The Greater Blue Mountains Area is an exceptionally remarkable World Heritage Property that integrates eight major protected areas - Blue Mountains National Park (NP), Wollemi NP, Yengo NP, Garden of Stone NP, Kanangra-Boyd NP, Natti NP, Thirlmere Lakes NP and Jenolan Caves Conservation Reserve. This property is located in New South Wales, on the west coast of Sydney, Australia. Its landscape consists of sandstone tabletop plateaus whose elevation ranges from 20 m near the Nepean River at Glenbrook to over 1330 m at Mount Emperor near Jenolan Caves. The plant species that makes up most of the vegetation cover is Eucalyptus. These gum trees are a characteristic Australian group of species belonging to the Myrtaceae family. Eucalyptus deanei, Eucalyptus saligna, Eucalyptus sclerophylla and Eucalyptus cunninghamii are some of the prominent species at different elevations.
According to a recent survey, the Greater Blue Mountains Area is an abode to macroinvertebrate organisms (mainly A view over Jamison Valley, in 2008 Source: Wikipedia Boyd River campground in winter (Kanangra-Boyd National Park) Source: Wikipedia in aquatic ecosystems) and 68 mammal, 254 bird, 74 reptile and 36 frog species.
Despite being protected, the Greater Blue Mountains Area has been facing several threats. There have been issues of introduction of alien species of Lantana in many areas of the property. Usually, due to the low mean temperature, Lantana remain scarce and restricted to small areas; however, due to the climate change and habitat disturbances, the species have spread extensively, which is destroying the endemic plant species. Next, there has been much concern on water pollution by sewage effluents from urban housing and coal mine discharge. This has resulted in degradation of aquatic biodiversity, mainly that of macroinvertebrate organisms. Rise in tourism has resulted in urbanization and increase in recreational activities such as canyoning, which has caused trampling of the vegetative grass cover. Fire occurrences are also frequent within the site, and the vital endemic species have evolved accordingly.
One of the largest protected areas, the Greater Blue Mountains Area is located in New South Wales on the west coast of Sydney, Australia. It encompasses eight significant protected areas - Blue Mountains NP, Wollemi NP, Yengo NP, Garden of Stone NP, Kanangra Boyd NP, Natti NP, Thirlmere Lakes NP and Jenolan Caves Conservation Reserve (Hager and Benson 2000). The property extends approximately 200 km south from the Hunter Valley to the Southern Tablelands and 35 to 100 km west from the Nepean River to the top of the Great Dividing Range (Smith and Smith 2020).
The elevation of the Greater Blue Mountains Area ranges from 20 m near the Nepean River at Glenbrook to over 1330 m at Mount Emperor near Jenolan Caves. Yengo NP lies at the lowest plateau with extensive areas below 300 m elevation, and the rest of the Greater Blue Mountains World Heritage Area (GBMWHA) is generally higher than 400 m. With increase in the altitude, the climate becomes colder and wetter. The Upper Mountains are met by frost, fog and snow (Smith et al. 2019; Hager and Benson 2010). The climate is much warmer in the lower eastern and northern areas (Hager and Benson 2010). Annual rainfall over most of the GBMWHA is moderate (800-1200 mm p.a.), which increases with elevation to 1400 mm p.a. in the central Blue Mountains (Katoomba to Newnes Plateau) and in Kanangra-Boyd NP. However, rainfall progressively decreases north of Newnes Plateau, being lowest in the northwest in northern Wollemi (Hager and Benson 2010).
The Greater Blue Mountains Heritage Site is remarkable for its Eucalyptus-dominated landscape because of which the region represents a substantial portion of Australia's biodiversity (e.g. containing 14% of all eucalypt taxa, and substantial numbers of rare or threatened species, including evolutionary relict species such as the Wollemi pine (Wollemia nobilis) (Chapple et al. 2011; NSW NPWS 2009). The sandstone plateau forest dry sclerophyll vegetation is epitomized by Eucalyptus sieberi and Eucalyptus piperita (National Herbarium 1977). In fact, it is described as a natural laboratory to study the evolution of eucalypts (Hager and Benson 2010).The wide-ranging elevations, geologies, landforms, soils, climatic conditions as well as fire histories have moulded the development of a montage of different types of eucalypt forest and woodland, interspersed with other habitats such as rainforest, heath, swamp, open wetlands, watercourses, cliffs and other rock formations (Smith and Smith 2020).
