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Pherosphaera hookeriana | |
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Pherosphaera hookeriana | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Gymnospermae |
Division: | Pinophyta |
Class: | Pinopsida |
Order: | Araucariales |
Family: | Podocarpaceae |
Genus: | Pherosphaera |
Species: | P. hookeriana |
Binomial name | |
Pherosphaera hookeriana W.Archer bis | |
Pherosphaera hookeriana, or Mount Mawson pine (previously known as Microstrobos niphophilus), is a dwarf conifer endemic to Tasmania, at altitudes above 600 meters. There are roughly 30 known sites, with population numbers in the tens of thousands. The species occurs in a range of habitats typically in areas near water bodies, mostly on dolerite derived soils. The species is highly fire sensitive and an increase in fire events associated with climate change may lead to local extinction and fragmentation of habitat.
Pherosphaera hookeriana is a densely-branched erect shrub or small tree growing to heights of 5 meters, branches are often small and rigid with leaves arranged spirally and fully appressed to the stem. Individual leaves can measure up to 1.5 mm long, and 1 mm wide, leaves are thick, blunt and concave with a rounded keel. Male flowers form in compressed, terminal globular cones, ranging from 1–5 mm in diameter, with 8 to 15 fertile scales, each scale has two pollen sacs on the abaxial surface. Female flowers occur in cones on short branches that usually droop (hence the old common name). The flowers are globular, 2–4 mm long and have 3-8 fertile scales, with a single ovule on the upper surface of each. When the seed is ripe it has a hard, glossy brown coat and is approximately 1 mm in diameter (Curtis & Morris 1975, Hill 1998).
Pherosphaera hookeriana is a dwarf conifer that has been recorded to grow up to 5 meters, but in exposed and harsh environments it may only attain a height of 0.5 meters (Minchin 1983). The foliage of Pherosphaera hookeriana is well adapted to the high altitudinal ranges it occupies, with small imbricate scale leaves, the stomata are restricted to the adaxial surface and protected by a marginal leaf frill (Hill and Brodribb 1999). The species is generally dioecious, with the reproductive organs occurring on specialised leaves arranged in cone like structures. Pollen is wind dispersed and seed ripening occurs by late April (Wood & Rudman 2015). It is unclear if the plant produces seed annually or produces mass seed every few years (mast seeding). Germination appears to happen only rarely and is restricted to moist, shady areas. The seed is noted as having a dormant period, which could potentially result in a soil-stored seed bank with germination being staggered over several years. It is unknown how long the seed is viable in the soil for, but preliminary studies show that the seed requires warm stratification and then cold stratification to elicit germination; so the earliest it can take place is in the second spring/summer following dispersal (Wood & Rudman 2015). The seedlings superficially resemble small lycopods, with narrow spreading leaves. The seeds drop within a few meters of the parent plant. It has been suggested that dispersal over long distances via water is possible for plants occurring near lakes and rivers. Pherosphaera hookeriana may form extensive clonal colonies via vegetative growth (Fitzgerald 2011). Like most endemic alpine conifers to Tasmania, the growth rate of Pherosphaera hookeriana is extremely slow. Plants that have a stem diameter of 3–6 cm having an estimated age of 250–300 years on Mawson Plateau in Mt Field National Park (Minchin 1983) with the actual maximum ages likely exceeding 500 years. The time frame for plants to reach reproductive maturity is unknown, though there were observations of fruiting plants on the Tarn Shelf in Mt Field National Park in 2016 in areas that suffered fire damage in 1966. Pherosphaera hookeriana is one of only two species in the genus, and is one of the five taxa in the family Podocarpaceae with four being endemic to Tasmania (de Salas & Baker 2016). This species can be confused with the more widespread and often co-occurring Tasmanian endemic shrubby conifer, Diselma archeri .
