Terrestrial ecosystems and communities

2016

The Interim Biogeographic Regionalisation for Australia (IBRA; Figure BIO8) classifies Australia’s landscapes into 89 large, geographically distinct bioregions based on common climate, geology, landform, native vegetation and species information. The 89 bioregions are further refined to 419 subregions, which are more localised geomorphological units within each bioregion. The IBRA classification is used as a key planning tool for identifying land for conservation under the National Reserve System (Thackway & Cresswell 1995). It is used throughout this report to document the distribution of threatened species and communities and, in Effectiveness of biodiversity management, for understanding comprehensiveness, adequacy and representation of the National Reserve System.

In December 2015, 74 ecological communities were listed as threatened under the EPBC Act: 31 as critically endangered, 41 as endangered and 2 as vulnerable. (see Box BIO5) Thirty of these are new listings since 2011. EPBC Act–listed ecological communities are concentrated in south-eastern Australia (Figure BIO9). In particular, the Brigalow Belt IBRA region in Queensland, the Sydney Basin and Riverina IBRA regions in New South Wales, the Southern Volcanic Plain IBRA region in Victoria and the Murray–Darling Depression IBRA region all have high numbers of threatened ecological communities.

Box BIO5 Global and national lists of threatened ecosystems

Australia has maintained lists of nationally threatened species and ecological communities since 1992 (initially under the Endangered Species Protection Act 1992 and subsequently under the Environment Protection and Biodiversity Conservation Act 1999). Independently, the International Union for Conservation of Nature (IUCN) has maintained the IUCN Red List of Threatened Species since 1964 and, in 2008, initiated the global Red List of Ecosystems (Keith et al. 2013).

For the IUCN Red List of Ecosystems, there are 7 categories of risk that mirror those used for species (Figure BIO10). An additional category (collapse—CO) is assigned to ecosystems that have collapsed throughout their distribution, the analogue of the extinct (EX) category for species.

As at October 2016, assessment for 17 Australian ecosystems had been completed using the IUCN criteria; 3 were undertaken or led by the IUCN, and a further 14 were undertaken regionally in Australia.

An image of eight different-coloured circles representing the International Union for Conservation of Nature categories of risk, as described in the figure notes.

An image of eight different-coloured circles representing the International Union for Conservation of Nature categories of risk, as described in the figure notes.

CO = collapse; CR = critically endangered; DD = data deficient; EN = endangered; LC = least concern; NE = not evaluated; NT = not threatened; VU = vulnerable

Figure BIO10 International Union for Conservation of Nature categories of risk

Noisy pitta (Pitta versicolor) at Meunga Creek, Wet Tropics World Heritage Area, far north Queensland. Photo by David Westcott

Photo by David Westcott

Noisy pitta (Pitta versicolor) at Meunga Creek, Wet Tropics World Heritage Area, far north Queensland.

Jurisdictional reporting on vegetation condition and extent

Jurisdictions report on key trends in vegetation condition and extent. The assessment grade and adequacy of information, if given, are also noted. Trends in vegetation condition and extent are variable across the jurisdictions. Queensland and Victoria note declines in extent, whereas the Australian Capital Territory notes improvements in condition because of recovery from drought and land management activities.

