Australian Native Vegetation Assessment 2001
Maria Cofinas, Colin Creighton
National Land and Water Resources Audit, 2001
ISBN 0 642 37128 8
Knowledge, data and information gaps
Spiranthes australis near Braidwood, NSW
Photo: Robin Jean
Continuing to consolidate management relevant information on Australia's vegetation
The Audit focused on the collation of existing information on the type and extent of pre-European and present native vegetation. This included the compilation of data in areas of Australia with existing mapping which may not meet the nominal required scale, currency and level of classification, to ensure the maximum amount of information was compiled.
The goal of the data compilation was to meet information requirements for vegetation management, land use pressures and threats to vegetation identified in the National Land and Water Resources Audit Needs Analysis Report in 1998. Marine, riparian and wetland vegetation mapping, the assessment of native vegetation condition and information covering the external territories were excluded due to time, resource and data constraints.
Compilation of data and information into the National Vegetation Information System has highlighted a number of gaps in information and data coverage based on nominal thresholds:
- thematic (information and knowledge) gaps;
- spatial (scale and geographic coverage) gaps;
- currency (date) of mapping;
- vegetation classification level gaps; and
- reliability of survey and mapping methods.
Thematic gaps
Gaps in the knowledge of native vegetation in Australia has not been systematically assessed and documented. Information presented is based on a general assessment of major gaps and should be further investigated in consultation with scientific experts, policy officers and landholders.c
Grasslands
- Difficult to interpret using aerial photograph interpretation techniques; site surveys are very costly.
- Limited data where regions have been mapped for the upper storey vegetation.
- Not comprehensively mapped or surveyed for the ground layer (e.g. grassy woodlands and grasslands and where regions of native and modified grasslands have not been comprehensively surveyed down to a Level V classification (vegetation association).
- Standards and methods development for mapping the extent, type and condition of grasslands, threatening processes and management requirements is needed to reliably map this vegetation type.
Non-forested vegetation
- A focus on mapping forest vegetation has in some cases overlooked non-forest structural formation types that occur within a forest ecosystem (e.g. sedgelands, grasslands, shrublands and open woodlands). This was the case in some of the Comprehensive Regional Assessment data sets that surveyed and mapped only forest structural formation types.
Definition of native and pre-European vegetation
- Varying definitions of present and pre-European native vegetation across States and Territories may lead to misinterpretation of information (e.g. areas in Queensland have been mapped using a restricted threshold for surveying and mapping native vegetation. The Queensland Herbarium uses a definition of vegetation that is 50% of the original pre-clearing foliage cover and 70% of the original pre-clearing height of the upper storey excluding areas that contain modified native vegetation that is mapped by some other agencies).
- Pre-European mapping methods and scale of data collection are different within and between jurisdictions making the interpretation of the type and extent of pre-European vegetation types difficult and analysis compared to present vegetation often impossible.
Avicennia marina, St Kilda Beach, near Adelaide, SA
Photo: Murray Fagg
Riparian/riverine vegetation
- Riparian vegetation and the preservation of the health and condition of riparian zones are crucial factors for long-term sustainability of catchments. Riparian zones, are often the most fertile part of the landscape and are subjected to many pressures from land use change and human activities. Significant clearing of riparian zones over the past 150-200 years in urban and rural environments has led not only to changes in vegetation composition in the land adjacent to rivers and streams, but also to changes in the waterways. Impacts of modifications to riparian areas affect environmental, productivity and quality of life across the community.
- Riparian vegetation is a major focus for on-ground activities by community groups supported by Natural Heritage Trust funding either in managing or rehabilitating these key areas. Accurate descriptions of the extent and condition of vegetation along riverine corridors are essential to quantify the resource, determine trends in the condition of riverine systems, set priorities for on-ground works and determine effectiveness of works and activities.
- Generally requires a finer scale of vegetation mapping for input into management.
- Not specifically incorporated into the National Vegetation Information System.
There is no Australia-wide approach to quantifying the extent and condition of riparian vegetation. The Audit review of riparian data (Sinclair, Knight, Mertz 2000), mapping techniques and knowledge gaps proposes using:
- an Australia-wide coverage using an initial geomorphological classification;
- a scalable data set, using the National Vegetation Information System classification as the basis for further, more detailed data collection;
- use of satellite imagery and aerial photographs for rapid appraisal and to set priorities for any field mapping; and
- although using the National Vegetation Information System classification as the basis, building a data hierarchy that incorporates management-related attributes such as weeds, bank condition and adjacent land use as part of any field mapping program.
