GLOBAL ECOLOGICAL ZONING FOR THE GLOBAL FOREST RESOURCES ASSESSMENT 2000
Figure 39. GEZ map for
Oceania.
Table 24. Global Ecological Zones of
Oceania.
Global Ecological
Zone
Surface area
Km2
% of total land area
Region
% of GEZ worldtotal
Tropical rain forest
481 313
5.6
3.3
Tropical moist deciduous forest
26 298
0.3
0.2
Tropical dry forest
468 003
5.5
6.3
Tropical shrubland
1 063 413
12.5
12.8
Tropical desert
0
0
0
Tropical mountain systems
71 204
0.8
1.6
Subtropical humid forest
281 176
3.3
6.0
Subtropical dry forest
123 342
1.4
7.8
Subtropical steppe
1 461 055
17.1
29.8
Subtropical desert
4 139 152
48.5
26.9
Subtropical mountain systems
0
0
0
Temperate oceanic forest
218 534
2.6
12.1
Temperate continental forest
0
0
0
Temperate steppe
0
0
0
Temperate desert
0
0
0
Temperate mountain systems
193 632
2.3
2.7
Total land area
8 527 122
99.9
Oceania comprises Australia, New Zealand, Papua New Guinea and the Pacific Islands (Micronesian, Melanesian and Polynesian Archipelagos). The descriptions of the Ecological Zones of Papua New Guinea are already dealt with under Asia. This country forms an ecological entity with the western half of the island of New Guinea, Irian Jaya, a province of Indonesia.
8.1 TROPICAL DOMAIN
8.1.1 Tropical rain forest (TAr)
In Oceania, the Pacific Islands and small patches in northeastern Australia (Queensland) constitute this Ecological Zone, in addition to a large portion of Papua New Guinea.
Climate
The climate of the Pacific Islands is dominated by the trade winds. These winds take up moisture over the ocean and most of the Islands have ample precipitation. The average annual precipitation generally varies between 1500 and 4000 mm and the dry season is not severe. However, abundance of rains depends on the relief and, in the case of relatively high islands, conditions on the leeward side may be fairly dry, locally less than 1000 mm. Mean temperature at sea level is about 23oC near the Tropics and 27oC at the equator. The difference in temperature between the between the hottest and the coolest month is small owing to the oceanic environment. Cyclonic disturbances, occurring generally at about the end of the warm season, mainly affect the western Pacific archipelagos (Melanesia, western Micronesia).
The coastal area of northeastern Australia has a tropical wet climate and receives the highest annual rainfall in Australia. It has a mean annual precipitation of 1500-2500 mm with some areas exceeding 4500 mm per year. The precipitation distribution exhibits a marked summer maximum, with the majority occurring from January to March. The mean annual temperature is around 23oC with summer mean maximum of around 30oC and winter maximum of 20-23oC degrees. Winter mean minimum temperatures are generally around 12-15oC.
Physiography
With the exception of New Caledonia, where varied sedimentary rocks are found, the oldest dating from the Permian, the Pacific Islands are relatively recent and almost entirely composed of volcanic rocks of basaltic or andesitic composition, dating from the Miocene to the present. Lava flows have been partly covered by limestone during the period when the volcanic deposits were below the ocean; subsequently, coral-reef terraces may have been raised by a relative decline of the sea level. Most of the high islands have a rugged relief which involves great heterogeneity of the microclimatological and edaphic conditions. Common soils include various types of ferralitic soils developed from acid volcanic rocks. Around active or recently extinct volcanoes (Hawaiian Islands, Samoa, Vanuata), there are raw mineral soils and andosoils. On the low coral islands and calcareous cliffs, rendzinas are commonly found.
The landscape of the Northeastern coast of Australia began to evolve into their present form during the latter part of the Tertiary. During the Pliocene strong block faulting broke up an ancient peneplain, uplifting the tablelands but causing subsidence of the coastal plain and continental shelf. These movements were accompanied by sporadic volcanism. Three types of rain forest soils can be distinguished: a) granitic soils on foothills and mountains; b) metamorphic soils derived from ancient shales which underlay the old peneplain and c) the basaltic soils mainly of the tablelands.
Vegetation
Pacific Islands
The rain forests of the tropical Pacific are generally evergreen. Their structure is comparable to that of the Indo-Malaya forests, with several synusia, but the flora of the dominant strata is often relatively poor.
Various types of rain forest at low and medium altitudes do occur, related to soil type. The tallest hardwood forests are found on deep volcanic soils. Height of the formations ranges from 30 to 45m. About a dozen big tree species (Calophyllum, Campnosperma, Dilenia, Elaeocarpus, Endospermum, Gmelina, Maranthes, Parinari, Schizomeria, Terminalia) are the main constituents of the main canopy, overtopped at long intervals by banyan figs (Ficus) and by Terminalia calamansanay. Trees with large buttresses are frequent, especially in the alluvial areas. Vines and epiphytes abound. In Vanuatu, Fiji and Samoa this forest type is somewhat lower (about 30 m) and floristic composition is slightly different. The New Caledonia hardwood forests are found mainly on soils derived from sandstone. The flora is totally different from that of the forests in other parts of Melanesia. Clusiaceae (Calophyllum, Montrouziera), Cunoniaceae, Myrtaceae, Myrtoideae, Proteaceae, Sapotaceae predominate in the upper stratum. On limestone of the atolls grows a poorer type of forest; trees are 15 to 25 m tall with some emergents. In certain special environments, (peaty soils, altitudinal margins of distribution) broad-leaved forests with a single species dominating the upper stratum are found. Examples are the Nothofagus forests in New Caledonia, linked to ultrabasics and mainly found at medium to high altitudes and the Metrosideros collina forests which is found throughout the tropical Pacific for instance as a pioneer vegetation on lava flows.
Coniferous forests, often mixed with broadleaved species, have a limited distribution throughout the Pacific. The coniferous trees belong to the Araucariaceae, Cupressaceae, Podocarpacea and Taxaceae.
Mangroves cover rather large areas in the Melanesian archipelagos and in the Caroline Islands. The forest can reach a height of 25 meters and the main constituents are Rhizophoraceae together with the genera Avicennia, Lumnitzera, Sonneratia and Xylocarpus.
Australia
Tropical rainforests constitute around 1 million hectares of Australias forests. They are generally clearly demarcated from the eucalypt forest in their mature successional state. However, many areas currently exist where Eucalyptus species such as E. grandis occur as emergents in the canopy. The forest canopy ranges from around 30 to 40 m high, with emergent trees up to 50 m. In floristic composition, they resemble the rainforests of Indo-Malaya, except for the complete absence of Dipterocarpaceae. However, there are a number of Australian endemics, which are often a major component of the emergent tree strata. They include species of Flindersia, Cardwellia, Musgravea, Placospermum, Buckinghamia, Darlingia, Backhousia, Blepharocarya, Castanospermum, Ceratopetalum and Doryphora. The presence of several primitive and restricted angiosperm genera – Idiospermum, Austrobaileya, Sphenostemon, Bubbia, Ostrearia, Neostrearia, Eupomatia and Galbulimima add a further distinctive character to the rainforests of the region. Comparison with other rainforests shows that the species richness of the forests is greater than tropical rainforests in Africa and the Americas but less than those in some parts of southeast Asia.