Pherosphaera hookeriana is endemic to Tasmania's west, southwest and central plateau, the current distribution of the species is most likely to be a reflection of post-glacial expansion from refugia and subsequent fire events (Kirkpatrick & Dickinson 1984) Pherosphaera hookeriana exists in altitudinal ranges from 600 to 1300 meters above sea level in a wide range of habitats from alpine to Sphagnum bogs, the common element through the environments the species inhabits is the high soil moisture content and annual rainfall. Confirmed records indicate that the species ranges from the Walls of Jerusalem National Park in the north to Mt La Perouse in Southwest National Park (Tasmanian threatened species guide 2016) – about 12 kilometers from Tasmania's south coast. Most populations of the species occurs on soils derived from Jurassic dolerite, with an exception being a stand in Artichoke Valley near Frenchmans Cap, which grows on sedimentary deposits.
Mount Field National Park has long been recognized as the stronghold for the species with areas of coniferous heath being dominated or co-dominated by the species. There are approximately 30 known stands with an estimated population of 20,000 individuals. There is a high likelihood that stands of the species undiscovered, particularly in the Walls of Jerusalem National Park.
Pherosphaera hookeriana is listed under the old name Microstrobos niphophilus as vulnerable under the Tasmanian Threatened species protection act of 1995, after having its classification updated from rare in 2001. The chance of the whole species being lost in a single disaster is very unlikely, given its wide geographic range, however the chance of local extinction in individual stands or subpopulations appears to be increasing (the Lake Mackenzie fire in early 2016 is evidence of the threat fire poses to montane conifers). Populations at lower altitudes closer to more flammable vegetation communities are considered to be at extreme risk of fire damage over the coming decades. Another prominent issue is that anecdotal reports suggest that the rate of seedling germination and establishment is extremely low. The possibility that many of the stands of this species are clonal in combination with the breeding strategy, could potentially set a limit on viable seeds in some areas. Climate change and the trends towards a warmer climate, with a greater chance of extreme events such as drought and fires, are likely to have a direct and adverse effect on populations of Pherosphaera hookeriana. Severe declines or local extinctions in more susceptible regions are predicted to occur by the end of the century.
Nothofagus cunninghamii, commonly known as myrtle beech or Tasmanian myrtle, is the dominant species of cool temperate rainforests in Tasmania and Southern Victoria. It has low fire resistance and grows best in partial shade conditions.
Nothofagus gunnii, the tanglefoot or deciduous beech, is a deciduous shrub or small tree endemic to the highlands of Tasmania, Australia. It was described in 1847 by R.C Gunn N. gunnii is a small woody tree with a shrubby appearance known to grow up to 8 metres (26 ft). It lives only on mountains due to temperature limitations within the Tasmanian maritime climate and mainly grows at altitudes greater than 800 metres (2,600 ft) above sea level. It grows in alpine and sub-alpine regions in the central portions of the island. Though capable of reaching the size of a small tree, it is most common as a thick shrub or woody ground cover, hence its common name of "tanglefoot".
Diselma archeri is a species of plant of the family Cupressaceae and the sole species in the genus Diselma. It is endemic to the alpine regions of Tasmania's southwest and Central Highlands, on the western coast ranges and Lake St. Clair. It is a monotypic genus restricted to high altitude rainforest and moist alpine heathland. Its distribution mirrors very closely that of other endemic Tasmanian conifers Microcachrys tetragona and Pherosphaera hookeriana.
Athrotaxis cupressoides, commonly known as pencil pine, despite being a species of the family Cupressaceae and not a member of the pine family. Found either as an erect shrub or as a tree, this species is endemic to Tasmania, Australia. Trees can live for upwards of 1000 years, sustaining a very slow growth rate of approximately 12 mm in diameter per year.
Eucalyptus coccifera, commonly known as the Tasmanian snow gum, is a small to medium-sized tree endemic to Tasmania. It has smooth, grey and cream-coloured bark, elliptic to lance-shaped adult leaves, flower buds in groups of between three and nine, usually white flowers and conical, hemispherical or cup-shaped fruit.
Gaultheria hispida, commonly known as the copperleaf snowberry, is an endemic eudicot of Tasmania, Australia. It is an erect multi-branched shrub, that can be found in wet forests and alpine woodlands. Its berries appear snowy white and leaves are tipped with a copper tinge, hence the common name.