Australian Capital Territory
  • Key trends in vegetation:
    • Grassland condition is relatively stable, although exotic species cover and richness increased towards the end of 2013–14.
    • General improvement in woodland condition is noted from 2004 to 2012–13, possibly as a result of recovery from drought, as well as land management activities.
    • Riparian condition along the Murrumbidgee River varies widely. In the areas covered by the National Reserve System, it is generally good; outside protected areas, condition is affected by rural land uses.
    • Exotic weeds are a pervasive feature.
  • Assessment grade and adequacy of information:
    • Connectivity of terrestrial native vegetation: status—good; trend—stable. Fine-scale modelling of existing fauna habitat and connectivity across the territory means that these values are now well understood.
New South Wales
  • Key trends in vegetation:
    • Clearing rates have been generally stable during the past 10 years.
    • Nine per cent of vegetation is close to natural condition.
    • Condition has generally deteriorated because of changed land use and land management.
  • Assessment grade and adequacy of information:
    • Clearing rate for woody native vegetation: status—moderate; trend—stable; information availability—good.
    • Extent of native vegetation: status—moderate; trend—stable; information availability—reasonable.
    • Condition of native vegetation: status—moderate; trend—increasing impact; information availability—limited.
    • Levels of pressure on native vegetation condition: status—moderate; trend—stable; information availability—limited.
Queensland
  • Key trends in vegetation:
    • Vegetation clearing rates in Queensland have been monitored since 1997 and reached a peak during 1999–2000, when about 0.4 per cent of the state’s remnant vegetation was cleared in 1 year.
    • Clearing rates have since decreased to reach 0.014 per cent per year of the state’s remnant vegetation in 2009–11, and then increased to 0.02 per cent per year in 2011–13.
    • In 2013–14, 296,324 hectares per year of woody vegetation were cleared statewide; this represented a 93 per cent increase from 2011 to 2012 and the highest woody vegetation clearing rate since 2006.
    • Pasture was the dominant replacement land-cover class, contributing to 92 per cent of the total statewide clearing.
    • Of the 16 broad vegetation groups statewide, 2 (mainly comprising acacia and eucalypt forests) have less than 60 per cent remnant native vegetation as at 2013.
  • Assessment grade and adequacy of information:
    • Knowledge of vegetation clearing rates—good.
Victoria
  • Key trends in vegetation:
    • The extent and condition of native vegetation in Victoria continue to decline, particularly through chronic degradation of habitat condition, mainly in fragmented landscapes.
    • Vegetation quality is generally stable on public land and in largely intact landscapes.
  • Assessment grade and adequacy of information:
    • Extent and condition of Victoria’s native vegetation: status—poor; trend—deteriorating.
    • Confidence in the assessment grade is given as fair, indicating limited evidence or consensus.
South Australia
  • Key trends in vegetation:
    • The area under some form of protected status has increased by about 10 per cent since 2008.
    • The area of revegetation has decreased since 2008.
    • At the end of 2013, 31 per cent of the 382 ecosystems in South Australia were classified as adequately protected (NRM report card).
  • Assessment grade and adequacy of information:
    • Native vegetation: status—poor; trend—deteriorating (EPA SA 2013).
    • Vegetation clearing: trend 1999–2014—stable; reliability of information on vegetation extent and connectivityvery good (NRM report card).
    • Native vegetation protection: trend—improving; reliability of information on protection of native vegetation—very good (NRM report card).
Western Australia
  • Key trends in vegetation:
    • The number of plant species discovered and described increased by an average of more than 50 per year, but there are still many to find.
    • Between 100 per cent and 0.55 per cent (average 78 per cent) of vegetation ecosystems in the south-west land division remain, compared with the pre-European extent.
  • Assessment grade and adequacy of information:
    • No assessment provided.
Tasmania
  • Key trends in vegetation:
    • From 2005 to 2015, the area of native vegetation in Tasmania decreased by 1.1 per cent. The total area of native forest decreased by approximately 42,000 hectares, and the total area of native nonforest vegetation decreased by approximately 15,000 hectares during this period.
    • Since 2009, a further 4 per cent of Tasmania’s native vegetation has been added to the National Reserve System in Tasmania, culminating in 54.5 per cent of native vegetation being reserved in 2015.
  • Assessment grade and adequacy of information:
    • These vegetation extent figures are based on existing datasets rather than a systematic change detection program. Comprehensive data will be available towards the end of 2016. The level of confidence in the extent and change of native nonforest vegetation is lower than for forest vegetation. This is primarily because of fewer requirements for recording clearing activity and greater difficulty in detecting change in nonforest vegetation using current methods.
Northern Territory
  • Key trends in vegetation:
    • The extent of clearing of native vegetation in the territory was estimated as 937,687 hectares (0.66 per cent of the land area) in 2004. Native vegetation extent has not been systematically monitored since then.
    • Between 2003 and 2015, an annual average of 5005 hectares of clearing of native vegetation was approved on pastoral land, and the rate of clearing on this tenure remained approximately constant during this period.
    • Land clearing has primarily occurred in the Daly Basin and Darwin Coastal bioregions, and on Melville Island.
    • Long-term systematic monitoring of vegetation structure and floristic composition in some conservation reserves has shown a decline in vegetation condition in some ecosystems, mostly associated with damaging fire regimes.
  • Assessment grade and adequacy of information:
    • There is currently no systematic remote monitoring of land-cover change in the Northern Territory.
    • Data are available for permits granted to clear native vegetation, but not all permit areas are ultimately cleared.
    • There is no standard methodology for assessing vegetation condition in the Northern Territory, and very limited systematic assessment and monitoring of vegetation condition.
    • The Pastoral Land Board reports on the condition of pastoral land in the Northern Territory, which is predominantly native vegetation. Pastoral land condition is currently monitored at 256 sites on 45 properties in 9 of the 11 pastoral districts. In 2014–15, 55 per cent of monitoring sites were assessed as in good condition, 25 per cent were fair, and 20 per cent were poor.