Local variation in forest types occur, related to soil type, slope etc. and is expressed in tree composition and forest structure. Specialised life forms such as vines, epiphytes and pachycauls are present in most communities. Vines are usually numerous and include several species of climbing palm (Calamus spp.). Palms, especially Archontophoenix alexandrae, Licuala ramsayi, Orania appendiculata and Linospadix spp. and tree ferns, mainly Cyathea spp. are often encountered in the mid to lower canopy. Epiphytic ferns and orchids can be conspicuous, especially at higher altitudes. In swamp forests, limited to the wettest part of the coastal zone Melaleuca viridiflora paperbark forest often occurs as the main canopy species along with numerous palms. In the lower strata Pandanus spp. and sedges are often encountered, as well as climbing ferns and pandans (Freycinetia spp.). In the more well drained lowland areas, medium layered woodlands and forest often occur which include Eucalyptus tereticornis, E. tessellaris, E. intermedia and E. pellita.
8.1.2 Tropical moist deciduous forest (TAwa)
Papua New Guinea is the only location in Oceania where this Ecological Zone is found and mapped. The zone is described under Asia. In Northern Australia and the Pacific Islands, little areas of this type of forest may be found, however they are to small to map and are being discussed under another Ecological Zone.
8.1.3 Tropical dry forest (TAwb)
This Ecological Zone is confined to the northern parts of Australia.
Climate
The northern tropics of Australia have a marked seasonal alternation in moisture conditions, with an intense drought lasting 6 to 8 months throughout the winter, followed by monsoon rainfall during the warmer months. The Ecological Zone receives an average annual precipitation of 1000-1400 mm with around 75 percent falling in the monsoon period between December and March. The lowest annual precipitation of around 800 mm occurs in the Eastern Kimberley region of Western Australia and the highest annual precipitation of around 1600 mm occurring at the top of Cape York in northern Queensland. Drought conditions prevail outside of the monsoon period with less than 10-20 mm monthly average precipitation from June to August in most areas. The mean annual temperature is around 27oC with a mean summer maximum of 33oC and winter maximum of 31oC. Average minimum temperatures during the monsoon period are around 23oC and winter average minimums are around 15oC.
Physiography
This Ecological Zone is has a generally low relief, below 200 m, with hills in the west (Kimberleys) and centre (Arnhem Plateau). Except for the hills, the terrain is flat to undulating. A number of distinct physiographic units can be distinguished. The Arnhem and Darwin Coasts are dominated by gently undulating plains and low plateaux. The dissected plateau of the North Kimberly includes mainly shallow sandy soils derived from Proterozoic siliceous sandstones and red and yellow earths derived from Proterozoic volcanics. The Arnhem Plateau is comprised of hilly to rugged terrain derived from Proterozoic sandstones. Deep, well drained sandy or gravelly soils, mainly Red and Yellow Earth predominate. Lithosols are common in the rugged hills.
Vegetation
The main natural vegetation covering this Ecological Zone is Eucalypt forest and woodland. Various types do occur, each characterized by different dominant Eucalyptus species. Only the main ones are described.
The Eucalyptus tetrodonta – E. miniata suballiance occurs mainly west of the Carpentaria Gulf on flat to undulating terrain with well-developed soils. This community forms open to closed forests to 30 m high in the wettest areas, or in the drier areas, mainly woodlands 10 30 m high. The two characteristic species usually occur in equal proportions, though either may be dominant or occur in pure stands. In the Kimberly region this alliance often occurs on shallow sandy soils and gives way to a Eucalyptus tectifica and E. grandiflora alliance on yellow and red earths. Callitris intratroopica, now mostly removed for timber, once formed local associations on deep sand, either in pure stands or in association with E. miniata. The understorey species vary with mean annual rainfall. In wetter areas the tall forests often have a lower tree layer, composed of other eucalypt species.
Characteristic of the wetter stands is a small tree or tall shrub layer of broadleaved, mesomorphic species many of which occur in the rainforests, small stands sometimes enclosed by the Eucalyptus forests. A few lianas occur and the herbaceous layer dominated by grasses, often 2 m high, which have become increasingly abundant following burning. In drier sites, including the climatically drier southern part of the Ecological Zone and ridges in the wetter areas, the communities are woodlands and mesomorphic shrubs are rare or absent. Xeromorphic shrubs are sometimes present, especially in the north where they may form a shrub layer of circa 2 m high. The grass layer is usually discontinuous. Similar Eucalypt forest and woodlands occur on the flat to undulating terrain of Cape York Peninsula (east side of the Carpentaria Gulf), with the main difference that Eucalyptus polycarpa replaces E. miniata as co-dominant.
Melaleuca forests occur throughout the Ecological Zone on damp or wet sites such as coastal or sub-coastal areas that dry out seasonally. Often these forests are narrow strips of dense pure stands, tens of meters wide, along streams and swamps. About 75 percent of the melaleuca forests in Northern Australia are large tracts of low woodland spread across estuarine plains and seasonal swamps. The dominant canopy species include Melaleuca dealbata, M. leucadendra, M. minutifolia and M. viridiflora.
Small patches of so-called semi-evergreen vine forests or monsoon forests occur along watercourses, around lagoons and on patches of soil fed by springs or runoff water from the uplands. They are best developed on the Arnhem Peninsula, with the largest areas on Melville Island. A high proportion of deciduous plants, chiefly the dominants, distinguishes this type of rainforest. The forest canopy reaches a height of circa 15 m, sometimes with emergents up to 20 m. The forests usually have two tree layers in wetter situations, one in the drier and a few species have buttressed trunks. Lianas are abundant but epiphytes are rare or absent
Along the muddy coasts of Northern Australia which receive tides of up to 10 m, mangrove forests occur, often with the following sequence of species (seaward to inland): a) pioneer outer zone of Sonneratia caseolaris, mostly 8 10 m high, with massive pneumatophores. On firmer substrate the outer fringe is dominated by Avicennia marina, forming forests up to 10 m high; b) Rhizophora forest dominated by R. stylosa, usually 6 12 high but up to 25 m on the most fertile soils; c) Bruguira gymnorhiza dominated zone, forming forests up to 30 m tall in the most favourable habitats (eastern Queensland); d) Ceriops tagal community, mostly some 6 m high, often very dense with the canopies interlacing; e) the inner zone, sometimes well developed with a variety of species, form a forest of 12 m high.