The eucalypts or gum trees are a characteristic Australian group of species belonging to the Myrtaceae family. The site has over 98% of the 700 or so known endemic eucalypt species, and 98 eucalypt taxa (mostly species of Eucalyptus but including five Angophora and four Corymbia species) have been recorded in the eight reserves of the GBMWHA (Smith et al. 2018). Species diversity varies in size from large forest trees (30 m in height) (e.g. Eucalyptus deanei, Eucalyptus saligna), through spreading woodland trees (e.g. Eucalyptus sclerophylla) to small multi-stemmed mallees (less than 1 m in height in heathland) (e.g. Eucalyptus cunninghamii). Eucalyptus bensonii, Eucalyptus baeuerlenii, Eucalyptus hypostomatica, Eucalyptus michaeliana and Eucalyptus laophila are profusely found and protected within the GBMWHA. Eucalyptus bensonii, Eucalyptus burgessiana and Eucalyptus cunninghamii are three of the six rare mallee eucalypts endemic to the GBMWHA (Hager and Benson 2010)
Species such as Eucalyptus pauciflora and Eucalyptus laevopinea grow at higher elevations, while Eucalyptus rubida, Eucalyptus stellulata and Eucalyptus aggregata prefer lowland areas. Angophora costata and Corymbia eximia usually have a widespread distribution at lower elevations of the GBMWHA. Widespread on the NSW Western Slopes are Corymbia trachyphloia subsp. amphistomatica, Eucalyptus dawsonii and Eucalyptus beyeriana (Hager and Benson 2010).
With a rich native floral diversity of around 1500 plant species (NSW National Parks and Wildlife Service 2009), the sandstone tabletop landscape has some iconic plant species such as the Wollemi pine (Wollemia nobilis) (CE), the pink flannel flower (Actinotus forsythia) (appears after fires), the more common waratah (Telopea speciosissima) and the mountain devil (Lambertia formosa) (Hager and Benson 2010).
In terms of faunal diversity, a recent study had reported a total of 432 native terrestrial vertebrate species that have been reliably recorded within the Greater Blue Mountains World Heritage Area since European settlement. These include 68 mammal, 254 bird, 74 reptile and 36 frog species (Smith and Smith 2020). The paper mentioned that the 68 mammals include representatives of 21 families and all three evolutionary lines, monotremes, marsupials and placentals. Two of only three surviving species of monotremes - the platypus (Ornithorhynchus anatinus) and short-beaked echidna (Tachyglossus aculeatus) - significantly inhabit the World Heritage Area. There are over 29 species of marsupials that represent Australian biodiversity, such as carnivorous quolls, insectivorous antechinus and dunnarts, omnivorous bandicoots, and herbivorous gliders, possums, wombats, koalas, kangaroos and wallabies. The striated pardalote (Pardalotus striatus), Australian magpie (Gymnorhina tibicen), eastern yellow robin (Eopsaltria australis), silvereye (Zosterops lateralis) and eastern banjo frog (Limnodynastes dumerilii) are some of the most prominent species in the GBMWHA (Smith and Smith 2020).
The Greater Blue Mountains include outstanding and representative examples in a relatively small area of the evolution and adaptation of the genus Eucalyptus and eucalypt-dominated vegetation on the Australian continent. The site contains a wide and balanced representation of eucalypt habitats including wet and dry sclerophyll forests and mallee heathlands, as well as localized swamps, wetlands and grassland. It is a center of diversification for the Australian scleromorphic flora, including significant aspects of eucalypt evolution and radiation. Representative examples of the dynamic processes in its eucalypt-dominated ecosystems cover the full range of interactions between eucalypts, under-storey, fauna, environment and fire. The site includes primitive species of outstanding significance to the evolution of the earth's plant life, such as the highly restricted Wollemi pine (Wollemia nobilis) and the Blue Mountains pine (Pherosphaera fitzgeraldii). These are examples of ancient, relict species with Gondwanan affinities that have survived past climatic changes and demonstrate the highly unusual juxtaposition of Gondwanan taxa with the diverse scleromorphic flora.
The site includes an outstanding diversity of habitats and plant communities that support its globally significant species and ecosystem diversity (152 plant families, 484 genera and c. 1,500 species). A significant proportion of the Australian continent's biodiversity, especially its scleromorphic flora, occur in the area. Plant families represented by exceptionally high levels of species diversity here include Myrtaceae (150 species), Fabaceae (149 species), and Proteaeceae (77 species). Eucalypts (Eucalyptus, Angophora and Corymbia, all in the family Myrtaceae) which dominate the Australian continent are well represented by more than 90 species (13% of the global total). The genus Acacia (in the family Fabaceae) is represented by 64 species. The site includes primitive and relictual species with Gondwanan affinities (Wollemia, Pherosphaera, Lomatia, Dracophyllum, Acrophyllum, Podocarpus andAtkinsonia) and supports many plants of conservation significance including 114 endemic species and 177threatened species.
The diverse plant communities and habitats support more than 400 vertebrate taxa (of which 40 are threatened), comprising some 52 mammal, 63 reptiles, over 30 frog and about one third (265 species) of Australia's bird species. Charismatic vertebrates such as the platypus and echidna occur in the area. Although invertebrates are still poorly known, the area supports an estimated 120 butterfly and 4,000 moth species, and a rich cave invertebrate fauna (67 taxa).
