the Special Protection Zone of State forest.
Three species, Amphibromus pithogastris, Caladenia flavovirens, and Senecio laticostatus are confirmed only on private land in the Central Highlands. One species, Caladenia rosella, has the largest proportion of its Central Highlands population on private land and the next largest proportion in a conservation reserve.
Of the 42 species for which the Central Highlands contains less than 25% of their geographic range, eleven had the largest proportion of their Central Highlands population within biological conservation reserves. A further four species had the largest proportion of their Central Highlands population on other public land plus the next largest proportion in biological conservation reserves. Thirteen species were known only from other public land, three had the largest proportion of their population on other public land plus minor occurrences on private land.
Eight species only occurred on private land (Caladenia concolor, Eucalyptus strzeleckii, Lomandra longifolia ssp. exilis, Acacia howittii, Burnettia cuneata, Desmodium varians, Carex tasmanica and Cullen tenax), while a further three had the largest proportion of their population on private land plus minor occurrences on public land (Epilobium pallidiflorum, Eucalyptus yarraensis and Spiranthes sinensis).
The viability, replication and representativeness of the reserved populations of FFG and/or ESP listed taxa may be summarised as follows: the reserved sub-population of Caladenia rosellaconsists of a single location, contains very few individuals, exhibits low recruitment and is prone to ongoing threats. The reserved sub-populations of Eucalyptus crenulata include the majority of naturally-occurring individuals. Poor recruitment and habitat management continue to present management challenges, but there is no evidence to suggest that the sub-populations are not viable. The reserved sub-populations of Grevillea barklyana ssp. barklyana appear to be viable, and exist as several discrete stands. Recruitment appears adequate. The single reserved population of Phebalium wilsonii constitutes the entire known population of this species, but appears viable, comprising hundreds of individuals and showing evidence of recruitment. No information on population size and recruitment is available for Thismia rodwayi.
5.2.4 Vulnerability assessment
The vulnerability assessment is designed to identify those rare or threatened plants that are at greatest risk of further significant decline and extinction as a result of activities, ongoing threatening processes and catastrophic events in the Central Highlands. Note that this assessment is confined to each taxon’s Central Highlands distribution, and does not necessarily accord with its overall vulnerability, which is generally reflected by its status at a national or statewide level (see Table 5.1).
Where reliable information on the demography of rare or threatened plants is available, application of quantitative criteria such as those developed by the IUCN (IUCN 1994) to assign threat status is the most appropriate for a vulnerability analysis. In the absence of such information, estimation and qualitative judgements can be used, but will necessarily deliver a less reliable result.
For each of the rare or threatened taxa included in this review, available information for the Central Highlands has been collated and classified as follows:
Distribution pattern - taxa were classified as localised if their continuing presence was confirmed from fewer than 3 locations, or if their area of occupancy was less than 10km2. Otherwise they were classified as widespread, or unknown, if insufficient information was available.
Distribution trend - the trend of distribution over the last 10 years is classified as stable, suspected contraction, demonstrated contraction, suspected expansion or demonstrated expansion, based on database records, expert opinion and the literature.
Habitat breadth - taxa restricted to one habitat type were classified as narrow, taxa occurring in more than one habitat type were classified as broad.
Number of sub-populations - an estimate of the number of sub-populations (as opposed to the number of records, which may reflect repeated sampling, or a lack of sampling) was classified into orders of magnitude: <10, 10-100, 100-1,000, 1,000-10,000, >10,000.
Number of individuals - an estimate of the number of individual plants was classified into orders of magnitude: <10, 10-100, 100-1,000, 1,000-10,000, >10,000.
Population trend - the trend of population is classified as stable, suspected decline, demonstrated decline, suspected increase or demonstrated increase, based on database records, expert opinion and the literature.
Population variability - taxa whose population size fluctuates significantly are classified as high, taxa whose population size remains more or less stable are classified as low, based on expert opinion. In cases such as many of the terrestrial orchids, observed variability may be a function of season, when plants are dormant.
Longevity - an estimate of the average longevity of individuals of each taxon, classified into <1 year, 1-5 years, 5-10 years, 10-50 years, >50 years.
Reproductive output - taxa are classified as having high or low effective reproduction (ie. achieving germination and establishment as juveniles under normal conditions, rather than seed production alone) based on qualitative inferences regarding age of reproductive maturity, frequency of flowering, quantity of seed production, observed recruitment and observed vegetative spread, where relevant.