8.1.4 Tropical shrubland (TBSh)
This Ecological Zone is also confined to the Northern part of Australia and immediately follows the more humid coastal zones.
Climate
The semi-arid tropics of northern Australia have a marked seasonal variation in moisture conditions with a pronounced winter drought lasting 6 to 8 months followed by substantial monsoonal rainfall in the summer months. The Ecological Zone receives an average annual precipitation of 700 mm with around 350 mm in the southern Kimberley region in Western Australia to 1000 mm in the southern parts of Cape York in Queensland. Around 75 percent of the precipitation occurs during the monsoonal period between December and March, with drought conditions for the remainder of the year. The mean annual temperature is around 26oC with a mean summer maximum of 35oC and mean winter maximum of 30oC. The average minimum temperature during the monsoonal period is 23oC and 12oC during winter.
Physiography
The physiography of this Ecological Zone is rather diverse, stretching across the north of the continent and into central Queensland. It is comprised of 10 very distinct regions, 5 of which include:
The plains of the Gulf of Carpentaria, which are dominated by marine and terrestrial deposits.
The Einasleigh Uplands which is a 700 m high plateau immediately inland of Australias tropical rainforest derived uplifted Palaeozoic sediments, granites and basalts.
The Ord-Victoria Plains which are a mosaic of abrupt Proterozoic and Phanerozoic ranges mantled by shallow sandy soils; Cambrian volcanics that form extensive plains of dry calcareous soils and heavy cracking clays.
The Gulf Fall Uplands which form steep hills on Proterozoic and Palaeozoic sedimentary rocks and
The Northern Brigalow Belt, which is dominated by Permian and Devonian volcanics and sediments and numerous Tertiary deposits.
Vegetation
The natural vegetation of this Ecological Zone is largely Eucalypt forests and woodlands.
The Northern Kimberly is dominated by Eucalyptus tetrodonta, E. miniata forests and woodlands and in the southern Kimberly it is dominated by Eucalyptus bevifolia and E. setosa low woodlands and open woodlands.
The centre of the Ecological Zone within the Northern Territory is comprised mainly of Eucalypt woodlands and Acacia forests and woodlands. In the skeletal Cretaceous sandstones bloodwood species such as Eucalyptus terminalis low woodlands dominate along with E. bevifolia on the undulating plains. Eucalyptus brevifolia dominates large tracts of land west of the Carpentaria Plains, extending to the Indian Ocean. It often forms mosaics with other species, for instance E. tetradonta, E. dichromophloia, or E. pruinosa. In the drier south it adjoins the acacia woodlands and shrublands. The vegetation is open woodland reaching around 9 m in the wettest sites; in drier areas the trees are stunted. In the taller woodlands on deep sands, shrubs may occur. The herbaceous layer consists mainly of grasses and these become increasingly prominent as the vegetation becomes more open. Lance wood (Acacia shirleyi) is the most widespread of the central northern acacia woodlands. A. shirleyi is a tree to 18 m tall which forms low woodland in the drier parts of its range. The stands often intermingle with eucalypt woodlands. A grass layer is usually present.
In the eastern part of the zone, ironbark woodlands cover large areas in Queensland. Eucalyptus drepanophylla is the most common species and forms woodlands of 12 20 m tall. A few other eucalypts are confined to the alliance and many ecotonal associations occur, varying in physiognomy and species composition. The grass layer is always dense, with Bothriochloa ewartiana, Heteropogon contortus and Themeda australis as the main species. Another characteristic vegetation in this region are the boxes, medium height eucalypt woodlands in drier areas. The main species are Eucalyptus leptophleba, E. microneuro and E. normantonensis and they form open woodlands 7 to 15 m, sometimes up to 20 m in the wetter parts. These boxes have considerable economic importance as they all provide grazing for domestic stock. Callitris glauca, a common associate in some of the woodlands, is an important timber species. At the southern end of the Ecological Zone, silverleaf ironbark becomes dominant (Eucalyptus melanophloia), as does Callitris glauca and brigalow (Acacia harpophylla) with has now largely been cleared due to its natural preference for productive black soils which are also suitable for agriculture.
8.2 SUBTROPICAL DOMAIN
8.2.1 Subtropical humid forest (SCf)
The subtropical humid forest zone comprises the east coast of Australia, roughly between 23o and 35oS and North Island of New Zealand.
Climate
Australia
The coastal areas of southern Queensland and northern New South Wales have a sub-tropical humid climate with mild winters and hot summers. Mean annual precipitation across the region is 1100 mm, with areas on the Queensland/New South Wales border receiving in excess of 2200 mm and rain-shadow areas receiving as little as 700 mm annually. Precipitation is reasonably well distributed with most months receiving in excess of 70 mm of precipitation, although around 50 percent of the rain does fall between December and March, with summer precipitation increasing in the north. The mean annual temperature of the region is around 18oC with the northern extent 3 degrees hotter and the southern extent 2 degrees colder. Average summer maximum temperature is 26o to 29oC and average winter maximums range between 17o and 22oC. The average minimum temperatures during winter range between 3o and 7oC and average minimum summer temperatures range from 15o to 19oC.
New Zealand
The climate of North Island of New Zealand is strongly influenced by the ocean. Extremes of heat and cold are absent. The mean summer temperature is 16o 18oC and mean winter temperature around 10oC. Rainfall is high, rather regular over the island and ranges from around 1000 mm to more than 1500 mm (on the central plateau), with maxima during winter.
Physiography
Australia
In the north this Ecological Zone is composed of metamorphic and acid to basic volcanic hills and ranges, with extensive alluvial valleys and Quaternary coastal deposits including high dunes, coastal plains. In the south, which includes the Sydney Basin, it is comprised of Mesozoic sandstones and shales which dominate dissected plateaus which have developed skeletal sands and podzolics.
New Zealand
The land of North Island is rugged with a few isolated mountains. The center of the island is a volcanic plateau much of which is at an altitude of more than 600 m, but northwards gradually becoming lower, it extends to the Bay of Plenty. The extreme north of the island consists of a small, narrow much dissected tableland some 300 m high, formed of hard igneous and sedimentary rocks. An extensive plain of marine origin occupies the southwest of the island. River-formed gravel plains occur east and west of the main range. Yellow-brown soils of moderately low fertility predominate.
Vegetation
Australia
The dominant vegetation of this Ecological Zone is open Eucalypt forest which generally exceed 30 metres tall and can often reach 50 metres, while in the moist valley bottoms, warm temperate rainforests are the dominant life forms. The vegetation with the centre of this region is extremely diverse being the core of a major ecotone where northern species are at their southern limit and many southern species are ate their northern limit. There are also significant environmental gradients leading from the coast to the high mountain ranges that drive the distribution of a large range of forest communities.
