NSW State of the Environment 2012

SoE 2012 > Biodiversity > 5.2 Native vegetation

Biodiversity chapter 5

5.2 Native vegetation

Sixty-one per cent of New South Wales is covered by native vegetation. Of this, only 9% of NSW has vegetation considered to be in close to natural condition, whereas condition has deteriorated in the remaining 52%. Land use and land management have had an impact on the condition and function of native vegetation. Levels of vegetation clearing have stabilised over the past six years.

Land clearing has been recognised as the main threat to the extent and condition of native vegetation in NSW. While some vegetation classes, particularly woodlands and grasslands, have been substantially depleted since European settlement, others remain largely intact.

The clearing of native vegetation has been greatest in areas preferred for urban development (the coastal plain) or agricultural development (the wheat–sheep belt of central NSW).

Over the past nine years, the overall area of woody vegetation has remained relatively stable, but in the longer term positive gains in the overall extent and condition of native vegetation are expected as current programs take effect.

Vegetation condition largely reflects the primary land use and is being addressed through better land management practices. However, pressures on condition are likely to remain for the foreseeable future, due to the long-term effects of fragmentation following clearing, coupled with increasing pressures from invasive species and climate change.

NSW indicators

Notes: Terms and symbols used above are defined in About SoE 2012 at the front of the report.

Introduction

NSW contains a great variety of native vegetation, with outstanding examples of rainforests, eucalypt forests and woodlands, grasslands, wetlands, coastal heaths, alpine habitats and arid shrublands. Native vegetation provides essential habitat for plant and animal species, and is an integral component of healthy, functioning ecosystems.

Native vegetation extent and condition are indicators of ecosystem health and diversity (Saunders et al. 1998). While generalised mapping based only on vegetation structure and growth form provides a useful overview for reporting on the statewide status and extent of native vegetation, it is less descriptive of ecosystems. More detailed vegetation mapping based on information about species composition provides a better practical indicator of the location and status of ecosystems. However, the description in this section is largely based on generalised mapping as more detailed mapping is not consistently available across the state.

Status and trends

Vegetation extent

A dataset on the extent of NSW native vegetation was prepared under the NSW Natural Resources Monitoring Evaluation and Reporting Strategy 2010-2015 (DECCW 2010d) using a compilation of vegetation mapping and remote sensing analysis (Dillon et al. 2011). This described the extent of native vegetation in four 'extent modification categories' which represented various levels or degrees of modification and was presented as Map 7.1 in SoE 2009 (DECCW 2009a). The four extent modification categories shown were:

• native – intact: native vegetation in which the structure has not been substantially altered
• native – derived: vegetation that is predominantly native but is no longer structurally intact as it has been substantially altered and is missing important structural components or layers
• native/non-native mosaic: vegetation that cannot be classified as native or non-native using current remote sensing technologies
• non-native/other vegetation types: non-native vegetation (crops, plantations, pasture) or other non-vegetative land cover.

This earlier map has now been combined with the latest map of change in woody vegetation. 'Woody' vegetation is vegetation that is over two metres tall with a canopy cover of more than 20%. All other vegetation is described as 'non-woody'. Whether native vegetation is woody or non-woody affects how it is monitored and hence the quality of the information available on vegetation clearing in different areas and the change in its extent (see 'Pressures'). Information is generally more reliable for woody vegetation as it is easier to monitor by satellite.

Map 5.1 depicts the location and extent of native vegetation that is woody or non-woody in each of the extent modification categories.

Map 5.1: Extent of woody and non-woody native vegetation in NSW in various states of modification

Extent of woody and non-woody vegetation by extent modification category

The data extracted from Map 5.1 indicates the changes affecting native vegetation modified to various levels in NSW and the confidence in this information, which is greater for woody vegetation. The results are shown in Table 5.4.

Table 5.4: Proportion of extent modification categories that is woody or non-woody

Notes: * This is not the total area of NSW: the analysis excluded an area of metropolitan Sydney which was not assessed.

Table 5.4 shows that 45% of all native vegetation in NSW is woody and 55% non-woody. However, this pattern is reversed for intact native vegetation, where the proportion of woody vegetation is greater (55%). Most derived and mosaic vegetation is therefore non-woody, reflecting the significant changes that have occurred to native vegetation in NSW.

The most extensive changes have been to native grasslands, most of which no longer exist as natural grasslands, and to grassy woodlands, where removal of the tree layer has created non-natural (not naturally occurring) grasslands. While the overall area of grasslands has probably now increased, most are not naturally occurring and do not consist of vegetation that can be categorised as intact native vegetation.