The results of this assessment are presented in Table 5,2. As can be seen, a large number of gaps remain for many attributes and for many species.
Vulnerability may be seen as a function of a number of variables, which alone or together may increase the risk of a taxon experiencing further decline, possibly to the point of extinction in the wild. Fundamentally, a taxon’s probability of survival (and conversely extinction) depend on its current population size, the extent to which it is threatened and its capacity to reproduce.
The significance of population size is in the immediate security that a large population size may afford from loss due to catastrophic events, either natural or human-induced. Additional protection is afforded where a population is comprised of several geographically isolated sub-populations, which serves to reduce the risk of catastrophic loss. In general, large population size also provides a greater source of genetic variability and reduced risk of inbreeding depression, increasing the evolutionary potential of the taxon and its responsiveness to environmental changes. However, plant populations do not necessarily follow these “rules”, as the greater variety of breeding systems and genetic systems, and the capacity for vegetative reproduction in many taxa, introduce additional variables.
However, overall population size is significant for most plant taxa. From the table, the taxa at most risk due to small population size are Amphibromus pithogastris, Caladenia concolor, Caladenia rosella, Lepidium hyssopifolium, Lindsaea microphylla, Lomandra longifolia ssp. exilis, Prasophyllum lindleyanum, Thismia rodwayi and Tmesipteris elongata ssp. elongata. Taxa at most risk due to low numbers of sub-populations are Acacia howittii, Amphibromus pithogastris, Asplenium terrestre ssp. terrestre, Beyeria viscosa, Bracteantha sp. aff. subundulata, Burnettia cuneata, Caladenia concolor, Caladenia flavovirens, Caladenia lindleyana, Caladenia rosella, Carex tasmanica, Coprosma moorei, Cullen tenax, Cyathea cunninghamii, Epacris coriacea, Epacris glacialis, Erigeron pappocromus var. oblongatus, Eucalyptus alligatrix, Eucalyptus crenulata, Eucalyptus neglecta, Eucalyptus pauciflora ssp. acerina, Eucalyptus strzeleckii, Euchiton umbricolus, Fimbristylis velata, Gahnia grandis, Huperzia varia, Hypsela tridens, Juncus antarcticus, Lepidium hyssopifolium, Lindsaea microphylla, Lomandra longifolia ssp. exilis, Mitrasacme montana, Monotoca oreophila, Ozothamnus rogersianus, Phebalium wilsonii, Poa labillardieri var. acris, Prasophyllum lindleyanum, Pteris comans, Pterostylis grandiflora, Richea victoriana, Senecio laticostatus, Senecio macrocarpus, Spiranthes sinensis, Taraxacum aristum, Thelymitra circumsepta, Thismia rodwayi, Tmesipteris elongata ssp. elongata and Tmesipteris ovata. High population variability also increases risk of extinction, as it tends to be associated with taxa whose life histories or reproductive strategies are based around pulses of reproduction, occurring either periodically or sporadically, often in response to environmental stimuli such as fire. To use a disturbance coloniser such as Lepidium hyssopifolium as an example, a short life span and reliance on soil stored seed for recruitment following disturbance renders this species vulnerable to a natural or imposed change in site conditions which prevents the necessary disturbance for a period greater than the effective life span of the soil stored seed. Taxa exhibiting high population variability are L. hyssopifolium and Pultenaea weindorferi. Other factors related to population size and extent are the pattern of distribution and breadth of habitat. Of the 66 rare or threatened plants assessed, 41 display a localised distribution pattern and occupy a narrow range of habitats.
Changes, particularly declines, in both the size of populations and the extent of their distribution is usually an indication that threatening processes are acting on the taxon. While some declines may be part of natural, cyclic variation, most are assumed to be part of the extinction process, and attributable to environmental changes and human disturbances since European settlement.
Taxa whose distribution has been demonstrated to have declined, or is suspected to have declined, are Lepidium hyssopifolium, Eucalyptus crenulata, Cyathea cunninghamii, Pultenaea weindorferi, Amphibromus pithogastris, Caladenia rosella, Carex tasmanica, Bracteantha sp. aff. subundulata, Caladenia concolor, Caladenia flavovirens, Caladenia lindleyana and Cullen tenax.