In the north of the Ecological Zone the inland medium open Eucalypt forests are dominated by Eucalyptus tereticornis and Corymbia maculata (formally E. maculata), while the coastal forests are dominated by bloodwoods such as E. intermedia and E. acmenoides. Further to the west numerous rainshadows occur which are dominated by dry ironbark forests and woodlands comprised of E. crebra, E. fibrosa, E. tessellaris and E. melanophloia.
In the centre of the region, on the Queensland/ New South Wales border precipitation increases from around 1100 mm to approximately 2000 mm, where Australias warm temperate rainforest occur as the dominant forest type. Outside of this area it mainly occurs as narrow strips in the valley bottoms of Eucalypt forest. These rainforests become progressively richer floristically from south to north, as they mingle with the richer tropical rainforest. Coachwood (Ceratopetalum apetalum) characterizes the rainforests between lat 37o and 28oS and a number of communities occur, differentiated by habitat and presence of co-dominants. Co-dominant trees include Doryphora sassafras, Schizomeria ovata, Acmena smithii, Traustina laurina and Argyrodendron spp. The canopy reaches a height of 20 30 m. Palms are often present, as are various climbing plants, epiphytes and ferns. In the northern reaches we find an alliance dominated by Argyrodendron spp. The forests have three tree layers and in this respect resemble the richest rainforest in the tropics. They are also characterized by the presence of the climbing palm, Calamus muelleri. Floristically this type is very rich. Argyrodendron actinophyllum and A. trifoliolatum are consistently in the stands and other tree species represented abundantly in this alliance belong to the Lauraceae, Simaroubaceae, Rutaceae, Meliaceae and succelent-fruited Myrtaceae, especially Syzygium. In areas with lower rainfall, a drier type of rainforest appears, characterized by Drypetes australasica, Araucaria spp., Brachychiton discolor and Flindersia spp.
To the south of the Queensland border medium to tall open Eucalypt forests again dominate the landscape, with dozens of distinct floristic communities. The main medium open forest types include E. pilularis, E. saligna and E. maculata, while the tall forests are dominated by E acmenoides and E. microcorys.
New Zealand
Conifer-broadleaf forest represents subtropical or warm-temperate evergreen forests of North Island. In its typical development in mild lowland areas, this forest is multi-storeyed. Conifers, where present form the tallest storey, usually as well-spaced, large-crowned trees, but they can also form continuous canopies. Most of the tree species are podocarps of the genera Podocarpus, Dacrycarpus, Dacrydium and Phyllocladus, the tallest species reaching heights of over 40 m, or exceptionally 60 m. There are also two species of Libocedrus (Cupressaceae) and, north of 38oS, the massive kauri (Agathis australis). Hardwoods and some of the less-tall podocarps form the next storey at 15 to 25 m, which is usually the main canopy. Species include Beilschmiedia, Knightia, Laurelia, Litsea and Nestegis. A host of small trees form a subcanopy and fill gaps. Tree ferns and the palm Rhopalostylis sapida area usually abundant and contribute much to the subtropical appearance of vegetation. Shrubs belong mainly to the genus Coprosma and large ferns, such as Asplenium, Blechnum, Hypolepsis and others, constitute a usually well-developed ground layer. Lianas are abundant and in some forest form much of the canopy. In higher, colder or drier regions, the mixed forest becomes less rich floristically and is not so structurally complex. Small patches of beech forest (Nothofagus spp.) occur on poor soils and at higher altitudes.
In contrast with the flora of Australia, there is not a single native species of Eucalyptus or Acacia in New Zealand.
8.2.2 Subtropical dry forest (SCs)
This climatically very distinct Ecological Zone is found in two locations of Southern Australia; the southwestern tip around Perth and the central east around Adelaide.
Climate
The climate of this Ecological Zone occurs in two slightly different Mediterranean forms and has a significant rainfall gradient that has a major impact on the type of vegetation that occurs.
The area approximately 200 km south and east to 500 km north of Perth in Western Australia has hot, dry summers. Mean annual precipitation within this zone is around 750 mm, with up to 1000 mm falling on the Yilgarn Craton plateau, tapering off to around 500 mm as you move inland. Precipitation is highly winter dominant with 65 percent falling between May and August. The annual average temperature for the region is around 16oC. Average summer maximum temperatures range from 27oC in south to 30oC in the north and winter maximums average between 15o and 18oC from south to north. The average minimum temperatures in winter and summer range from 6o to 8oC and 12o to 16oC respectively. Again with a gradient from south to north.
The southern tip of Western Australia and areas to the south of Adelaide in South Australia have slightly cooler summers and are subject to a significant rainfall gradient. The region receives 400 to 800 mm of annual precipitation in Victoria and South Australia and between 1000 mm and 1300 mm on the southern coast of Western Australia, with approximately 60 percent falling between May and September. The annual average temperature of the region is 15oC. Average summer maximum temperatures range from 26o to 27oC and winter maximums average between 14o and 16oC. The average minimum temperatures in winter and summer range from 4o – 8oC and 11o to 13oC respectively. The south coast of Western Australia is generally around 2 degrees warmer than the rest of the Ecological Zone.
Physiography
The hot summer areas are largely confined to two regions. The Swan Coastal Plain, as its name suggests is a coastal lowland with marine sand dunes. In the east the plain rises sharply about 300 m to the Jarrah Forest region which is dominated by duricrusted Mesozoic sediments that form lateritic gravels interspersed with clayey soils.
Three regions make up the cooler summer zone. The Warren region on the southern tip of Western Australia which is largely undulating coastal hills dissected with deep loams and leached sandy soils. The Naracoorte Coastal Plain at the southern border of Victoria and South Australia is dominated by Tertiary and Quaternary sediments with a regular series of dunes and swales and the Lofty Block, which is a narrow strip of uplands derived from uplifted Cambrian and Late Proterozoic marine sediments which form gravelly yellow duplex soils wetter areas and red duplex soils in drier areas.