Anopterus glandulosus, commonly known as native laurel or Tasmanian laurel, is a species of shrub or small tree in the family Escalloniaceae. Endemic to south and southwestern Tasmania, A. glandulosus is widespread in the moist understoreys of Tasmanian temperate rainforests and wet sclerophyll forests from sea level to mountainous regions below 1,200 metres (3,937 ft) above sea level.
Gahnia grandis is a tussock-forming perennial plant found in southeastern mainland Australia and Tasmania.
Orites revolutus, also known as narrow-leaf orites, is a Tasmanian endemic plant species in the family Proteaceae. Scottish botanist Robert Brown formally described the species in Transactions of the Linnean Society of London in 1810 from a specimen collected at Lake St Clair. Abundant in alpine and subalpine heath, it is a small to medium shrub 0.5 to 1.5 m tall, with relatively small, blunt leaves with strongly revolute margins. The white flowers grow on terminal spikes during summer. Being proteaceaous, O. revolutus is likely to provide a substantial food source for nectivorous animal species within its range.
Agastachys odorata, commonly known as the white waratah or fragrant candlebush, is the sole member of the genus Agastachys in the protea family. It is an evergreen shrub to small tree and is endemic to the heaths and buttongrass sedgelands of western Tasmania.
Alpine vegetation refers to the zone of vegetation between the altitudinal limit for tree growth and the nival zone. Alpine zones in Tasmania can be difficult to classify owing to Tasmania's maritime climate limiting snow lie to short periods and the presence of a tree line that is not clearly defined.
Geum talbotianum, also known as the Tasmanian snowrose, is a perennial rosette herb endemic to Tasmania and confined to the high rocky places of Tasmania's Southern mountains.
Gonocarpus montanus is a perennial, terrestrial herb in the family Haloragacae. It is native to N.S.W, Victoria, Tasmania and New Zealand. Common names include mountain raspwort and mat raspwort. Its synonym is Haloragis montana.
Astelia alpina called pineapple grass, silver astelia, or perching lily is a commonly found species in alpine and subalpine areas of Tasmania and the Australian Alps. It is a perennial herb that typically dominates its environment by growing in dense clusters, called mats, in alpine bogs. There are two subspecies: Astelia alpina var. novae hollandiae from New South Wales and Victoria and Astelia alpina var. alpina endemic to Tasmania. Both subspecies appear very similar to each other. The species was originally described by Robert Brown.
The vegetation in Tasmania's alpine environments is predominately woody and shrub-like. One vegetation type is coniferous shrubbery, characterised by the gymnosperm species Microcachrys tetragona, Pherosphaera hookeriana, Podocarpus lawrencei, and Diselma archeri. Distribution of these species is relevant with abiotic factors including edaphic conditions and fire frequency, and increasingly, the threat of climate change towards species survival exists. Conservation and management of coniferous shrubbery are necessary considering that the paleoendemic species, Microcachrys,Pherosphaera and Diselma, have persisted in western Tasmanian environments for millions of years.
Chionogentias diemensis is a flowering herbaceous alpine plant in the family Gentianaceae, endemic to the island of Tasmania in Australia. It is commonly known as the Tasmanian mountain gentian. Chionogentias diemensis has been classified into two sub-species: the Tasmanian snow-gentian and the Ben Lomond snow-gentian.
The Tasmanian Central Highland forests is a temperate broadleaf and mixed forests ecoregion in Australia. It covers Tasmania's Central Highlands region.
Olearia ledifolia, commonly known as rock daisy bush, is a species of flowering plant of the family Asteraceae. It is endemic to Tasmania and found at higher altitudes where it grows as a low, compact bush with tough, leathery leaves and small white and yellow daisy-like "flowers" in summer.
Euphrasia striata, commonly known as ‘shiny striped eyebright’ is an endemic Tasmanian species, which is a member of the Scrophulariaceae family. The distinctive purple striations on the petals, from which the name was derived, are characteristic of the species.
Euphrasia semipicta, commonly known as the Peninsular eyebright, flowering plant endemic to the Tasman Peninsula in south-eastern Tasmania/ luturwita.