An interim riparian mapping product was used by the Audit to assess water-borne erosion and river health (NLWRA in preparation). All streams with a catchment area greater than 50 km² and a length greater than 5 km were mapped across the river basins containing intensive agriculture. The proportion of each stream with cleared native riparian vegetation was determined by comparing stream data with native vegetation derived from Barson et al. (2000). Although at a resolution of 100 m and current to 1995 it is the best available data. It is still only a crude measure of riparian condition as it fails to identify narrow bands of remnant riparian vegetation in cleared areas or narrow valleys of cleared land penetrating otherwise uncleared land.
Wetlands
- Generally require a finer scale of vegetation mapping for input into management.
- Not specifically incorporated into the National Vegetation Information System.
- Range from coastal to riverine to alpine landscapes and are diverse in landscape and habitat types.
- Important for a wide range of uses including biodiversity, primary productivity and the opportunity for recruitment, landscape function and as groundwater sinks.
- Vegetation mapping as well as habitat mapping is important.
Coastal and marine vegetation
- Generally requires a finer scale of vegetation mapping for input into management.
- Not specifically incorporated into the National Vegetation Information System.
- Provide a very diverse range of habitats in potentially sensitive areas where land use impacts can be large.
- Vegetation mapping as well as habitat mapping is important.
- Existing standards need refining and methods need to be developed for mapping the extent, type and condition of these vegetation groups.
Native vegetation condition (changes in vegetation extent, structure and composition)
- Significant progress in assessing native vegetation condition for vegetation management was not possible.
- Knowledge of recent changes and trends in extent of native vegetation would significantly improve our understanding of the impact of clearing on vegetation and landscapes.
- Native vegetation resource management concepts such as condition assessment and monitoring change and trends are not resolved in terms of common definitions and approaches across Australia. A review of the draft condition framework (Environment Australia 2001) based on targeted case studies and testing, a review of requirements for condition information and prioritising requirements would enable the limited resources available for this activity to be better focused.
- Research and development activities focused on priorities for vegetation management to develop methods and bring them into operation.
Weeds
- There is little readily available information on the distribution of weeds at a scale relevant to on-ground management and a lack of association with the native vegetation it may occur in. This would be a key indicator of condition and threat to native vegetation.
Environmental and landscape information
Ecological vegetation communities (defined by associating a range of environmental and landscape attributes to the vegetation types) are unable to be defined across Australia due to a lack of consistent environmental information available at regional scales.
- Data collected on environmental and landscape features (e.g. soils, climate, geology, landforms) of the vegetation are project based or not collected.
- National standards for collecting environmental information (e.g. landforms, geology, soils attributes for vegetation management purposes) do not exist or are not widely supported.
- This information is critical for the ability to adequately represent vegetation types across the range of environments in which they occur, will allow compilation of information about vegetation communities and move towards information and mapping of ecosystems.
Scale of capture in response to management requirements
- Vegetation types under threat or with specific management requirements may require finer scale data collection (e.g. threatened ecological communities, grasslands in urban areas, riparian vegetation). This mapping has not been compiled into Stage I of the National Vegetation Information System.
Irrigated citrus, Griffith, NSW
Photo: Murray-Darling Basin Commission
Site survey
A large amount of information about the vegetation at a site is collected and analysed to develop a vegetation map for an area. Surveyed sites underpin high quality vegetation mapping.
- Data collection and analysis is a fundamental input to high quality and repeatable mapping and monitoring of vegetation types.
- Adoption of the draft site survey collection guidelines (Environment Australia 1999) to complement vegetation attributes will ensure that site information can be linked to vegetation mapping.
Links to land use/catchment/landscape issues
- Will provide integrated inventories of cover and (in context of soils) microclimate and topography.
- Information and knowledge of relationships between native vegetation cover and other land cover types in the landscape is required to assess status of native vegetation. This is particularly important in many rural and urban landscapes where remnant and fragmented vegetation is dominant.
Spatial gaps
Spatial gaps are defined in terms of the geographic coverage and scale of the mapping compiled in Stage I of the National Vegetation Information System.
Humpty Doo, NT
Photo: Murray Fagg
Geographic coverage
Areas where no vegetation data was available to be compiled into the National Vegetation Information System for the present coverage (Figure 41) include western and northern Queensland, north-east New South Wales, small areas in Victoria, northern and western coastal regions of Tasmania, southern Australian Capital Territory and northern South Australia. For the pre-European coverage (Figure 42), no National Vegetation Information System data was compiled in central Queensland and the Wet Tropics, most of New South Wales and the north-western corner of Victoria.