Vegetation
The vegetation in the southwest is floristically distinct from the rest of Australia. In the southern cooler climate that receives significantly more rainfall, the vegetation is dominated by tall eucalypt forest. On the more fertile soils derived from granite two tall forests occur; karri (Eucalyptus diversicolor) and red tingle (E. jacksonii). On laterite and lateritic strew jarrah (E. marginata) and marri (E. calophylla) are dominant and on the coastal limestones, tuart (E. gomphocephala). With diminishing mean annual rainfall these taller forests are replaced by other forests or woodlands. Karri is one of the tallest eucalypts in Australia, which can reach a height of circa 85 m and a diameter of c. 7 m. The species is restricted to a narrow belt in the south, where annual rainfall is more than 1000 mm. The forests are two-layered; a towering tree layer 40-70 m high with a more or less closed canopy and a tall shrub layer 3 7 m high. The herbaceous layer is poorly developed. Lianas are few, small and thin-stemmed and epiphytes are absent The Eucalyptus marginata E. calophylla association is most widely distributed in this zone, between the 600 and 1300 mm isohyets. The vegetation ranges from tall forests to shrublands, but all are characterized by one of the two, or both species being dominant. Forests up to 40 m high, with an almost closed canopy, occur in the wetter areas. In drier areas the forests reach a height of 12 24 m and are more open. Three types of understorey occur: a) in the wettest areas of tall forest, a lower tree layer up to 13 m high and below this a shrub layer of 2-3 m high; b) xeromorphic shrubs dominate in most of the upland areas; c) in the drier segment of the association, xeromorphic shrubs form an open layer. Woodlands of the same association, reaching 10 15 m height, are found mainly on the western coast on stabilized dune sands. They are now mostly cleared for cropping and grazing. In drier areas, in ecotones with the mallee dominated shrubland, both E. marginata and E. calophylla become stunted and reach heights of only a few meters.
As with many agricultural regions, the original vegetation covering the Lofty Block and Naracoorte Coastal Plain was significantly different from the cropping lands, improved pastures and low open Eucalypt woodlands with grassy understoreys that occur there today. The region was originally dominated by low to medium Eucalypt woodlands in the lower rainfall areas with gum and peppermint species such as Eucalyptus leucoxylon and E. odoratais and shrubby understoreys. Medium open stringybark forests comprising Eucalyptus baxteri, E. obliqua and E. viminalis and shrubby understoreys dominated the higher rainfall areas. Vegetation of the Naracoorte Coastal Plain was similar in many areas to that of the Lofty Block with the addition of heaths in the poorly drained lowlands and inter-dune swales and Eucalypt mallee formations (see next Ecological Zone) on the calcareous soils in the north of the region.
8.2.3 Subtropical steppe (SBSh)
The Ecological Zone is confined to Australia and separated in two distinct units following the Australian ecozoning: a northeastern part with typical subtropical characteristics and a southern part with warm temperate influences.
Climate
a) Northeastern part
This subzone comprises a significant climatic gradient that has a major impact on vegetation and landuse types that occur.
Southwestern Queensland and northwestern New South Wales have a sub-tropical semi-arid climate with mild winters and hot summers. The mean annual precipitation of 350 mm is fairly evenly distributed throughout the year, with a slight dominance from December to February. The mean annual temperature of the region is around 2oC. Average summer maximum temperature is 35oC and winter maximum is approximately 22oC. The average minimum temperature in winter is 5oC and average minimum summer temperature is 20oC. The region is commonly known as the Mulga Lands.
Southern central Queensland and northern central NSW have a sub-tropical semi-arid climate with mild winters and hot summers. The ecozone has a mean annual precipitation of 560 mm with inland precipitation decreasing to 350 mm towards the interior and increasing to 700 mm on the western slopes of the Great Dividing Range. Precipitation is evenly distributed throughout the year, with a slight dominance from December to February. The mean annual temperature of the region is around 19oC. Average summer maximum temperature is 32oC and winter maximum is approximately 20oC. The average minimum temperature in winter is 4oC and average minimum summer temperature is 18oC. This zone covers regions commonly known as the Southern Brigalow Belt, the Darling Riverine Plain, the South Western Slopes of NSW and the Cobar Peneplain.
b) Southern part
This unit has a semi-arid climate with a marked winter dominance in precipitation. It has an average annual precipitation of 375 mm with as little as 250 mm in inland areas and up to 600 mm in areas of higher altitude (300 m) towards the coast. Precipitation is markedly winter dominant with around 70 percent of the precipitation occurring between May and October. The winter dominance of precipitation increases from the east to the west. The mean annual temperature of the region is around 17oC. The average maximum summer temperature 30oC and average winter maximum is around 17oC. The average minimum temperature in winter is 5oC and average minimum summer temperature is 14oC.
Physiography
a) Northeastern part
The Mulga Lands are comprised of low hills and undulating plains on Cainozoic sediments, red earths and lithosols. The Southern Brigalow Belt is predominantly Jurassic with younger deposits of the Great Artesian Basin and Tertiary deposits with elevated basalt flows. The Darling River Plain is a series of alluvial fans and plans dominated by heavy grey clays. The South Western Slopes are an extensive area of foothills and isolated ranges on the inland sloped of the Great Dividing Range and the Cobar Peneplain is comprised of low hills and plains of Palaeozoic rocks, earths and lithosols.
b) Southern part
This subzone has a distinct climate and 4 very distinct landscapes that set it apart from other regions and create highly diverse flora:
The Murray-Darling Depression and Riverina regions of the southeast are the core of Australia food bowl with extensive gently undulating Tertiary and Quaternary sand and clay plains frequently overlain by aeolian dunes.
The Eyre and York Block region to the west of Adelaide in South Australia is comprised of Proterozoic sandstones overlain by undulating to hilly calcarenite and calcete plains which create duplex soils and calcareous earths.
The Avon Wheatbelt and Mallee regions of Western Australia are gently undulating which dissect a Tertiary plateau with a range of sandy/clay duplex soils, calcareous earths and sandplains overlying Eocene limestone in the east.
The Esperence Plains to the north of the Avon region is a sandplain overlaying Eocene sediments with abrupt granite and quartzite ranges and to the south the Geraldton Sandplains comprise of gently undulating sandy earths mantling Permian strata.
Vegetation
a) Northeastern part
The Mulga Lands are dominated by low Acacia aneura woodlands and shrublands commonly known as Mulga. This species occurs as small trees in the higher rainfall eastern margins and as a low shrub towards the interior. The original low shrubby understoreys have now been heavily modified as a result of pastoral use.
Five primary vegetation types occur within the Southern Brigalow Belt. These are: Ironbark woodlands on the eastern margins (Eucalyptus crebra, E. alba); Ironbark and Callitris forests (E. crebra, E. fibrosa and Callitris glauca) and Brigalow forests and woodlands (Acacia harpophylla) and poplar box woodlands (E. populnea) in the central and interior regions. All of which also occur as mixed forest and mosaics of relatively pure stands. Callitris glauca is a very important commercial species that can form very pure stands over extensive areas.
The Darling Riverine Plains are dominated by River Redgum (E. camaldulensis) and Blackbox (E. largiflorens). The Cobar Peneplain is dominated by Mulga (Acacia aneura) shrublands. Other species include Myall (A. pendula), Nelia (A. loderi) and Gidgee (A. cambagei). The South Western Slopes are dominated by box woodlands: Eucalyptus albens, E. melliodora, E. Blakelyi on the slopes and greybox (E. microcarpa) and ironbark (E. sideroxylon) woodlands in the lower rainfall regions.
