Methodology
Guidelines and field methods (pdf 2.5Mb) for vegetation survey and mapping have recently been developed for the NT to be consistent with national standards.
The Australian Soil and Land Survey Handbook has recently been revised and incorporates vegetation chapters from:
- Field Handbook (Yellow Book - Vegetation Chapter) Roger Hnatiuk, Richard Thackway and Joe Walker (Editors).
- Guidelines for Conducting Surveys (Blue Book - Vegetation Chapter) Richard Thackway, John Neldner and Matt Bolton (Editors).
A series of steps are involved in vegetation survey and mapping. Briefly these include:
Step 1 - Survey Design and Planning
The following aspects are considered:
- Survey purpose (i.e. target population, geographic extent & mapping type).
- Mapping scale (set by imagery used i.e. aerial photography or satellite imagery).
- Available resources (staff, funds, equipment, vehicles).
- Information search for ancillary data.
- Survey design.
- Proposed classification system to be used to combine both structural and floristic vegetation characteristics (e.g. Specht 1970, Beard & Webb 1974, Walker & Hopkins 1990).
Step 2 – Production of a Preliminary Map
Patterns of vegetation are perceived on interpretative materials (aerial photography, satellite imagery etc.) are used to produce an initial map. This map is coded with preliminary UMA’s which are then verified in the field.
Step 3 – Collection of Vegetation Attributes in the Field
The Land and Vegetation Unit use a physiognomic-floristic approach to vegetation survey and classification based on a standard methodology and quadrat size. A combination of physiognomy, floristic composition, and vegetation profile information is essential to identify and describe plant communities. In addition, environmental and physical parameters are collected. Two site sheets are used to record this information – Habitat Sheet (pdf 56Kb) includes survey details, location and geo-referencing, soils, disturbance, landform and ground cover; the Flora Sheet (pdf 278Kb) and vegetation foliage projective cover sheet (pdf 36Kb) include species occurrence (full or broad floristics), crown cover/foliage projective cover, height, strata, growth form and basal area.
Step 4 – Data Analysis to Define and Map Vegetation Types/Communities
The primary function of analysis is to summarise site based vegetation attributes to generate a vegetation description (i.e. Eucalyptus miniata, E. tetrodonta and Erythrophleum chlorostachys woodland with annual Sorghum sp., Heteropogon triticeus and Chrysopogon latifolius tussock grassland. The process involves:
- Classifying site data using multivariate analysis software (i.e. PATN, TWINSPAN) to produce site groups/assemblages based species, structural components and environmental data.
- Relate site groupings back to the mapping (attributing).
- Undertake an assessment of attribute and spatial accuracy prior to releasing final outputs.
Step 5 – Final Map and Report
The final output is the vegetation map with accompanying detailed technical report. In some cases interpretive maps are created (i.e. landform, drainage, soils etc.).
Metadata is provided including a structured description and summary of the dataset (data content, currency, access, availability & quality) including links to ANZLIC metadata attributes.