Extent of vegetation communities

The Land report details the current extent of vegetation communities across Australia. A summary is provided here.

A 2015 publication (Tulloch et al. 2015) assessed the relative change in vegetation extent and patch size in 75 Australian vegetation communities (as defined by the National Vegetation Information System 4.1). In Australia, 24 broad vegetation communities (32 per cent of the 75 evaluated) have lost at least 20 per cent of their original extent, and 7 communities (9 per cent) have lost more than 40 per cent of their original extent. Many of those most heavily cleared occur in the agriculturally productive coastal regions of Australia (Tulloch et al. 2015; Figure BIO11).

A net loss of about 1.4 million hectares of forest was recorded between 2005 and 2010 (Figure BIO12). This was primarily a result of land-use change for urban development and agriculture, as well as short-term factors such as fire and drought (MIG & NFISC 2013).

Quality of habitat

Most jurisdictions note that the condition of habitat is mostly in decline, although knowledge about vegetation condition is generally described as limited. The Australian Capital Territory notes some improvements in woodland condition between 2004 and 2012–13, possibly as a result of recovery from drought and land management activities.

An important implication of the loss of extent of vegetation is that ecological communities today have fewer larger patches of contiguous vegetation (Tulloch et al. 2015). For example, Brigalow Belt formerly extended across 96,492 square kilometres, distributed among 10,136 patches of vegetation. Today, this has been reduced by 87 per cent to 12,665 square kilometres distributed among 48,618 patches: a 4-fold increase in the original number of patches, despite the enormous overall decline in extent. At least 22 per cent of major vegetation communities in Australia have more than 50 per cent of their remaining extent in patches of less than 1000 hectares. Four ecological communities have at least 25 per cent of their remaining distribution in patches smaller than 10 hectares (open mallee woodlands, leptospermum forests and woodlands, eucalyptus tall open forest with fine-leaved shrubby understorey, and boulders or alpine fjaeldmarks). Despite 3 of these being naturally patchy (eucalyptus forest, leptospermum forests and boulders), this proportion has increased for all communities. Smaller patches of vegetation are subject to increased edge effects—that is, disturbance from surrounding land uses affects relatively more of the area of small patches. Small patches are more likely to be cleared, and small patches often have lower species diversity then larger contiguous patches.

Recent research has shown significant reductions in the abundance of large trees across a range of ecosystems globally, including in Australia. Large trees with cavities play a critical role in forest, agricultural and urban ecosystems, and their demise is an indicator of declining habitat quality, with impacts across many dependent fauna species. For example, long-term monitoring of large trees in mountain ash forests of south-eastern Australia has shown high rates of tree death primarily because of fire, and no recruitment of any new large trees. Large living and dead trees with cavities are a critical nesting and denning resource for more than 40 species of native vertebrates in mountain ash forests, including the endangered Leadbeater’s possum (Lindenmayer et al. 2012).

Ecosystem services

One major area of endeavour that has increased in importance and maturity has been the quantification of ecosystem services for NRM. Although the ecosystem services concept has been around for several decades in the scientific literature, legal frameworks and policy documents, efforts to apply the concept to quantify benefits from well-functioning ecological systems have improved substantially during the past 5 years or so (Pittock et al. 2012, Wentworth Group 2014). Furthermore, we have started to see the idea of ecosystem services taken up more and more into natural resource planning and management, and the establishment of targets for monitoring, reporting and evaluation of natural resources programs (e.g. National Action Plan for Salinity and Water Quality, Natural Heritage Trust, Caring for our Country).

During the past 5 years, multiple reports have proposed that ecosystem services become more commonly used, including within a ‘set of national accounts’. However, no system of assessment and reporting has seen major adoption (Cork 2011, Plant et al. 2012, BoM 2013, ABARES 2013, Wentworth Group 2014, ABS 2015). One regional example is that produced by the Australian Bureau of Statistics (ABS) for the Great Barrier Reef Region. The large body of scientific work undertaken in the region was connected with environmental and macro-economic indicators compiled by the ABS, to produce ‘experimental’ ecosystem accounts for agriculture, tourism, fishing and aquaculture (ABS 2015).

The Drivers report details efforts at the national and international level to improve environmental accounting.

Cresswell ID, Murphy H (2016). Biodiversity: Terrestrial ecosystems and communities. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra, https://soe.environment.gov.au/theme/biodiversity/topic/2016/terrestrial-ecosystems-and-communities, DOI 10.4226/94/58b65ac828812