All the above vegetation communities have considerable economic importance. They all provide grazing for domestic stock. Large tracts of woodlands have been cleared for the cultivation of grain crops, in particular wheat.
b) Southern part
Mallee is the dominant natural vegetation over large areas of the Murray-Darling, Riverina, Eyre and York Block and Mallee region of Western Australia. The term mallee, an aboriginal word, describes a eucalypt with many stems arising at ground level from a large, bulbous woody structure called a lignotuber or mallee root. In more arid areas mallee is usually replaced by acacias and at the upper rainfall limit (circa 400 mm/year) by single-stemmed eucalypts, often of the same species. The tallest of the communities, reach up to 15 m high, however, they usually are 3 to 10 m tall, with multiple, flat-topped or domed crowns spaced at regular intervals. Crown density varies from dense, interlocking in wetter areas to open in drier areas. The understorey can be either a lower shrub layer, a dense low thicket or a grass layer. About 100 species of Eucalyptus constitute the dominants and floristic composition varies by region and site conditions. There are over 100 mallee species and many species that occur as both mallee and tree lifeforms. Common species include white mallee (Eucalyptus diversifolia) which dominates the wetter communities in South Australia; Lerp mallee (E. incrassata) and narrow-leaved red mallee (E. foecunda) occurring on deep sands; Giant Mallee (E. socialis), Congoo Mallee (E. dumosa), Yorell (E. gracilis) and Redwood (E. oleosa) characterizing the main mallee alliance in the east; Tall Sand Mallee (E. eremophila) confined to Western Australia and found over a wide range of soil types. Mallee lifeforms have in the past generally been classified as shrubs. Given the overall biomass (above and below ground of theses lifeforms which is far greater than typical acacia shrublands, in 1997 Australia decided to include mallee as a specific type of forest and woodland for national and international reporting purposes.
The Esperence and Geraldton Plains are dominated by Proteaceous heaths and mallee heaths which also at various locations near the coasts of Western and South Australia. They occupy deep sands of low fertility or soils developed on fossil laterite and to a lesser extent limestones. The communities in Western Australia are extremely diverse; the total flora contains circa 2000 species and includes many endemics. Scrub-heaths can reach a height of several meters, while the heaths vary in height from 0,5 to 1,5 m. The heaths on sand are characterized by a wealth of Protaceae, including many Banksia species.
The Wheatbelt region of Western Australia has been highly modified for broad-acre wheat cropping and today only remnants of the original vegetation exist. Medium height eucalypt woodlands of 10-30 m high with low understoreys were dominant with, E. marginata (jarrah) forests in the higher rainfall areas to the west which gives way to E. wandoo (wandoo) and then E. salmonophloia (salmon gum) as rainfall decreases.
8.2.4 Subtropical desert (SBWh)
Deserts occupy a large proportion of Australia, reaching the ocean in the north, south and west. This zone can be separated into the Arid shrublands and the Arid grasslands, which bear similar climates but very different vegetation.
Climate
The climate of Australias interior shrublands is arid. With no mountains on the west coast the eastward movement of high-pressure systems from the Indian Ocean is not impeded and as a consequence, arid conditions extend from the coast to the interior. The ecoEcological Zone receives on average less than 250 mm of annual precipitation with a range of between 180 and 350 mm. Fifty percent of this precipitation occurs between December and March. The annual average temperature of the region is 22oC. Average summer maximum temperature is 35oC and average winter maximum is around 23oC. The average minimum temperature in winter is 7oC and in summer the average minimum temperature is 21oC.
The arid grasslands are concentrated within Australias largest inland drainage basin leading to Lake Eyre. The region is affected by the same air currents as above, receiving an average annual precipitation of 310 mm. However, monsoonal flooding of several inland river systems has had a major impact on the Physiography of the region which in turn changes the vegetation types that occur. As with all other regions, a precipitation gradient exists, with interior areas receiving 150-200 mm and northern areas receiving up to 400 mm annual precipitation, around fifty percent of which falls between January and March. The annual average temperature across the region is 24oC. Average summer maximum temperature is 36oC and average winter maximum is around 26oC. The average minimum temperature in winter is 8oC and in summer the average minimum temperature is 23oC.
Physiography
The physiography of the arid shrublands is incredibly diverse. This ecozone includes: the Great Sandy Desert in the north west; the Tanami Desert in the North; the Gibson and Simpson Deserts in the centre from west to east, the Great Victoria Desert and the Nullabor Plain in the south and the Murchison and Gasgoyne regions in the west, in addition to many other smaller regions with distinct physiography.
The Great Sandy Desert is comprised of Quaternary longitudinal dune fields and gently undulating Jurassic and Cretaceous sandstones. The Tanami Desert is mainly red Quaternary sandplains overlaying Permian and Proterozoic strata which are exposed locally as hills and ranges. The Gibson Desert is comprised of laterised uplands on flat lying Jurassic and Cretaceous sandstones. The Simpson desert is mainly dunefields and sandplains. The Great Victoria Desert is an active sand ridge desert of deep aeolian Quaternary sands. The Nullabor Plain is comprised of Tertiary limestones. The Murchison is mainly Quaternary alluvial and alluvial surfaces and sandplains surrounding rugged Proteozoic and sedimentary and granite ranges and the Gasgoyne is mainly rugged low Proterozoic sedimentary and granite ranges divided by broad flat valleys.
The arid grasslands are situated in the north east of the Ecological Zone and comprised of two major regions: the Mitchell Grass Downs and Channel Country. The Mitchell Grass Downs are mainly undulating downs on shales and limestones with heavy grey and brown cracking clays. The Channel Country is comprised of mitchell grass downs, braided river systems and low hills on Cretaceous sediments.
Vegetation
The enormous local and regional variation in vegetation types across the arid shrubland zone is determined by mean annual rainfall, its seasonal incidence and by soil type. In the wetter parts, annual rainfall > 250 mm, Acacia woodlands predominate and mulga (Acacia aneura) is the dominant species over vast tracts of country. The various mulga dominated woodlands show some variation in structure. Mulga itself varies in height from c. 3 10 m. The tallest stands are almost closed woodlands with scattered or no shrubs below and a discontinuous grass layer. The woodlands become progressively shorter with diminishing rainfall and in the drier areas they grade into sparse shrublands which, in the driest areas are replaced by hummock grasslands of Triodia, Plectrachne and Zygochloa. Other common Acacia species include A .translucens, A. pachycarpa and A. sowdenii. Casuarina is likewise well represented, occurring both on clays and sands, often in association with a species of Acacia. Eucalyptus is represented by many species, some of which occur in upland, sandy areas also often in combination with Acacia species, whereas other species are restricted to watercourses. In the southern regions on calcareous soils with greater than 250 mm rainfall, many Eucalypts occur in mallee formations (see detailed description above). On soils of finer texture, grasslands or halophytic shrublands occur. Grasslands of the summer rainfall zone are dominated by species of Dichanthium or Astrebla and other less abundant and in the winter rainfall zone by Stipa spp. The halophytic shrublands occupy saline and subsaline soils mainly in drier regions in the south. Other halophytic communities are present on playas.