These areas have further been divided between those areas where there is:
- genuinely no vegetation mapping available; and
- work in progress by the States and Territories, including data sets that have yet to be compiled into National Vegetation Information System.
Areas where no vegetation mapping is available in the present coverage occur over most of central South Australia, north-western Victoria, in the area immediately to the north of Melbourne, a small area in central New South Wales, the area to the south of the Gulf of Carpentaria, central western Queensland, and southern Australian Capital Territory. In the pre-European coverage areas where no vegetation mapping is becoming available occur in the north-west of Victoria and areas of the Gulf in north-west Queensland. Small areas of no data also occur in central east Queensland and in the vicinity of Melbourne. Mapping at 1:50 000 is available in some areas of South Australia.c
Many areas have vegetation data sets that were not included in the National Vegetation Information System either because they could not easily be translated and compiled in the available time or they were incomplete. In the present coverage these include most of northern and western Tasmania, south-western Queensland, Einasleigh Uplands and Cape York bioregions of Queensland, coastal areas in the vicinity of Rockhampton, north-east New South Wales and large patches of South Australia. In the pre-European coverage, areas of work in progress include all of the Einasleigh Uplands and Central Mackay Coast bioregions and areas of the Mitchell Grass Downs bioregion in Queensland and most of New South Wales.
Scale
The nominal thresholds specified for the scale of the vegetation data (Table 45, Figure 4) differed in levels of detail for the intensive land use zone and extensive land use zone (Graetz et al. 1995). These thresholds define the scale of the data sets generally required by stakeholders for regional planning and management. Greater detail was required in the intensive land use zone, as it is the area in which human impacts and land use change are greatest and a majority of the decisions relating to natural resource and environment management applies. To meet this requirement finer scale survey and mapping work is required.
| Geography | Present | Pre-European |
|---|---|---|
| Intensive land use zone | 1:100 000 | 1:1 000 000 |
| Extensive land use zone | 1:250 000 | 1:1 000 000 |
Gaps were assessed in terms of the scale of mapping compiled within the National Vegetation Information System data set compared with the scale threshold and included the following conditions:
- where publication scale for a data set was coarser than the threshold (e.g. where the only vegetation data for an area in the intensive land use zone is at 1:250 000 scale this is coarser than the threshold of 1:100 000 scale); and/or
- where no vegetation mapping was available at the requisite scales.
The present vegetation coverage shows that gaps in scale in the intensive land use zone occur where vegetation mapping is coarser than 1:100 000 scale (Figure 43). These occur in the south-west and north-west of Western Australia, the north-west of the Top End of the Northern Territory and most of New South Wales. Gaps in scale in the extensive land use zone occur over most of the Northern Territory and the north-west of New South Wales. In both these cases the vegetation mapping available is 1:1,000,000 scale.
Figure 44 shows the pre-European vegetation coverage relative to the intensive land use zone and extensive land use zone. The pre-clearing coverage in South Australia does not meet the 1:1,000,000 scale threshold.
Currency of vegetation attribute and spatial data
Gaps in the currency of the data were assessed for the present vegetation coverage. The year 1997 was specified as the nominal threshold against which to assess the currency of each vegetation data set and applies equally to attribute and spatial features of the data sets.
Currency of attribute and spatial data was assessed separately as these can be mapped and updated separately and thus are important in understanding data limitations.c
Analysis of gaps in data currency assists in identifying those areas of Australia where the data may be inadequate to support up-to-date regional planning and management. The information should be further interpreted based on the application required (e.g. in areas of rapid change more recent data is required and in areas of little change data older than 1997 is acceptable).
Gaps include the following conditions:
- where field survey work for a data set was completed at least 30 years prior to 1997;
- where a spatial data set was completed at least 30 years prior to 1997; and
- where no vegetation mapping was available.
Currency of vegetation attributes
- Major gaps in the currency of the vegetation attributes relative to 1997 occur throughout Western Australia and in one data set in western South Australia reflecting data where at least some of the attributes were collected in the 1960s. Moderate gaps occur in the south-east of South Australia and the pastoral zone of South Australia, in southern central Queensland and a small area in central Australian Capital Territory. This gap is related to those data sets where at least some of the attributes were collected up to 20 years prior to 1997.
- Minor gaps occur across the Northern Territory, central and eastern South Australia, the majority of New South Wales and the Australian Capital Territory, and the north-west and East Gippsland regions of Victoria.
