Native vegetation comprises plants that are indigenous to Australia, including trees, shrubs, sedges, herbs and grasses, and incorporates lower lifeforms such as mosses, lichens and fungi. Many of our diverse types of native vegetation have adapted to cope with Australia’s highly variable climate, ancient nutrient-depleted soils and ubiquitous fire regimes (Keith 2017). The unique character of our vegetation is embedded within Australia’s cultural identity. Indeed, from Indigenous peoples’ perspective, a sense of place and belonging can be defined by Country. For instance, people of the wet tropics of northern Queensland identify as Rainforest People.
Native vegetation is crucial for the health of Australia’s environment – it stabilises soil, supports pollinators and other animals, purifies water, stores carbon, and provides food and habitat for biodiversity. Many of Australia’s tree species depend on soil microbes for their survival – for example, through close associations with specialised fungi known as mycorrhizae (see Soil). Vegetation and fungi together provide a foundation of the food chain for land-based ecosystems and biodiversity. All these services also support our economy.
The economic value of native vegetation is immense, but not yet fully quantified in Australia. In many parts of Australia, native vegetation has been cleared or degraded and fragmented by human activity to enable other uses of the land (see Pressures). As a result, many of Australia’s unique plants and animals have become endangered (see the Biodiversity chapter). However, in recent years, Australia has invested significantly in the sustainable use and conservation of native vegetation, including efforts to manage and protect natural areas (see Protected areas), and begin to restore degraded landscapes to functioning systems (see Retaining and restoring natural capital assets). Despite these policy responses, Australia’s native vegetation continues to decline in extent and condition, suggesting the investment may not always be directed to the areas that need it most (Evans 2016, Reside et al. 2017, Ward et al. 2019).
Vegetation extent
Overall, 13.2% of Australia’s native vegetation, as mapped by state and territory agencies across Australia, has been replaced by urban, production and extractive uses of the land (Figure 2) (DAWE 2020g) (see Land use). Regrowth and other modified native vegetation make up a further 0.3% of the land area. The native vegetation that remains makes up 86.5% of the continental land area. Hummock Grasslands, Acacia Shrublands and Eucalyptus Woodlands together make up 47% of the current extent of native vegetation across Australia. Vegetation groups vary in the diversity of native species they support (see the Biodiversity chapter).
Eleven major vegetation groups have lost at least 20% of their original extent (Figure 3). Eucalypt Woodlands have been extensively cleared, with 67% of the pre-1750 extent remaining (see Land clearing). Other major vegetation groups have even less of their original extent remaining. For example, Casuarina Forests and Woodlands, which make up 0.4% of all native vegetation that remains (Figure 2), have only around half of their original extent (53%) remaining (Figure 3).
Overall, the amount of ‘remnant’ native vegetation mapped in datasets published in 2020 has reduced by around 1.36 million hectares (ha) compared with the 2012 dataset (Table 1). This is largely a net result of an additional 1.26 million ha mapped as ‘removed’ and 0.24 million ha mapped as ‘regrowth/modified’ in areas previously identified as ‘remnant’ native vegetation. There is an additional 0.99 million ha of ‘removed’ native vegetation and 1.15 million ha of ‘regrowth/modified’ vegetation compared with datasets published in 2012; 0.30 million ha previously classed as ‘removed’ is now classed as ‘regrowth/modified’.
National Greenhouse Accounts data roughly accord with the story of clearing and regrowth seen in the national vegetation data: overall across Australia and over time, primary vegetation is cleared, some regrows and some regrowth is recleared, but generally and cumulatively the extent of removed native vegetation increases (see Land clearing).
Native vegetation that has been removed or partially regrown has reduced ecological integrity. However, the extent of ‘remnant’ and ‘regrowth/modified’ native vegetation (Figure 2; Table 1) is not assessed based on its condition. Additional information is needed to assess the growth stage and ecological integrity of ‘remnant’ and ‘regrowth/modified’ vegetation for a more comprehensive understanding of the implications for biodiversity and land condition (see Vegetation condition).
In 2016, Australia had 134 million ha of forest covering 17% of the total land area, including nearly 2 million ha of plantation and other non-native forest types, making up 3% of the world’s forests (Table 1.2 in MPIGA & NFISC 2018). Most forests occur along the northern, eastern, south-eastern and south-western coasts of Australia, generally where average rainfall exceeds 500 millimetres per year; however, they can also be found in drier parts of the country. The National Greenhouse Accounts additionally identify 65 million ha of sparse woody vegetation that does not meet the strict definition of a forest used for international reporting (DISER 2021d) (see Carbon).
A comprehensive third edition of the source book on Australia’s native vegetation was published in 2017 (Keith 2017). This fully updated edition presents the latest insights on the patterns and processes that shaped the vegetation of Australia, and provides detailed ecological portraits for each major vegetation type.