Extent of intact native vegetation

'Native – intact' vegetation covers 61% of NSW. As native vegetation in this category retains its structural integrity, naturally occurring vegetation communities can still be identified (Keith & Simpson 2006; Keith & Simpson 2008), but these communities are not necessarily in good condition. Much of the vegetation in this category faces a range of impacts on its condition from a variety of land uses, including changes to species composition and ecological function, reduced vigour or regeneration, and diminished habitat values. Only 9% of native vegetation in NSW is regarded as being in close to natural condition as it is managed with conservation as the primary objective and is therefore not subject to land-use pressures.

The current extent of intact native vegetation in NSW reflects differing rates of clearing across various parts of the state. Generally, flat productive lands have been favoured for development, with particularly high rates of clearing in native grasslands, grassy woodlands, some types of wetlands and eucalypt forests. Some other native vegetation formations, such as arid shrublands and alpine areas, occur on land that is less attractive for development and so have experienced little change in extent. Table 5.5 summarises the status of a range of intact native vegetation formations.

Table 5.5: Extent of clearing of native vegetation formations in NSW since 1750

Source: Keith 2004

Extent of modified native vegetation

Modified or 'derived' native vegetation covers 8% of NSW. Although the structure of derived native vegetation has been deliberately modified, more than 50% of the vegetation cover is composed of native species, so it still makes some contribution to overall native habitat values in NSW (DECC 2008b).

Vegetation described as 'native/non-native mosaic' (see Map 5.1) covers 20% of NSW and contains a mixture of native and non-native vegetation which cannot be distinguished, so this category could be regarded as indeterminate (DECC 2008b). Much of this vegetation is grassland used for grazing and the inability to categorise it reflects the less advanced state of monitoring of non-woody vegetation.

Vegetation condition

Where native vegetation has not been cleared, its condition ranges from pristine when undisturbed to heavily degraded. Between these two extremes, the condition of native vegetation may be modified to varying degrees by land management practices and unplanned threats such as weed invasion, drought and fire. The negative impacts of these threats include:

• changes to the structure, ecological function and species composition of native vegetation
• lower rates of regeneration and reduced vigour
• the prevalence of parasites and diseases
• the presence of weeds and pests.

The combined effect of these impacts diminishes habitat values and impairs ecosystem processes. Decline in vegetation condition is generally less visible than clearing and occurs over a longer time frame. It is therefore more difficult to detect and assess.

A broad assessment of vegetation condition, largely based on generalised land use where vegetation condition declines with an increase in land-use intensity, was presented in Map 7.2 of SoE 2009 (DECCW 2009a). The map described the broad transformation that occurred to the structure of vegetation across the landscape when it was modified to make land suitable for a range of human uses, but it is static in nature and can only be updated if a further major land-use change occurs.

A more detailed analysis which incorporates site survey data on the condition of vegetation and relates it to land use and present land management practices is being developed, but this is not yet available statewide. This analysis will better reflect ongoing changes to vegetation condition that are produced by improved land management practices than the static map of land use described above.

Pressures

Vegetation extent

Land clearing

Native vegetation has been extensively cleared in NSW for settlement, industry and agriculture. Clearing facilitates land-use change and is generally irreversible due to the ongoing nature of the subsequent uses of cleared land. The process of clearing actively displaces many native animals and plants and has a negative impact on biodiversity. Over time, through the effects of fragmentation and disturbance, it leads to weed invasion and further deterioration in the condition and habitat values of the vegetation that remains.

Clearing is therefore accepted as being the main cause of vegetation change and decline. Clearing of native vegetation, and associated destruction of habitat has been identified as the process representing the greatest single threat to biodiversity in NSW (Coutts-Smith & Downey 2006). Land clearing is also listed as a key threatening process under both the Threatened Species Conservation Act 1995 and Environment Protection and Biodiversity Conservation Act 1999 (Cwlth).

However, not all clearing occurs through the direct removal of vegetation. Much of the native grassland in NSW has been cleared or modified by pasture improvement, through the application of fertilisers, and by the ploughing and sowing of introduced grasses and clovers. Some freshwater wetlands and arid shrublands have also been cleared, in effect, by prolonged overgrazing.

Clearing of woody vegetation

The annual record of woody vegetation change is produced by analysing Landsat remote sensing data using the SLATS methodology, developed in Queensland (DNRW 2007). This record provides an indication of the rate of clearing of woody vegetation, which is vegetation that is over two metres in height with a canopy cover of 20% or more. Generally, woody vegetation is found in forests and woodlands.

The SLATS methodology identifies changes in the extent and structure of woody vegetation that are due to agriculture, infrastructure development and forestry. Figure 5.5 presents data on these changes.