Currency of spatial boundaries
- Major gaps in the currency of the spatial boundaries relative to 1997 occur in a small area of western South Australia, the pastoral areas of Western Australia and western Australian Capital Territory. These gaps relate to at least some of the line work of these data sets being mapped up to 30 years prior to 1997.
- Moderate gaps occur in the intensive land use zone of Western Australia, most of the Northern Territory and large areas in central and north-eastern South Australia. These gaps relate to at least some of the line work of these data sets being mapped up to 20 years prior to 1997.
- Minor gaps occur in central and south-east South Australia, central and south-east Queensland, most of New South Wales with the exception of the eastern seaboard and adjacent slopes of the Great Dividing Range, the eastern half of the Australian Capital Territory, and north-west and Gippsland regions of Victoria.
Vegetation classification
Yellow Waters, Cooinda, Kakadu National Park, NT
Photo: Murray Fagg
National Vegetation Information System information hierarchy
Six levels of vegetation classification were defined within the National Vegetation Information System information hierarchy (NLWRA 2000a). Level V was specified as the target for compiling native vegetation data into the National Vegetation Information System.
A visual appraisal was conducted of the native vegetation descriptions within the map units of each data set, comparing the Level V descriptions with the requirement for meeting a Level V description. Each data set was allocated one of eight classes of gap where:
- major gaps refer to either no data provided or no useful data being included at Level V; and
- moderate and minor gaps refer to differing degrees of information that is missing relative to the required standard for Level V.
This information is provided as a guide variation occurs in the gaps assigned within a data set. Table 46 shows the type of gap in the level of vegetation detail available relative to the Level V requirements and the relative number of vegetation data sets in each of the gap classes. Table 47 lists the number of data sets and the level of the hierarchy to which they were assigned in the National Vegetation Information System.c
The majority of data sets compiled (66%) have minor or no gaps at level V. Of concern is the 20% of data with moderate to major and major gaps. These data would require further mapping or possibly further effort by custodians to compile information to Level V. Sixty-one percent of present vegetation data and 68% of pre-European data have been mapped to Level V and VI.
| Type of gap | Total number of data sets |
|---|---|
| Major gap | 7 |
| Moderate to major gap | 13 |
| Minor to moderate gap | 15 |
| Minor gap | 2 |
| Nil gap | 67 |
| Number of data sets compliant to Levels | Present | Pre-European |
|---|---|---|
| I - II | 0 | 1 |
| I - III | 19 | 8 |
| I - IV | 6 | 3 |
| I - V | 10 | 8 |
| I - VI | 31 | 17 |
Major classification gaps in the present vegetation data (Figure 45) occur in Western Australia and over most of eastern New South Wales. Moderate gaps occur over western New South Wales and scattered throughout the Australian Capital Territory. Minor gaps occur in Tasmania. No gaps are found in Northern Territory, Queensland, South Australia, Victoria and small areas of the Australian Capital Territory.
Major classification gaps in the pre-European vegetation data (Figure 46) occur in Western Australia and South Australia. Moderate to major gaps occur in the central and south eastern forests data sets in New South Wales. Minor gaps occur in Tasmania. No gaps are found in Northern Territory, Queensland and Victoria.
Consistency in the vegetation classification
Within jurisdictions
Throughout the process of data compilation, checking and validation, the data in the National Vegetation Information System were continually improved.
- A low degree of classification consistency was observed between data sets in the classification of Levels I-III in New South Wales, the Australian Capital Territory and Western Australia.
- A moderate to high degree of classification consistency between data sets for Levels I-III was observed in Tasmania.
- The highest degree of consistency between data sets for Levels I-III were observed in those States and Territories that began the process of developing uniform/unique vegetation descriptions for all their data sets either prior to or during the National Vegetation Information System Stage I project. These include Queensland, Victoria, South Australia and the Northern Territory.
Between jurisdictions
Major classification inconsistencies were observed along the Western Australia and Northern Territory border. Some of these problems appear to be related to differences in assigning a consistent definition of dominance to the upper stratum where Western Australia assigned dominance using the Beard and Webb (1974) method while the Northern Territory assigned dominance using the Walker and Hopkins (1990) method.
At regional to national scales, other less obvious edge matching problems were observed between all jurisdictions.
Resolution of these issues should be achieved if the relevant States and Territories and the Commonwealth agree on a set of rules within the National Vegetation Information System framework to achieve equivalency between the attributes used in the data that meet at borders.
