An overview of recent native vegetation clearance in Australia and its implications for biodiversity
Biodiversity Series, Paper No. 6
Andreas Glanznig, Biodiversity Unit
Department of the Environment, Sport and Territories, June 1995
New South Wales
In the past 200 years, the landscapes and ecosystems of New South Wales have been substantially modified. The regions that have been mostly affected (apart from urban centres) are those that contain better soils on flat to undulating land. They include the coastal alluvial valleys and plains, basalt plateaux, the less steeply sloping tablelands and the Central Division which takes in the Western Slopes and eastern parts of the Western Plains (Benson 1991, p.346). The extent of these changes is shown in Figure 1. Based on information on pre-European forest cover contained in Carnahan's 1:5 million scale map of Australian Vegetation in the 1780s (AUSLIG 1990), the Resource Assessment Commission estimated that forest and woodland probably covered about 52 million ha or two-thirds of the State at the time of first European settlement. The other third consisted of open woodland, shrubland and native grassland ecosystems. Of the original 52 million ha of forest and woodland, only 21 million ha remain. Much of the forest and woodland has been totally cleared or converted to open woodland (RAC 1992; NSW Tree Forum 1993, p.4).
The pattern of native vegetation clearance varied over time. Between 1788 and 1921, early data indicates that 35.3 million ha were ringbarked and partially cleared in New South Wales (Statistical Register of New South Wales 1921 cited in Reed 1990, p.85; Reed 1991). This amounts to 44 per cent of the State. Most clearance occurred in the period 1893-1921 when about 25.7 million ha were ringbarked and partially cleared (Statistical Register of New South Wales,1892-1921 cited in Reed, 1990, p.85). Clearing was most intensive on the Western Slopes, Central Plains and Riverina (Beadle 1945; Reed 1990; Reed 1991). Comparison of this early data, however, with the contemporary figure of deforestation provided by the Resource Assessment Commission shows that the Statistical Register records significantly overestimated the scale of clearance.
Many coastal areas of New South Wales have been heavily modified by vegetation clearance. All major river valleys or plains have been extensively cleared. These include the Bega, lower Shoalhaven, Hunter, Clarence, Richmond and Tweed Valleys and the Cumberland Plain. In all these cases the plant and animal communities removed were generally unique to those valleys and which occurred on rich soils. The complete or near complete removal of native vegetation has resulted in their valley habitats being highly restricted in area and under considerable risk of further impacts (Dick 1995, pers comm).
In the Sydney region, for example, less than one per cent of the original Blue Gum High Forest remains, and less than 0.5 per cent of the Turpentine-Ironbark Forest. Together these two communities once covered 46 000 ha. About three per cent of each of the original 19 000 ha of River-flat Forest and 8000 ha of Eastern Suburbs Banksia Scrub are left. Of the Cumberland Plain Woodlands, existing fragments make up only six per cent of the former 107 000 ha while about 5000 ha of Castlereagh Woodland remain (D. Benson and Howell 1990).
In the Bega district on the South Coast, valley areas have lost most of their forested habitat. Many native animals are now rare. Four are considered to be in danger of extinction, and at least six species have become locally extinct since settlement (Lunney and Leary 1988).
As highlighted on page 8 by 1900 the extent of the Big Scrub lowland rainforest in the Richmond and Tweed districts had been reduced from over 75 000 ha to about 300 ha scattered over ten remnant patches (Floyd 1990; Floyd 1987).
Widespread vegetation clearance has continued in New South Wales. The areas most affected are a belt of land, 150 km wide, along the eastern and southern boundaries of the Western Division and the northern wheatbelt within the Central Division. Clearance is less extensive in the rest of the Central Division, the northern tablelands and along the coastal fringe but is threatening remnant vegetation and, as a result, biodiversity (J. Benson 1995, pers comm; Dick 1995, pers comm). Widespread clearing, however, stalled in the Western Division between 1991 and 1994 though land clearing applications have recently begun to be processed again.