Taxa whose population size has been demonstrated to have declined, or is suspected to have declined, are Lepidium hyssopifolium, Eucalyptus crenulata, Pultenaea weindorferi, Cyathea cunninghamii, Amphibromus pithogastris, Caladenia rosella, Carex tasmanica, Gahnia grandis, Senecio macrocarpus and Epilobium pallidiflorum. Longevity in plants tends to be associated with a life history strategy based on resisting or tolerating the range of environmental conditions which may occur (including cyclic variation and stochastic events of climate, fire, predation and disease). Longevity therefore affords some additional security from rapid decline and extinction (especially during relatively benign environmental conditions) when compared to relatively short-lived taxa, but only if reproduction and recruitment is sufficient to compensate for mortality. Relatively short-lived taxa (1-10 years) include Carex tasmanica, Epilobium pallidiflorum, Cullen tenax, Carex alsophila, Lepidium hyssopifolium and Brachyscome obovata. Relatively long-lived taxa include Eucalyptus crenulata, Cyathea cunninghamii, Grevillea barklyana ssp. barklyana, Persoonia arborea, Eucalyptus strzeleckii, Eucalyptus yarraensis, Eucalyptus neglecta, Phebalium wilsonii, Eucalyptus alligatrix and Eucalyptus pauciflora ssp. acerina.
Reproductive output is considered to be low in Astelia australiana (sporadic flowering with poor seed set, although its ability to reproduce vegetatively may compensate), Cyathea cunninghamii and Persoonia arborea (both appearing to reach reproductive maturity only at advanced age).
While the preceding discussion indicates that a large number of taxa exhibit one or more of the characteristics of vulnerability, the highest priority should be given to taxa whose populations are small and declining further, with receding or degrading habitat and with little evidence of recruitment. Included in this category are Caladenia rosella (other Caladenia species could also be included) Carex tasmanica, Amphibromus pithogastris, Cullen tenax, Cyathea cunninghamii, Lepidium hyssopifolium and Senecio macrocarpus. Species dependent on Cool Temperate Rainforest are also of high priority given its sensitivity to environmental changes since European settlement, for example fire frequency.
Table 5.2: Vulnerability analysis for Central Highlands rare or threatened plants
Note: In this table, a dash (-) indicates that no information was available.
5.2.5 Management review
Both the Commonwealth Endangered Species Protection Act (ESP Act) and the Victorian Flora and Fauna Guarantee Act (FFG Act) include provisions for the preparation of management plans for listed taxa. Table 5.3 summarises the status of management planning for Central Highlands rare or threatened plants. Recovery Plans and Action Statements outline the actions necessary to maximise the long-term prospects of survival for the species in the wild. It should be noted that the implementation of management actions is dependent on available resourcing and priorities within and between species.
Table 5.3 : Status of management planning for Central Highlands rare or threatened plants.
Recovery Plan under the ESP Act
Action Statement under the FFG Act
draft research plan completed
published and implemented
Bracteantha sp. aff. subundulata
Bracteantha sp. aff. subundulata
published and implemented
Grevillea barklyana spp. barklyana
Note: * This recovery plan has yet to be formally approved by the Commonwealth Environment Minister
Of the 67 species considered in this review, only three are the subject of regular monitoring to determine population trends and evaluate threats across most or all populations. These species are Astelia australiana, Caladenia rosella and Eucalyptus crenulata. Other readily recognisable or high profile species such as Phebalium wilsonii, Grevillea barklyana ssp barklyana, Cyathea cunninghamii and Pultenaea weindorferi are the subject of opportunistic monitoring by professional botanists or amateur field naturalists.
The Department of Natural Resources and Environment has developed a simple monitoring form for rare or threatened plants populations. It is envisaged that the use of this form and the database in which the data collected are stored will expand to the point where the major populations of all threatened species will be regularly monitored, either by field staff, community groups or botanists.
Active habitat management
Active habitat management, in the form of environmental weed control, exclusion of predators or browsers and ecological burning, is the most common form of rare or threatened plant management being implemented for species whose habitat is degrading or where direct external threats are operating. Among the species considered in this review, only Eucalyptus crenulata, Cyathea cunninghamii, Astelia australiana and Caladenia rosella are the subject of active habitat management designed to improve their survival and recruitment. Other rare or threatened plants may benefit indirectly from active, landscape-scale threat management.
Active population management
Where populations of threatened plants have declined to critical levels, active population management techniques, such as population reinforcement, reintroduction, translocation and artificial pollination are sometimes recommended. Of the species considered in this review, only Eucalyptus crenulata and Caladenia rosella have been the subject of such techniques.