According to the state of conservation reports by UNESCO of the years 2001, 2004 and 2019, the primary factors affecting the heritage property are mining and pollution of the surface water and aquatic ecosystems. Pollution in the streams and rivers of Greater Blue Mountains Area has also raised concerns in terms of conservation of the World Heritage Site. Historically, the primary source of water pollution in the Blue Mountains Area has been sewage effluent. There were 12 sewage treatment plants (STPs) in the Blue Mountains (MWS&DB 1987) in 1980. By the early 1990s, six STPs disposed of the wastewater into streams that flowed into the National Park estate lands (Berman et al. 1987). For more than a century, water pollution throughout Australia, and in the Blue Mountains Area, has been due to coal mining (Macqueen 2007). To protect the aquatic biodiversity and landscape, many of the mines were closed; however, a few still persist in the Lithgow and upper Coxs Valley area (Lithgow Tourism 2009) in the Western Blue Mountains. The Grose River catchment is located approximately in the centre of the Greater Blue Mountains Area, to the immediate north of the urban corridor that runs between Penrith and Mount Victoria. The Grose River has suffered two different forms of water pollution (Wright et al. 2010). The first is organic pollution from treated sewage effluent from the Blackheath STP (Wright and Burgin 2009), and the second is contaminated drainage from a derelict coal mine, the Canyon Coal Mine (Wright et al. 2010).In 2014, a report on degradation of aquatic ecosystems in the Blue Mountains World Heritage Area pointed fingers at the Clarence Colliery mine which discharges coal mine water into the Wollangambe River, causing pollution-related physical and chemical changes to the water quality as well as changes in macroinvertebrate communities. The waste discharge from the mining operation increased the water temperature, salinity and pH, modified the ionic composition of the river water, and elevated zinc and nickel concentrations to potentially toxic levels (Belmer et al. 2014). According to IUCN's 2020 report, there is major concern about invasive species that have caused havoc in the endemism of the site (IUCN Consultation 2020). Invasive species are introduced to a particular region due to anthropogenic interference such as vegetation clearing and associated habitat loss and climate change (Gurevitch and Padilla 2004).
Lantana (Lantana camara) was first introduced in the Australian continent in the mid-1800s as an ornamental shrub (Swarbrick 1986). But soon it invaded the endemic biodiversity on the east coast of the continent, ranging from Cairns in far-north Queensland to the south coast of New South Wales (Smith and Smith 1982; Parsons and Cuthbertson 2001).
Lantana camara currently has a limited distribution within the boundaries of the GBMWHA; however, it has the potential to expand its range within the area and threaten its prevalent biodiversity (Gold et al. 2011). Studies have reported that warmer climates allow better expansion of Lantana within Australia (Gold et al. 2011) and bring permanent loss of native species with restricted ranges. Currently, the weed is restricted to only the warmer reaches of the area, and it's anticipated that there is a chance of surge in Lantana expansion from 8% at present to 41% after 10C of warming and to 94% after 20C of warming (Gold et al. 2011). In the case of fauna, the known invasive species are foxes, cats, carp, deer, dogs, goats, horses, pigs, rabbits and cattle, mainly predators like foxes and cats (Pascoe 2011; Pascoe et al. 2011). Tourism clearly increased as the Greater Blue Mountains Area was acknowledged for its stunning landscape. The latest tourism trend in the GBMWHA is the inclusion of adventure recreation activities (Buckley 2005), which has had several negative impacts on the vegetation and biodiversity of the area, particularly the impact on in-stream fauna due to trampling and canyoning by visitors (Hardiman and Burgin 2010). Previous research (Povey and Keough 1991; Keough and Quinn 1998; Ross 2006) has demonstrated that trampling can have a detrimental impact on benthic macroinvertebrate communities of coastal intertidal ecosystems that may take multiple years to disintegrate (Ross 2006). Trampling in the narrow slot valley canyons of the Greater Blue Mountains World Heritage Area had an immediate detrimental effect (1-day recovery) on the community composition of resident macroinvertebrates at 50 tramples/day.
There was a reduction in taxa in the trampled areas compared to untrampled ones (Hardiman and Burgin 2010). With rising urbanization, fauna mortality on urban/peri-urban roads is at risk and the factors include distance from vegetative cover, type of road (Clevenger et al. 2003), presence/absence of barriers and seasonal activity patterns (Burgin and Brainwood 2008; Clevenger et al. 2003). Roadways offer open, warm basking areas compared to the surrounding environment, making reptiles vulnerable to road kills (Tunner and Perry 2007). Studies claim that several species may become locally extinct as a result of new road development (Lunney et al. 2002). In the buffer zone of the GBMWHA, there are 26 towns and road kills have been prevalent for the last 20 years. Jacky dragons were the most commonly encountered road killed reptile. Others included frogs, snakes, lizards and geckos (Wotherspoon and Burgin 2011). The Greater Blue Mountains Area is within one of the most bushfire prone areas of Australia (Hammill and Tasker 2010). Aboriginal burning practices, European fire management and recurring wildfires (millions of years ago) have been important factors in the evolution of the local fauna. The differing combinations of fire frequency, intensity, season and extent have contributed to the diversity of fauna habitats.
Although the site is well managed and monitored by the management committee by practicing the Greater Blue Mountains World Heritage Area Strategic Plan (National Parks and Wildlife Service, New South Wales 2009), the protected area still faces a lot of pressure externally, and so IUCN has declared the site good with some concerns' in the IUCN 2020 assessment.