No comprehensive State-wide records for monitoring the change of extent and status of native vegetation currently exist and consequently it is not possible to precisely document the scale or rate of recent vegetation clearance at a State level. At a regional level, however, the Department of Agriculture coordinates a Western Lands Monitor using Landsat remotely sensed data, to check actual clearing against clearing licences. To overview the pattern of recent vegetation clearance, information has been sourced mostly from the Australian Bureau of Statistics, the former Western Lands Commission and the New South Wales National Parks and Wildlife Service. While this information can indicate the overall pattern of recent native vegetation clearance it must be acknowledged that there are omissions.
At a State level, a number of coarse estimations have been undertaken for the rate of clearance. The most recent estimate of the clearance rate is 150 000 ha/yr based on a number of regional studies and personal observations (J. Benson, NSW Royal Botanic Gardens pers comm cited in NGGIC 1994, pp.129a-29b). Another estimate undertaken before the completion of a number of recent regional studies (eg. Sivertsen 1994) has been calculated as part of the Resource Assessment Commission Forest Inquiry. Data on clearing licences issued by the New South Wales Forestry Commission and Western Lands Commission suggest that the rates of deforestation since 1986 have been approximately 20 000 ha per year in the Eastern and Central Divisions and about 80 000 ha per year in the Western Division (Kestel Research and VICDCE 1990; RAC 1992, pp.G5-G6). In the 1980s and 1990s despite the decrease in the amount of vegetated land suitable for agricultural purposes and the recent economic downturn, substantial clearing has taken place.
While the estimated current rate is high compared with most other States, estimates of the pattern of clearance during the 1970s show that in the recent past it was significantly higher. On examination of clearance rates in New South Wales in five separate years between 1972 and 1980, the Australian Bureau of Statistics calculated that, on average, 430 000 ha were cleared each year, or 1100 ha per day. At the same time 168 826 ha of wetlands were modified through drainage which equates to 33 647 ha per year (ABS data cited in Reed 1990, p.87).
At a regional level, extensive clearing has until recently been occurring in the Western Division, which occupies about 320 000 km² or 40 per cent of New South Wales. While it is not possible to accurately estimate the overall extent of clearing, there is enough information to indicate the pattern of recent clearance. One general indicator for the Western Division is the amount of vegetation approved for clearance (as the Western Division is leasehold, landholders must apply to the Department of Conservation and Land Management for a licence to clear or cultivate) although licences generally overestimate the area actually cleared.
The majority of this clearing and cropping activity occurred in the higher rainfall parts of the Western Division within a 150 km wide belt of land along its eastern and southern boundaries, as illustrated in Figure 2.
In the period between January 1984 and November 1990, the former Western Lands Commission compiled information which shows that in the Western Division clearing licences were granted for a total area of over 640 000 ha (WLC data cited in Kestel Research and VICDCE 1990; Pressey 1990). The area permitted to be cleared and the dominant vegetation type affected is detailed in Table 4.
|Predominant tree community loss (ha)|
|Brimble Box/White Pine||Coolibah/Swamp Box||Mallee/Belah||Belah/Rosewood||Total|
|1984||100 822||35 464||54 798||3 922||195 006|
|1985||16 606||1 929||16 170||0||34 705|
|1986||45 006||19 551||5 607||0||70 164|
|1987||33 148||3 685||3 506||0||40 339|
|1988||60 294||41 726||18 205||8||120 233|
|1989||67 710||32 663||5 593||0||105 966|
|1990*||61 814||13 754||2 881||0||78 449|
|Total||385 400||148 772||106 760||3 930||644 862|
* Up to 19/11/90
The above table indicates areas for which clearing licences were issued, and does not necessarily represent area actually cleared. It is probable that the area actually cleared is significantly less.
Clearing licences are issued for a term of 2 to 4 years. It is likely that in some cases new licences have been granted over areas previously covered by licences that have expired.
The data covers the period 1/1/1984 to 19/11/1990 and refers to clearing licences issued during that period for leasehold lands in the Western Division of New South Wales (a total area of 32 million hectares).
Data courtesy of Western Lands Commission, NSW.
Source: WLC data cited in Kestel Research and VICDCE (1990, p.49)
The table also incorporates data on licences issued for tree thinning rather than broadscale clearing per se. This is particularly the case for licences issued to thin coolibah/swamp box communities where tree stem density has increased significantly since European settlement. These changes have been attributed mainly to grazing and altered fire regimes (Pressey 1995, pers comm).