On the grey and brown clays of the Mitchell Grass Downs and Channel Country, Astrebla spp create almost endless plains of tussock grasses. In recent years the density of these grasslands have been diminished through grazing and the invasion of exotic prickly acacia (Acacia Nilotica) which forms open tree savanna in the northeast of the former treeless plains. The braided river systems are lined with Eucalyptus coolibah woodlands and the low adjacent low hills are often dominated by Chenopodium spp. shrublands.
8.3 TEMPERATE DOMAIN
8.3.1 Temperate oceanic forest (TeDo)
This Ecological Zone covers the southeastern coast of Australia, Tasmania and lowlands of South Island, New Zealand.
Climate
Australia
The southeastern coast of mainland Australia and Tasmania has a humid, mild winter climate. With significant variations in relief and exposure, annual precipitation varies from around 600 mm in the low elevation areas of the Gippsland region in Victoria to in excess of 2000 mm in western Tasmania. Precipitation is distributed throughout the year with a slight winter dominance which is more pronounced in western Tasmania. The annual average temperature for the region varies from around 9oC in western Tasmania to 13oC in southern Victoria and eastern Tasmania. Average summer maximum temperatures range from 20oC in Tasmania to 24oC in Victoria and average winter maximums follow the same pattern with 14oC in Victoria and 10oC in Tasmania. The average minimum winter and summer temperatures for Victoria and Tasmania respectively are 4o, 11o, 2o and 8oC.
New Zealand
The western, coastal part of South Island has a humid climate with heavy rainfall. Annual rainfall ranges from around 1800 mm to locally more than 4000 mm and is rather evenly distributed throughout the year. To the east of the Alps, the climate is distinctly drier, with annual rainfall in the range of 400 to 800 mm, locally below 400 mm. Also, temperatures become more extreme here, as the region is sheltered from the prevailing western ocean winds. Mean annual temperature range from 13oC in the north to 9o in the south. Mean winter temperatures (July) range from 8oC in the north to 2o-5oC in the south, summer temperatures average 15o to 17o C.
Physiography
Australia
On the mainland of Australia the east of this Ecological Zone is a series of deeply dissected near coastal ranges composed of Devonian granites and Palaeozoic sediments, inland of a series of gently undulating terraces (piedmont downs) composed of Tertiary sediments and flanked by Quaternary coastal plains, dunefields and inlets. Its western margins comprise of extensive basaltic plains with numerous volcanic cones and eruption points and the coastal areas are again dominated by Tertiary and Quaternary sediments on lowlands, low hills and low ranges.
Soils on the lowlands hills and ranges of western Tasmania are predominantly oligotrophic acid peats. To the north, lowland hills are mainly complexes of Cambrian and Pre-Cambrian metasediments and basic volcanics with deep loams while the coastal plains are mainly acid sandy soils from post-Carboniferous sediments. The eastern margins of this Ecological Zone in Tasmania are Permo-Triassic coastal plains low Jurassic mountain ranges dominated by deep granite soils.
New Zealand
South Island is dominated by the Southern Alps, forming a central range. To the west is a narrow coastal plain, mostly consisting of gavel deposited by the numerous glacial or snow rivers. The east and southeast of the island is flat to undulating country, with the Canterbury Plain and Southland Plains as most extensive lowlands. Yellow-brown earths cover most of the eastern part of the island, while in the west and south, the predominant soils are podzolic yellow-brown earths, podzols and gley podzols.
Vegetation
Australia
The natural vegetation of this Ecological Zone consists of a complex of formations. In the wetter parts of western Tasmania cool temperate rainforests are found within a complex mosaic of rainforest and buttongrass moorlands in higher elevation areas. These forests are often dominated by myrtle (Nothofagus cunninghammii), with conifers such as huon pine (Lagorostrobos franklinii), celery top pine (Phyllocladus aspleniifolius) and King Billy pine (Athrotaxis selaginoides) also forming part of the tree layer in Tasmania. In lowland areas, mainly in the wetter south in lowland or subalpine situations, the rainforests are dominated by Anadopetalum biglandulosum. These formations are relatively poor floristically and reach heights of 10 to 20 m. In Victoria the cool temperate rainforests occur in restricted areas in the coastal ranges. Dominant canopy species include southern sassafras (Atherosperma moschatum), Acacia melanoxylon and mountain quandong (Elaeocarpus holopetalus). The tallest stands reach a height of 40 50 m and are rich in ferns.
The moderate rainfall areas to the east of this zone on the mainland and Tasmania are dominated by 20 to 30 m high dry ash, stringybark and peppermint forests (Eucalyptus sieberi, E. gummifera, E. botryoides, E. radiata, E. dives) on the granites and sediments nearer the coast. These forests are replaced by tall wet forests dominated by Eucalyptus viminalis, E. fastigata, E. obliqua and E. cypellocarpa in higher rainfall and protected areas. Many of the wetter areas of this zone in Tasmania are dominated by tall messmate/stringybark forest (Eucalyptus obliqua, E. nitida). The basalt plains of western Victoria were once dominated by wet E. obliqua and E. cypellocarpa forest but most of these have since been cleared.
Other vegetation types of this Ecological Zone include wet and dry sclerophyllous woodlands, heaths (mostly along the coast) and grasslands often dominated by species of Stipa.
New Zealand
The distinct climatic west-east division is also reflected in the native vegetation. The western lowlands and lower hills are dominated by beech and conifer-beech-broadleaf forest. The latter forest type predominates in the northwest and central west and has similarities with the forests of the North Island described earlier. There is however variation in dominating species. Nothofagus fusca is characteristic for conifer-beech-broadleaf forests in the northwest. In these forests, conifers form a scattered overstorey with Dacridium cupressium and Podocarpus ferrugineus as the main species. Beeches form the main canopy, with N. fusca predominating on the deeper, more freely drained sites, but is usually mixed with N. truncata, N. menziesii and, on gradients towards gley podzols, with N. solandri. On the optimal sites, Weinmannia racemosa and in places Quintinia acutifolia form a tall subcanopy. Weinmannia racemosa is favoured by high rainfall and on lower hill slopes in Westland it is the main tall tree in a luxuriant aspect of conifer-broadleaf forest. In the extremely humid fjord country in the southwest, where rainfall exceeds 6000 mm, the Nothofagus forests are similar in nature to those of Southern Chile. N. menziesii is the dominant species in these southern beech forests.