Figure 5.5: Woody vegetation change in NSW, 1988–1990 to 2010–2011

Source: Office of Environment and Heritage (OEH) data 2011

Notes: Until 2006–2007, the annual rate of clearing was derived from change detected over a two-year period (for example, 1988–1990 represents two years from around the end of 1988 to around the end of 1990) with the value averaged over the two years. From 2006–2007 onwards, assessments have been conducted yearly.
There is some variability in the actual length of the two-yearly or yearly intervals, depending on the availability of remote sensing data suitable for analysis due to seasonal factors.

The estimate of clearing discussed in this report relates only to activities that lead to permanent changes in land use and landscape function, that is, changes due to agriculture and infrastructure development. Since 2005, the clearing of woody vegetation has been relatively stable, fluctuating around the long-term combined average for agriculture and infrastructure of about 23,400 hectares per annum. However, in the last period of monitoring for which data is available (2010–2011) it dropped sharply to around 9000 hectares. Most of the recent clearing has been in the wheat–sheep belt, along the eastern fringe of the semi-arid zone (DLWC 2002; Keith et al. 2009; OEH 2011a).

Forestry operations have not been included as clearing because they do not lead to land-use change. Most of the areas where change is detected due to logging are expected to be regenerated as regrowth forest. A spike in forestry activity is evident in the data since 2006–2007, with levels in subsequent years above the long-term average of about 15,600 hectares per annum. However, this trend had begun to decline in 2010–2011, the final year for which data is available.

Monitoring of revegetation is inherently more complex than monitoring of clearing. A preliminary analysis in 2009 appeared to show that the overall level of woody vegetation has been stable since 2003, with clearing being balanced by regrowth, revegetation and restoration. However, further work is needed before a detailed interpretation of this result is possible.

Clearing of non-woody vegetation

Non-woody vegetation is generally all vegetation that does not meet the criteria to be classified as woody vegetation. It refers to all grasslands and large areas of open woodlands and arid shrublands characteristic of western NSW, where densities of trees and shrubs are below the threshold of reliable detectability by the SLATS methodology. As discussed previously, 55% of all vegetation is non-woody, but it is difficult to detect change in this type of vegetation or monitor clearing of it. The processes and dynamics that affect change in non-woody vegetation are different from those affecting woody vegetation so it is not possible to use woody vegetation data to draw conclusions about the clearing of non-woody vegetation. All that is known about the overall level of clearing of all vegetation in NSW is that it is likely to be somewhat greater than the annual level of clearing detected for woody vegetation.

Vegetation condition

Land use

Map 5.2 shows the levels of pressure from a variety of land uses on vegetation extent and condition. The land uses themselves are described in Guidelines for Land Use Mapping in Australia: Principles, procedures and definitions (ABARES 2011). They have been reclassified into five categories of inferred pressure that describe the generally increasing levels of disturbance to native vegetation as the intensity of the operations or processes associated with a primary land use increases.

The five land-use pressure categories are:

• conservation and natural environments – land set aside primarily for conservation, where natural ecosystems are maintained
• relatively natural environments – land used primarily for agriculture, with limited changes to native vegetation
• dryland agriculture and plantations – land used mainly for agriculture, based on dryland farming
• irrigated agriculture and plantations – land used mostly for agriculture, based on irrigated farming
• intensive uses – land subject to extensive modification, generally in association with residential settlement, or commercial or industrial uses.

Map 5.2: Land-use pressure on the extent and condition of NSW native vegetation

General pressures

Not all the pressure on vegetation is due to land use. Table 5.6 summarises the main pressures affecting vegetation condition, the number of vegetation classes affected and the general changes to condition that have occurred over the past decade.

Assessment of the pressures is based on how many of the 99 NSW vegetation classes defined by Keith 2004 are affected. This assessment broadly indicates the extent of the pressure but not necessarily its intensity or significance. For instance, land clearing and the fragmentation that results is the most severe pressure but it affects only 60 vegetation classes, whereas climate change affects all 99 classes, invasive species 95, altered fire regimes 84 and soil degradation 86.

Table 5.6: Changes to pressures on NSW native vegetation, 2002–12

Source: OEH data 2012

Notes: Totals across columns may not add up to 99 (the total number of vegetation classes) as not all vegetation classes are affected by all pressures.
* Severity refers to the intensity of the pressure and is not necessarily related to the number of classes affected. For example, the effects of land clearing are more severe but affect fewer classes than invasive species, which are more pervasive.

