Biodiversity Assessment Technical Report


APPENDIX E: Life history attributes of Threatened plant taxa



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APPENDIX E: Life history attributes of Threatened plant taxa

Notes on interpretation:



  1. The following species summaries include information about the number of records within the Central Highlands region and Victoria for each taxon. This information is automatically derived from NRE databases, and may include historical records of populations which are now extinct or repeated records from the same populations. They do not therefore represent an accurate measure of the number of extant populations.

  2. The distribution maps shown include only the distribution (based on 10 minute grids) within the Central Highlands region, and not beyond.

  3. The tables which indicate the relative importance of potential threats to the each taxon include ratings as follows: 1 equates to relatively low importance and 3 equates to relatively high importance.

Tall Astelia Astelia australiana

Family: Liliaceae

Description: A tall tussock-forming graminoid: robust, perennial herb with strap-like leaves arising from distinct tussocks. Foliage to two meters tall. The ribbed leaves are long (60-230 cm) and quite broad (4-10cm) with a shining upper surface and densely felted undersurface (Turner & Sydes 1995). Green or reddish flowers are borne on many-flowered open panicles. Seeds are contained within orange berries.

Conservation Status:

  • ROTAP: Vulnerable

  • VROTS: Vulnerable

  • ESP: Listed

  • FFG: Is listed, with an Action Statement



no of records in Victoria

Victorian range (km)

no of records in region

regional range (km)

% of Aust Majority

Tenure of largest proportion of Central Highlands population

Tenure of next largest proportion of Central Highlands population

45

279

37

41

75-100

other public land




Distribution: All but one of the twelve known colonies of Tall Astelia are within a relatively small area in the Powelltown-Beenak district of the Central Highlands. Astelia australiana is endemic to Victoria. The presumed habitat at European settlement was isolated and most is still present.

Habitat: The species occurs primarily in Cool Temperate Rainforest dominated by Myrtle Beech (Nothofagus cunninghamii), with two colonies in Riparian Scrub dominated by Scented Paperbark (Melaleuca squarrosa) and Woolly Tea-tree (Leptospermum lanigerum). It occurs in gullies on undulating, upland plateaus on soils that are generally moist.

Reproduction: Little is known of the reproductive biology of Tall Astelia: it flowers and sets seed infrequently. Plants predominantly flower from October to December. Pollination is by flies and it is likely that birds and mammals are the evolved dispersers of the seeds (Turner and Sydes 1995). The species is mainly reliant on vegetative reproduction via a horizontal stem. This habit of Tall Astelia leads to the formation of large swards or colonies that may be a single genetic individual (Turner & Sydes 1995). Plants may re-establish following the dispersal of individuals downstream in flood conditions (Turner et al 1996). Plants are long-lived perennials, surviving for more than 50 years. The species is an obligate seed regenerator: all (or nearly all) plants are killed by fire, and regeneration is solely from seed, often only via invasion from unburnt sites. Tall Astelia is not thought to be dependent on disturbance for regeneration.
ISSUES & STATUS IN CENTRAL HIGHLANDS

Threatening processes: Tall Astelia has been much reduced by successive forest fires (Willis 1970). Wildfire represents the single most important threat to the survival of Cool Temperate Rainforest in Victoria (Howard 1981). Tall Astelia now occurs almost exclusively in drainage lines flanked by 1939 regrowth forest (Turner & Sydes 1995). The loss of the Cool Temperate Rainforest habitat through fire or other major disturbance is likely to lead to loss of colonies, furthermore, because ten of the twelve colonies are in a relatively small area around Dick Hill, south of Powelltown, the species is particularly vulnerable to local catastrophic events. Timber harvesting operations could alter sediment loads adversely affecting Tall Astelia and its habitat (Campbell & Doeg 1989). Regeneration burns extending beyond coupe boundaries could be detrimental to colonies and road construction has increased exposure, promoting other competing plants, in one case.


Threat

Rating

Threat

Rating

PLANT COLLECTION

1

WEED INVASION

2

RECREATIONAL DAMAGE

1

SMALL POPULATION SIZE

2

WILDFIRE

3

TIMBER HARVESTING

1

ALTERED HYDROLOGY

2

SOIL EROSION

1

DISEASE (Myrtle wilt)

1

LACK OF RECRUITMENT

1


Reservation: All colonies in the Central Highlands are within State Forest in which hardwood production is a major land use. Timber harvesting has been excluded from one subcatchment in each of the major watersheds in which Tall Astelia occurs. These areas are Bjorksten Creek (La Trobe watershed), Seven Acre Creek upstream from Bunyip Road (Bunyip watershed), and Tomahawk Creek tributary (Yarra watershed).

Management: The Action Statement for Tall Astelia includes a series of prescriptions designed to protect colonies and their habitat. Detailed monitoring has been undertaken and a study of genetic variability has been completed. Further research focusing on the reproductive biology and ecology of Tall Astelia is desirable.
Crimson Spider Orchid Caladenia concolor

Family: Orchidaceae

Description: A perennial herb to 40cm high with a globose tuberoid, the underground stem and tuberoids are invested in a fibrous tunic. One or two flowers on a slender erect hairy stem.

Conservation Status:

  • ROTAP: vulnerable

  • VROTS: vulnerable

  • ESP: Not listed

  • FFG: Has been nominated



no of records in Victoria

Victorian range (km)

no of records in region

regional range (km)

% of Aust Majority

Tenure of largest proportion of Central Highlands population

Tenure of next largest proportion of Central Highlands population

11

447

3

40

0-25

private land

conservation reserve


Distribution: Caladenia concolor is currently known from the council-owned Tyaak Reserve approximately 10km east of Broadford, the Boomers Reserve near Eltham and private land in the Cottlesbridge area.

Habitat: Lowlands, Sandy Outwash Plains and Dunes on upper slopes. Caladenia concolor occurs in woodlands or open forest with a grassy or dry sclerophyll (shrubby) understorey on well-drained loamy, sandy or gravelly soils. Sites are broadly of the Box-Ironbark alliance.

Reproduction: Caladenia concolor is a long-lived summer-dormant perennial herb. The tuberoid (‘tuber’) is dormant between late spring or early summer-and autumn when the solitary leaf appears above ground(late April-May). During the winter to spring growing season the plant produces one leaf, and if sufficiently large, a flower stem develops from the center of the leaf. The ‘mother’ or ‘current seasons’ tuberoid that produces the leaf and flower renews itself over the growing season to produce a ‘daughter’ tuberoid by which the plant survives over the next summer. The ‘mother’ tuberoid dies at the end of the summer. In this way plants potentially have somatic immortality. Flowers open in September and October and remain open, if not pollinated for 4-6 weeks. Pollination is by male thynid wasps. Flowers close a day or so after pollination and seed ripens and is shed 3-4 weeks later. Seeds are minute and very numerous. The seed is assumed to be short lived in nature (not beyond a year) so that there is no carryover from one season to the next. Reproduction is exclusively by seed. Germination occurs in early winter and is dependant on an obligatory mycorrhizal relationship formed with a free-living fungus that provides sugars to the developing seedling. This mycorrhizal relationship continues throughout the life of the plant, the fungus apparently re-infecting the orchid tissue each autumn.



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