Furthermore, over the period 1978 to 1990, approximately another 650 000 ha of natural grasslands, scrublands and previously cleared lands were approved for intensive cropping activities (WLC, Departmental records (1978-1990) cited in Dick 1992, p.14).
Widespread clearing in the Western Division stalled in 1991 due to the economic downturn, serious drought and the need for the Department of Conservation and Land Management (CALM) to assess its responsibilities under the New South Wales Endangered Fauna (Interim Protection) Act 1991. CALM has now developed a new assessment procedure and applications are again being processed (Dick 1995, pers comm).
Widespread clearing is still possible in the Western Division, as the landscape remains predominately wooded. The intent of lessees to continue clearing is reflected in a CALM survey of lessees in the mallee belt in the southern part of the Western Division. The survey results show that lessees would like to clear the mallee woodlands at rates similar to those of the early 1980s for at least another five years (Hassall and Associates 1991).
In the Central Division or wheat belt of New South Wales, about 90 per cent of the native vegetation has been cleared (Dick 1995, pers comm) and remnant vegetation continues to be cleared at a substantial rate. Most plant communities in this area are considered threatened (J. Benson 1991).
A study being undertaken by the New South Wales National Parks and Wildlife Service to map the remaining native vegetation in the wheatbelt of New South Wales has produced data on clearing rates for woody native vegetation between 1977 and 1984-85 in the St George and Moree areas, and an area extending south from the MacIntyre River in the vicinity of the Queensland border town of Goondiwindi (see Figure 3).
Based on a comparison of maps produced by the interpretation of aerial photographs, the study found that in just eight years nearly 70 per cent of all the remaining native woody vegetation was cleared from the area covered by the Goondiwindi map. This leaves only about 19 per cent of the area supporting native vegetation. While the area south of Goondiwindi is the most affected, it is considered that trends are similar for the whole study area and, if these trends continue, it can be expected that remnant native vegetation will be virtually cleared from the area by the turn of the century (Sivertsen 1994).
Another localised survey undertaken in the Condobolin area found that in 1974 an area of about 94 400 ha remained. In 1989 this had been reduced by 57 400 ha, or 61 per cent in a space of 15 years (Sivertsen 1992).
In addition to the impacts of direct vegetation clearance, the poor state of health of many remaining tree stands (as evidenced by the degree of dieback and the extent of regeneration) will lead to a significant loss of trees in the medium term.
The Eastern Division is also subject to significant clearance, particularly the area encompassed by the Northern Tablelands and the coastal zone. In the Northern Tablelands many parcels of low fertility land (such as granites and sandstones) are now being cleared by hobby farmers (J. Benson 1995, pers comm).
The coastal zone of New South Wales is also being impacted, mainly through the rapid development of non-metropolitan areas. The last 20 years has seen a rapid occupation of areas which were previously unoccupied or incurred very low levels of development. The overall rise in the population throughout the zone has led to only three 10 km long sections of the New South Wales coast having no occupants. Two areas which previously contained small towns, Tweed Heads and Port Macquarie, now have major urban population levels and this trend is being followed by Ballina, Coffs Harbour and Forster-Tuncurry.
In general, the North Coast has shown a very patchy but intense growth pattern while the South Coast has exhibited a consistent increase in population, peaking and centred around the town of Batemans Bay (Hamilton and Cocks 1994). The environmental impacts of this growth has resulted in substantial disturbance of ecosystems and the loss and fragmentation of habitats (Hamilton and Cocks 1994; Crome, Foran and Moore 1994).
Impacts on native vegetation caused by development in metropolitan areas are also continuing. For example, in Western Sydney bushland remnants are increasingly threatened by the expansion of suburban areas (D. Benson and McDougall 1991). Coastal wetlands also continue to be affected; even though the State Environmental Planning Policy No. 14 has limited further destruction of wetlands and Melaleuca swamps, some areas are still being reclaimed for canal estates or agriculture (J. Benson 1995, pers comm).
While the general trend is towards a continued net loss of native vegetation, some areas of New South Wales are experiencing regrowth on previously cleared land; this includes the coastal zone, and the tablelands and western plains in some locations (J. Benson 1995, pers comm).