Table 5.6 demonstrates that over the past 10 years most pressures have been ongoing with little sign of abatement. There are relatively few instances where pressures are easing and most are either intensifying or stable. The main reasons for intensifying pressures are:

• changes in flows due to river regulation, compounded by a severe drought cycle during most of the past decade (2002–2010)
• climate change
• the appearance in 2010 of myrtle rust, a new fungal pathogen that threatens forests on the east coast.

The impacts of land clearing on habitat have been discussed in 'Vegetation extent'. However, habitat fragmentation caused by clearing continues to have long-term impacts on native vegetation well after the initial clearing occurs, primarily through dieback, invasions of weeds and feral animals, and loss of native species.

Changes to water regimes, combined with a particularly severe drought until 2010 (see Water 4.1 and Water 4.2) resulted in extensive dieback in floodplain forests and woodlands and this was compounded by the impacts of salinisation in the lower Murray–Darling Basin.

Climate change is pervasive and is expected to have increasing effects on all classes of vegetation in NSW. Alpine vegetation, wetlands and rainforests are likely to be especially sensitive (Laurence et al. 2011). The continuing reduction in snow cover in alpine habitats (Nicholls 2009) is decreasing the area and suitability of habitat for a range of specialised alpine species (Green & Pickering 2009).

While most arid shrublands and grasslands are not subject to extensive clearing, they are affected by overgrazing, which represents the cumulative impact of native species, farm stock and feral pest animals. The effects of overgrazing have been compounded by the drought cycle from 2002–2010, which reduced the cover of ephemeral plants. Overgrazing simplifies fauna habitat and promotes an overabundance of species which are less palatable to grazing animals.

Other significant and pervasive pressures affecting vegetation condition are discussed as separate issues in this report. These include soil degradation (Land 3.1), invasive species (Biodiversity 5.4) and fire (Biodiversity 5.5).

Responses

Established responses

NSW 2021

NSW 2021: A plan to make NSW number one (NSW Government 2011) is the Government's 10-year plan for NSW. Under Goal 22 – 'Protect our natural environment', the plan contains the following target: 'Protect and conserve land, biodiversity and native vegetation' which will be achieved through the following strategies:

• 'Identify and seek to acquire land of high conservation and strategic conservation value for permanent conservation measures'
• 'Establish voluntary arrangements with landowners over the next decade to bring an average 20,000 hectares per year of private land under conservation management and an average 300,000 hectares per year of private land being improved for sustainable management'.

The priority actions associated with this target are to 'work with catchment management authorities and local community groups to protect and improve habitats on private lands'. Actions to conserve biodiversity and native vegetation include:

• 'Regenerate degraded natural bushland, including riverbanks, and degraded waterways through a $10-million fund'
• 'Purchase and protect strategic areas of high conservation value and ensure more green spaces across Sydney and NSW through the $40-million Green Corridors Program'.

These targets and activities are described in greater detail under 'Responses' in Biodiversity 5.1.

Native Vegetation Act

The Native Vegetation Act 2003 (NV Act) is the key legislation regulating the clearing of native vegetation in NSW. The Act came into effect in December 2005 and aims to prevent broadscale land clearing unless it maintains or improves environmental values. The Act regulates the clearing of native vegetation in most of NSW, except on land in urban areas and land excluded for major development, and in national parks, conservation areas, state forests and reserves.

The Government is presently reviewing the Native Vegetation Regulation 2005 and various other provisions under the NV Act, including the Environmental Outcomes Assessment Methodology (EOAM) and Private Native Forestry Code of Practice. The review is intended to cut red tape and simplify requirements, while still protecting native vegetation, soil, land and water.

Catchment action plans

Catchment management authorities (CMAs) play a central role in delivering programs to protect, maintain or improve native vegetation. They are responsible for developing catchment action plans (CAPs) which establish regional priorities for natural resource management and coordinate the delivery of programs at the regional level. More information on the role of CMAs is provided in Biodiversity 5.1.

Property vegetation plans

The provisions of the NV Act are largely implemented through a framework of voluntary agreements called property vegetation plans (PVPs), which only permit clearing on properties if environmental values are maintained or improved. PVPs are based on maintaining or improving outcomes under four criteria in the EOAM: biodiversity, soil health, water quality and soil salinity. CMAs play a pivotal role in establishing PVPs with private landholders.

A range of other measures to improve landscape management, enhance the condition of native vegetation and maintain biodiversity are also implemented through PVPs. For example, special protection is provided for landscape and vegetation types that have been cleared to below 30% of their original extent, and measures are in place to reward landowners for voluntary conservation activities. Other activities are described under 'Restoration or revegetation of native vegetation' and 'New management of native vegetation' in Table 5.7.