Some of these issues relate to scale and detail of the mapping available, and hence cannot be resolved by seeking equivalency of attributes. The inconsistencies in some instances can only be resolved by additional information and in some cases new survey data will need to be collected. In other instances adjustments will need to be made to the line work of some data sets.c
Reliability of survey and mapping methods
The reliability of survey and mapping methods assists users in determining the applications for which a data set may be used (Figure 47).
Data sets with the lowest reliability (major gaps) included those developed using a combination of minimum and/or limited and/or full site-based surveys. In the present coverage, these occur over most of New South Wales, eastern Australian Capital Territory, and south-east and central Tasmania.
Data sets with moderate reliability (moderate gaps) included those that were developed using a combination of minimum and/or limited and/or full site-based surveys combined with aerial photos and satellite imagery or aerial photos as the interpolation/extrapolation base for mapping. In the present coverage these occur throughout the Northern Territory, patches of New South Wales and a small area in central western South Australia.
Moderate to high reliability (minor gaps) include those data sets that used a combination of limited site-based field survey combined with aerial photos and satellite imagery, or aerial photos as the interpolation/extrapolation base for mapping. In the present coverage these occur scattered through south-east, central and northern South Australia, the central coast of New South Wales, and central and south-eastern Queensland.
Highest reliability (no gaps) included those data sets that used aerial photos or a combination of aerial photos and satellite imagery as the interpolation/extrapolation base for mapping in combination with full site-based surveys. In the present coverage these occur scattered across the Top End of the Northern Territory, scattered patches in central and southern South Australia, two areas in central and south-eastern New South Wales and all data set in Victoria.
In the pre-European vegetation coverage areas of least reliability (major gaps) occur throughout South Australia and Tasmania. Areas of moderate reliability (moderate gaps) occur throughout the Northern Territory. Areas of highest reliability (no gaps) occur in Queensland and Victoria, in south-eastern New South Wales and numerous data sets that are scattered in northern Northern Territory.
Summary of gaps in classification level and scale
Present vegetation
Data sets were ranked relative to the National Vegetation Information System threshold for classification detail (i.e. National Vegetation Information System level V) and scale of mapping of the intensive land use zone (i.e. 1:100 000 scale) and extensive land use zone (i.e. 1:250 000 scale).
In the intensive land use zone (Figure 48):
- Queensland, Victoria and South Australia were ranked above the National Vegetation Information System threshold.
- Small areas in the Northern Territory and Australian Capital Territory were ranked as either equal to or better than the National Vegetation Information System threshold for classification detail and scale of mapping.
- Five of the eight State and Territories (Australian Capital Territory, New South Wales, Northern Territory, Tasmania and Western Australia) had either most or all of their data sets ranked below the National Vegetation Information System benchmark.
In the extensive land use zone (Figure 49):
- Data sets in the Top End of the Northern Territory were ranked as better than the National Vegetation Information System threshold for classification detail and scale of mapping.
- Four of the six States and Territories (New South Wales, Northern Territory, Tasmania and Western Australia) had either most or all of their present datasets ranked below the National Vegetation Information System benchmark.
Pre-European vegetation
Data sets were ranked relative to the National Vegetation Information System threshold for classification detail (i.e. Level V) and scale of mapping the intensive land use zone and extensive land use zone (i.e. 1:1,000,000 scale).
Gaps in the pre-European vegetation (Figure 50):
- Queensland and Victoria were ranked above the National Vegetation Information System threshold.
- Small areas in the Northern Territory were ranked as either equal to or better than the National Vegetation Information System threshold for classification detail and scale of mapping.
- Four of the eight State and Territories (Australian Capital Territory, New South Wales, Northern Territory, Tasmania and Western Australia) had either most or all of their present data sets ranked below the National Vegetation Information System benchmark.
- South Australia was not ranked because the pre-European coverage was compliant with only Level II.
Summary of gaps in the currency of attributes and spatial boundaries
The nominal threshold of 1997 has not been met by most data sets for attributes or spatial boundaries. A comparison between the vegetation attributes and the spatial boundaries shows varying degrees of currency.
The least current vegetation data sets (i.e. major gap-thirty-year old data) are found in the extensive land use zone of the present coverage of Western Australia and a small area of central western South Australia. Moderate (twenty-year old data) to minor (ten-year old data) gaps were observed over much of South Australia and Northern Territory and small areas of Queensland.
This becomes an issue where the native vegetation of a region is known to be undergoing significant change and/or degradation (e.g. through thinning and/or clearing).
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