• Change text size
• Skip to content

• About us
• Contact us

Environment home

• SoE
• About SoE reporting
• SoE 2011
• SoE 2006
  • SoE 2006 report
  • SoE2006 at a glance
  • Theme commentaries
  • Integrative commentaties
  • Current or emerging issues
  • Technical reports
  • Data Reporting System
• SoE 2001
  • Report
  • Key findings
  • Fact sheets
  • Theme reports
  • Technical papers
• SoE 1996
  • SoE 1996 report
  • Key findings brochure
  • Technical papers
• Publications

SoE themes

• Atmosphere
• Biodiversity
• Coasts & oceans
• Human settlements
• Inland waters
• Land
• Natural & cultural heritage
• Australian Antarctic Territory

Indicator: LD-17 Fragmentation of remnant vegetation

Data

Number of subregions in fragmentation classes

Remnant class	Plant isolation index class 1 >60% of total vegetation fragments	Plant isolation index class 2 30-60% of total vegetation fragments	Plant isolation index class 3 30-10% of total vegetation fragments	Plant isolation index class 4 <10% of total vegetation fragments	Number of subregions in each remnant class
1 < 30%	4	18	18	2	42
2 30-70%	0	0	28	51	79
3 > 70%	0	0	0	233	233
Number of subregions in each plant isolation index class	4	18	46	286

Source: National Land and Water Resources Audit 2001, Fragmentation of Australia’s Native Vegetation: Applications, Australian Native Vegetation Assessment 2001. Page 113, Table 26 and Figure 32

• Fragmentation of Australia's native vegetation: applications 
• Fragmentation of Australia's native vegetation: applications (Word - 841 KB) 

• Fragmentation of Australia's native vegetation: applications (Word - 841 KB) 

What the data mean

The analysis in the NLWRA’s Australian Native Vegetation Assessment 2001 used fragment sizes of less than 1000 hectares as a proportion of the total area of native vegetation remaining in each IBRA sub region.

Of 42 sub regions with less than 30% of vegetation remaining (out of a total of 354 sub regions), 22 were highly fragmented. These sub regions occur in south western Western Australia, south eastern South Australia, southern to central eastern Queensland and throughout Victoria and eastern NSW. Not surprisingly, they roughly parallel the area of Australia that was originally under forest or woodland, and the area where the majority of land clearing has occurred.

Data Limitations

This analysis was undertaken by the National Land and Water Resources Audit in 2001. No further assessments have been undertaken to indicate trends since then.

The methodology is one of several that might have been used. Different size cut-offs might be applicable to different purposes. The interpretation of patch size is also dependent on the scale of the mapping and minimum mapping area. The data are best read in conjunction with the data on the extent of native vegetation in the subregion (and where most of it is in relation to the fragments) and along with data on tenure and land use.

Shape and size of fragments, distance between fragments and distance from the nearest larger area of vegetation have not been factored into this analysis although further analysis of some fragment examples was undertaken by the NLWRA and are discussed in the source document.

Issues for which this is an indicator and why

Land - Land condition - Condition of terrestrial species and ecological communities 

While the gross area of vegetated land remaining is one indicator of the condition of the land and its biodiversity, the health and resilience of that remaining vegetation is also largely dependent on the size of the fragments and their proximity to each other.

Fragmented patches of vegetation may be the only remaining examples of particular vegetation groups or ecosystems in a region. They may also provide a source for any revegetation or restoration activities. The smaller and more isolated the remnants, the less viable and more vulnerable are the plants, animals and other biodiversity inhabiting them to external pressures as their boundaries (representing a significant proportion of their total area) are exposed to disturbances.

Other indicators for this issue:

• LD-01 The proportion and area of native vegetation and changes over time 
• LD-03 Change in extent and proportion of woody vegetation, clearing and regrowth 
• BD-02 Conservation status of nationally significant species and ecological communities, compared with previous years 

Land - Land condition - Land cover 

While the gross area of vegetated land remaining is one indicator of the condition of the land and its biodiversity, the health and resilience of that remaining land cover is also largely dependent on the size of the fragments and their proximity to each other.

Fragmented patches of vegetation may be the only remaining examples of particular vegetation groups or ecosystems in a region. They may also provide a source for any revegetation or restoration activities. The smaller and more isolated the remnants, the less viable and more vulnerable are the plants, animals and other biodiversity inhabiting them to external pressures as their boundaries (representing a significant proportion of their total area) are exposed to disturbances.

Other indicators for this issue:

• LD-01 The proportion and area of native vegetation and changes over time 
• LD-03 Change in extent and proportion of woody vegetation, clearing and regrowth 

Land - Direct pressure of human activities on the land - Land clearing 

While the gross area of land cleared is one indicator of the pressure of vegetation removal on the land’s general condition, the health and resilience of the vegetation that remains are also largely dependent on the size of the fragments and their distance from each other.

The smaller and more isolated the remnants, the greater the threat from external pressures as their boundaries (representing a increasing proportion of total area with decreasing fragment size) are exposed to disturbances Pressure also increases with the distance to be traversed to other refugia by animals (including pollinators), seeds, soil nutrients etc.

Other indicators for this issue:

• LD-01 The proportion and area of native vegetation and changes over time 
• LD-03 Change in extent and proportion of woody vegetation, clearing and regrowth 
• LD-20 Total grazing pressure relative to net primary productivity 
• BD-13 Examples of the impact of grazing on biodiversity 

Biodiversity - Pressures on biodiversity - Land clearing 

Fragmentation of habitat as a result of land clearing places further pressure on serving biodiversity, isolating populations from sources of recruitment and intensifying competition for remaining niches.

Other indicators for this issue:

• LD-01 The proportion and area of native vegetation and changes over time 
• BD-08 Estimated loss of biodiversity resulting from land clearing 

Inland Waters - Catchment scale influences - Land and vegetation condition - Vegetation 

Fragmentation of vegetation, especially along inland water courses is compounds other pressures impacting on vegetation condition.

Other indicators for this issue:

• IW-26 Forested streamlength 
• IW-34 Examples of deterioration of condition of wetland vegetation 
• LD-01 The proportion and area of native vegetation and changes over time 
• LD-03 Change in extent and proportion of woody vegetation, clearing and regrowth 

Further Information

Extensive additional analysis of vegetation data are available in the source document and also in the NHT publication “Landscape Health in Australia”. The primary source of the data used in these reports in the National Vegetation Inventory System.