Management of native vegetation

Since 2006, the NSW Government has been collecting data on native vegetation programs from various agencies to produce a native vegetation 'report card' for publication in the NSW Annual Report on Native Vegetation (OEH 2011a). Table 5.7 shows the extent of activity in the following categories:

• New conservation areas
• Restoration or revegetation of native vegetation
• New management of native vegetation
• New clearing of native vegetation.

The first three categories affect the extent or condition, or both, of native vegetation positively, while the last category describes approved losses in the extent of vegetation. Table 5.7 reports on the most recent three-year period and also provides cumulative totals since data was first collected in 2006.

Table 5.7: Native vegetation report card – area of land where actions to protect or manage native vegetation in NSW have occurred

Source: OEH and Department of Primary Industries data 2011

Notes: All areas are shown in hectares.
There may be some differences between individual figures and overall totals due to rounding.
* Cumulative totals for the previous years of reporting shown.

In general, the total area of land being conserved, restored or undergoing improved management is substantially greater than the area approved for clearing. However, while the areas to improve the condition or management of native vegetation are quite substantial it is still too early for most of the measures listed in Table 5.7 to be detectable as changes in vegetation extent or condition.

Reservation

Figures for new conservation areas (Table 5.7) represent additions to the public and private reserve system. A dedicated public system of parks and reserves is the cornerstone of conservation programs to preserve biodiversity and protect native vegetation (see Biodiversity 5.3). These areas are protected from clearing and will be managed for conservation in perpetuity. About 8.8% of all land in NSW has been incorporated into the reserve system, including the newly proclaimed Dharawal National Park in March 2012. Sufficient representation of all vegetation formations and classes is a key consideration in planning the future development of the reserve system (see Table 5.9 in Biodiversity 5.3).

Greater importance is now being placed on conservation across whole landscapes and protection in the reserve system is increasingly being supplemented by measures promoting conservation on private land (see Biodiversity 5.3). The NSW Government is implementing the Great Eastern Ranges Initiative and Green Corridors Program to further advance these objectives.

Restoration and revegetation

'Restoration or revegetation of native vegetation' in Table 5.7 refers to measures to improve the condition of native vegetation or increase its extent in NSW. These include incentive PVPs and PVP offsets, CMA-funded programs and other initiatives. Restoration of native vegetation is undertaken to improve the condition and habitat values of existing vegetation, while revegetation aims to increase the extent of native vegetation. Undertaken strategically, revegetation can buffer existing reserves, provide wildlife corridors and reduce fragmentation of the landscape. There has been a major and sustained increase in revegetation since the implementation of the NV Act and PVP framework in 2005.

New management of native vegetation

'New management of native vegetation' in Table 5.7 describes activities undertaken to enhance the condition of vegetation, such as the clearing of invasive native scrub, removing weeds and regulating private native forestry. NSW 2021 has a strong focus on regenerating bushland by improving the management of private land to enhance and maximise its environmental values and by supporting CMAs in involving local communities and landholders. Actions include protecting areas that are sensitive or have high conservation value by fencing, weeding, and other measures that address specific ecosystem, habitat or species needs.

Regulating clearing of native vegetation

Under the NV Act, clearing is not permitted on properties unless it improves or maintains environmental values. A system of offsets has been introduced which allows landowners to clear native vegetation, provided they agree to plant, improve, or better manage other vegetation on their own property or elsewhere. The offsets required are described under 'Restoration or revegetation of native vegetation' in Table 5.7, while the areas permitted to be cleared are reported on in the 'New clearing of native vegetation' category.

Compliance and enforcement

The Native Vegetation Compliance and Enforcement Strategy (DECCW 2009b) has been developed by the NSW Government to promote compliance with the NV Act and assist with community understanding of its provisions and requirements. Remote sensing technologies have been used extensively to enable statewide monitoring and reporting. There have been a number of successful prosecutions for breaches of the NV Act through illegal clearing.

Future opportunities

Regional programs involving local communities should provide more opportunities to improve vegetation condition, enhance habitat connectivity and reduce fragmentation which will, over time, lead to the increasing resilience, health and productivity of all native vegetation types on public and private land.

A framework to record natural resource management activities and works delivered regionally has been established. This will provide better alignment between program objectives and overall outcomes, enhancing the capacity for adaptive management and providing better information and support to guide local community involvement.

Although clearing may be slowed and fragmentation reduced, the pressures that affect vegetation condition are likely to continue in future, due to further weed invasion and new weed incursions, the effects of plant diseases and pathogens, and the effects of climate change and related changes to fire regimes.