The east of South Island has little forest vegetation, due to the much lower rainfall. Patches of beech conifer-broadleaf forest occur, adjoining a wide variety of, mostly anthropogenic, vegetation: Pteridium fernland, Leprospermum shrubland, tussock grassland, succesional forest, alien communities such as those dominated by Rubus fruticosus and Ulex europaeus. There is evidence that prior to human intervention a zone of microphyllous woodland, consisting of species such as Coprosma virescens, Discaria toumatou, Leptospermum ericoides, Olearia lineata and Sophora microphylla, grew under moisture regimes intermediate between those supporting forest and semi-arid grasslands.
8.3.2 Temperate mountain systems (TeM)
In Australia, this Ecological Zone consists of the Tasmanian Highlands, the Southeastern Highlands, Australian Alps and the New England Tablelands. New Zealands Southern Alps on South Island are also part of the Ecological Zone.
Climate
The highlands and tablelands of southeastern Australia have a cool temperate climate. With an average elevation of around 750 m and many areas exceeding 1500 m, it has extremes of both precipitation and temperature. Annual precipitation throughout the region ranges from around 600 mm in lower elevation areas to 1200 mm in areas of higher elevation, with an overall average of 950 mm. Localised rainshadow areas are also common which receive less than 500 mm annually. The precipitation is evenly distributed throughout the year, with most months receiving 70-80 mm. The annual mean temperature is around 12oC with mainland areas around 2o hotter and Tasmania 4o colder. Average summer maximum temperatures range from 20oC in Tasmania to 25oC on the mainland and average winter maximums follow the same pattern with 12oC on the mainland and 6o – 8oC in Tasmania. The average minimum winter temperature of 0.5o to 1.0oC does not vary significantly across the region, whereas the average minimum summer temperatures range from 12oC in the northern tablelands, 10oC in the southern tablelands and 7oC in Tasmania.
The Australian Alps region of southeastern Australia receives an average annual precipitation of 1300 mm, with higher elevation areas receiving in excess of 2000 mm, much of which falls as snow. Precipitation is evenly distributed throughout the year, with a slight winter/spring dominance. The annual average temperature for the region is around 9oC. The average summer maximum temperature ranges from 16o to 22oC and winter maximum temperatures range from 2o to 6oC. The average minimum temperatures in winter and summer range from 0o to 4oC degrees and 6o to 8oC respectively. Variation in elevation is obviously the major driver of temperature variation.
Climate of the Southern Alps in New Zealand is cold temperate, characterized by high annual rainfall particularly on the western slopes. Frost and snow are abundant in winter and to some extent at all seasons.
Physiography
Australia
The Southeast Highlands comprise of rolling hills at lower elevations (600-800 m) in the north through to highly dissected mountain ranges. The geology is predominantly Palaeozoic and Mesozoic formations with small Tertiary basalt flows. The New England Tablelands is an elevated plateau of rolling hills on Palaeozoic sediments, granites and basalts. The Central Highlands and midlands of Tasmania is also an elevated plateau underlain by Jurassic dolarites and Tertiary basalts. The Australian Alps is a series of high elevated plateaux capping the South East Highlands. The geology consists largely of basalt and granite. The highest altitude is found in the Australian Alps where several mountain tops and plateaux exceed 2000 m in height.
New Zealand
The Southern Alps constitute a prominent feature of New Zealands Southern Island. The highest peaks, situated at the centre of the range, reach from 3000 to 3764 m (Mt. Cook). Proceeding north and south the range gradually decreases in height, but few peaks are lower than 1800 m. The eastern slopes are formed of slaty shales and greywackes. Below the shales on the west, the rock is schist, but at low levels occasionally gneiss. The snowline in the Southern Alps is on average at about 2200 m, varying according to latitude, while it is lower on the west than on the east. The central part of the range is heavily glaciated, the size of the glaciers being correlated with the altitude of the peaks.
Vegetation
Australia
The lower elevation rolling hills of the Southeast Highlands and elevated plateaux and hills of the New England Tablelands were originally covered with Eucalypt forests and woodlands dominated by stringy bark/peppermint/box species, including E. caliginosa, E. laevopinea, E. nova-anglica. E. melliodora, E. albens and E. blakelyi. Today these communities mainly occur as open woodlands used for sheep and cattle grazing.
In areas sheltered areas receiving greater than 1000 mm annual rainfall, tall wet Eucalypt forests dominate with species such as alpine ash (Eucalyptus delegatensis), mountain white gum (E. dalrympleana), manna gum (E. viminalis) forming open forests where the canopy exceeds 40 m with understoreys of shrubs and ferns. The most brilliant example of theses forests occur in the southern ranges of Southern Victoria and Tasmania where mountain ash (E. regnans) trees commonly exceed 70 m in height and can reach over 90 m on the best sites. In Tasmania, cool temperate rainforests are dominated by myrtle (Nothofagus cunninghamii) and blackwood (Acacia melanoxylon) often forms an understorey 10-30 m tall.
Above 1500 m elevation, low snow gum (E. pauciflora) woodlands are prominent with diverse shrub and tussock grass understoreys. These woodlands also occur at lower altitudes on sites receiving cold air drainage. The treeline reaches a maximum altitude of around 1800 m elevation (less in cold air drainage zones) on the mainland and 1400 m in Tasmania, with Australias highest point being 2228 m above sea level. Diverse mixtures of low shrubs including Podocarpus lawrencei, tussock grasses and forbs form a complex mosaic across these treeless areas.
New Zealand
The lower and medium altitude zones of the mountains are mostly covered by beech forest. Nothofagus var. cliffortioides or N. menziessi constitute most of the subalpine forests, forming remarkably level, abrupt timberlines against alpine grasslands. The timberline reaches at around 1200 m in the north and decreases to around 850 m in the south. In such subalpine beech forests, other than the dominant tree, which forms a dense canopy at 10 to 15 m, there may be only scattered Coprosma shrubs, corticolous lichens and bryophytes and bryophyte cushions (Dicranoloma, Leucobryum) on the forest floor. On moist concave slopes, however, there can be a dense understorey of the ferns Hypolepis millefolium and Polystichum vestitum. Locally, beech forest is altogether absent. Instead, depauperate conifer-broadleaved forest extends into the subalpine belt. Its conifer storey consists of Podocarpus halii, often accompanied by Libocedrus bidwillii, while the main canopy consists of Weinmannia racemosa, Metrosideros umbellate, or in certain circumstances, small trees such as Dracophyllum traverssi, Griselinia litoralis and Olearia ilicifolia. Upwards, this forest grades into very dense subalpine scrub dominated by composites (Olearia, Senecio), small podocarps (e.g. Dacrydium biforme, Phyllocladus alpinus, Podocarpus nivalis), epacrids (Archeria, Dracophyllum) and various other genera.
REFERENCES
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