Vegetation condition
The condition of native vegetation is assessed in terms of its integrity or capacity to continue providing habitat to support Australia’s unique biodiversity. This is consistent with Australia’s former Native Vegetation Framework (COAG Standing Council on Environment and Water 2012), in which condition is defined as ‘the capacity of a native vegetation community to support the full range of native species that might be expected to use a stand of vegetation of a particular type under natural circumstances’. Areas of high ecological integrity are also well placed to provide valuable ecosystem services such as pollination, water purification and nutrient cycling.
Removed or degraded habitats directly and indirectly cause long-term and cumulative declines in local and regional biodiversity due to, for example, fragmentation, edge effects and invasion by non-native species (Haddad et al. 2015, Neldner 2018, Sonter et al. 2018, Kearney et al. 2019) (see Introduced and invasive species) (see the Biodiversity chapter).
Native vegetation supports a wide range of land uses, such as grazing, honey production, wood product extraction, infrastructure networks and a wide range of recreational opportunities (see Land use). These land uses, while providing social and economic benefits, result in reduced capacity of habitats to support the biodiversity originally found there.
The cumulative impact of multiple pressures over many decades across regions and landscapes, and especially in intensive land-use zones, exacerbates fragmentation and further contributes to reductions in the quality of remnant native vegetation as habitat for Australia’s unique flora and fauna (see the Biodiversity chapter). Of the 18 ecosystems identified by Bergstrom et al. (2021) to be at risk of collapse – potentially irreversible change to ecosystem structure, function and composition – 10 are terrestrial (see the Biodiversity chapter). An understanding of the drivers and pressures associated with ecosystem collapse is needed to determine threat status using the International Union for Conservation of Nature (IUCN) Red List of Ecosystems (Keith et al. 2013, Bland et al. 2017, Bland et al. 2018). The IUCN aims to use this framework to assess the risk of collapse for all the world’s ecosystems by 2025 (Sato & Lindenmayer 2018).
As we enter a period of unprecedented environmental change, we can expect many ecosystems to undergo sudden, unpredictable and often irreversible transitions to new states, despite how well adapted the Australian biota is to climate variability (Harris et al. 2018) (see Climate change). Already, in one unprecedented event in the summer of 2019–20, bushfires burned more than 8 million hectares of native vegetation across 11 bioregions, and 17 major vegetation types were severely burned (Godfree et al. 2021). The massive scale of the impacts in general, and particularly on fire-sensitive ecosystems such as the Gondwana rainforests, may leave some ecosystems susceptible to collapse and exacerbate biodiversity decline (Ward et al. 2020, Godfree et al. 2021). To monitor and track outcomes, multiple indicators will be needed to capture the different dimensions of ecosystem type, extent, condition and risk of collapse (Nicholson et al. 2021). Approaches that integrate observations with models and future scenarios will be fundamental to ensuring those indicators are well founded (Nicholson et al. 2019) and support the broader community in planning their future (Pereira et al. 2020).
Habitat modification
Condition is quantified by measuring the similarity of a current ecosystem to a historical reference state with high ecological integrity or one that is minimally impacted by people (UNCEEA 2021). The condition of habitat for biodiversity is generally inversely related to the degree to which the land has been modified for agricultural production, resource extraction, urbanisation and related uses (see Land use). Habitats can also be degraded by altered disturbance regimes such as fires outside the normal range of intensity and fire return intervals (Gosper et al. 2019, Tran et al. 2020, Gallagher et al. 2021).
The intensity of land use by people has been used as a proxy for levels of habitat modification and thereby related to ecosystem intactness or integrity (Watson & Venter 2019). For example, the human footprint (a quantitative analysis of human influence; Scott 2020), which uses mapped information such as the built environment, population density, land use and infrastructure networks, showed that by 2009, 75% of the globe was experiencing measurable human pressures (Venter et al. 2016a, Venter et al. 2016b). Beyer et al. (2020) used the human footprint data to assess ecoregion intactness as a measure of habitat quality for biodiversity. They found that most ecoregions in eastern Australia appear to be transitioning to highly degraded states. Williams et al. (2020b) and Williams et al. (2020a) updated the map of the human footprint and reported that by 2013 58.4% of Earth’s surface was highly modified, although Australia was one of the few regions they considered relatively intact (Figure 4). In a related global analysis incorporating landscape connectivity, Grantham et al. (2020) reported that only 40% of the world’s forests remained intact. On a scale of 1 to 10 (lowest to highest integrity), Australia’s remaining native forests scored 7.22 for landscape integrity in 2019 (Grantham et al. 2020). This analysis did not account for the original extent of native forests in Australia, which would have reduced the score.
Within Australia, most states and territories have developed field protocols for benchmarking and measuring habitat condition to support regulation of native vegetation clearing and management (e.g. Parkes et al. 2003, Michaels 2006, Eyre et al. 2015). Those field protocols typically comprise 2 components of condition: a local site-level score and a landscape-level score to account for the effects of fragmentation on the site. New South Wales and Victoria have separately developed methods to map condition spatially, incorporating both local and landscape contexts (Newell et al. 2006, DSE 2007, Love et al. 2020). Queensland is also developing a mapping methodology to accompany their BioCondition field protocol (Eyre et al. 2018).
In New South Wales in 2013, only 33% of the original habitat effectiveness (based on an analysis of ecological carrying capacity) remained to support native species (DPIE 2020d) (Figure 5). Fragmentation had reduced the site-level score of habitat effectiveness by 25% (Love et al. 2020). In 2018, the New South Wales Government reported that only 15% of remnant native vegetation was in close-to-natural (i.e. benchmark) condition (NSW EPA 2019). Following the extensive bushfires of 2019–20, the New South Wales Department of Planning, Industry and Environment (DPIE 2020b) reported ecological carrying capacity in the fireground was reduced by 39% compared with 2013. That assessment reflected the immediate post-fire effects, with expected improvements in future assessments where there is regeneration and regrowth (DPIE 2020b).
National monitoring
The development of a national monitoring system to measure changes in the condition of representative native vegetation communities across Australia by 2016 was a target under Australia’s former national Native Vegetation Framework (COAG Standing Council on Environment and Water 2012:46). In the Land chapter of the 2016 state of the environment (SoE) report, Metcalfe & Bui (2017:111) reported the steps being taken by the CSIRO (Harwood et al. 2016) in developing a remote-sensing approach to consistently monitor habitat condition nationally. The Habitat Condition Assessment System (HCAS) has since evolved (Williams et al. 2020c, Williams et al. 2021b) and provides, for the first time, an independent basis for national reporting on site-level habitat condition that is not closely coupled to land-use mapping (see case study: Assessing condition of habitat consistently and nationally).
This national analysis of site-level habitat condition identifies the most intensively used regions – those associated with the major agricultural areas – for example, the ‘southern volcanic plain’ and ‘south-eastern coastal plain’ bioregions adjacent to Melbourne, the southern and agricultural parts of South Australia, and the Avon Wheatbelt in Western Australia (Figure 6) (see Agriculture).
All remaining native vegetation (Figure 2) has been ‘modified’ to some extent across its range (represented by HCAS scores below 0.8) and some to a very high degree (HCAS scores below 0.6) as of 2018 (Figure 7). In cleared areas, native vegetation has been substantially ‘replaced’ or ‘removed’ (lowest mean HCAS score of 0.2; Figure 7). The most intact vegetation groups (highest mean HCAS scores approaching 0.9; Figure 7) are those that dominate Australia’s remote arid interior, including Acacia Open Woodlands, Acacia Shrublands and Hummock Grasslands. However, even these systems are vulnerable to collapse due to invasion by transformer weeds such as buffel grass, which is altering fire regimes, compounded by heatwaves (Bergstrom et al. 2021) (see Introduced and invasive species). This assessment uses HCAS as of 2018 (Williams et al. 2021b), before landscape-level impacts of catastrophic fires in the summer of 2019–20 (Godfree et al. 2021). In future analyses, the additional effects of fragmentation will also be incorporated (see case study: Assessing condition of habitat consistently and nationally).
Figure 8 illustrates the relative degree of modification of Australia’s pre-1750 native vegetation across the continent as assessed by HCAS and equated with the Vegetation Assets, States and Transitions (VAST) narrative framework (see Figure 3 for extent). Only around 40% of the formerly extensive Eucalypt Woodlands appear relatively intact at the site level (VAST ‘residual’ class, HCAS (Metcalfe & Bui 2017), there are significant departures (e.g. lower than expected modification of Callitris Forests and Woodlands, Acacia Forests and Woodlands, Tussock Grasslands, and Acacia Open Woodlands). These departures are in part due to data currency and to a reliance of the VAST framework implementation (Lesslie et al. 2010) on pressures projected from land-use mapping that may not yet be fully realised. The differences may also be due to how the VAST framework is quantitively related to the HCAS scores. More work needs to be done to comprehensively assess and map the extent and condition of Australia’s native vegetation, its states and transitions, and potential for recovery. The framework developed by Richards et al. (2020) provides a starting point for organising data and expert knowledge for this effort.
Ongoing clearing of native vegetation and intensification of land use in remnant areas continue to degrade environmental values.
Related to United Nations Sustainable Development Goal targets 15.1, 15.2, 15.4
Many native ecosystems have been extensively cleared and at least 50% of remaining habitats are highly degraded. There are local areas of restoration and regrowth.
Some clearing of native ecosystems and more extensive grazing pressures have reduced the overall quality. Land-use intensification and conversion, as well as increasingly frequent and intense fires, contribute to degradation.
Many of the native ecosystems remain intact, but are vulnerable to potential impacts of ongoing small-scale land-use change, invasive species pressures and extreme climate events.