Vegetation Mapping Extension Study

Challenge

The effect of urban expansion on the natural environment has the potential to significantly impact the conservation of significant vegetation communities. Particular types of vegetation, both remnant and non-remnant, have specific relevance to conservation planning and bush fire hazard management. Accurate vegetation mapping is of considerable importance in minimising a range of potential impacts on vegetation communities and providing adequate decision support for management and conservation planning in the midst of urban expansion and development.

Recognising this, Toowoomba Regional Council (TRC) initiated a program to increase the accuracy of vegetation mapping in order to maximise positive economic, environmental and social outcomes for the state and region. GHD was commissioned to conduct fieldwork and to produce vegetation mapping of increased accuracy to inform ongoing planning efforts.

How we achieved the objectives

A systematic and transparent methodology was applied to map vegetation extent and type. The process involved a combination of site sampling stratification, field survey, remote sensing, aerial photography interpretation, geospatial interpolation and modelling. The methodology developed was designed to provide a rigorous yet practical approach within the limitations imposed by the immense size of the study area coupled with the improved level of mapping detail required and time constraints.

Field survey data was statistically analysed and qualitatively assessed to define vegetation community types for surveyed locations which were then attributed to the vegetation extent defined by remote sensing processes. The utilisation of GIS enabled the process to take a balanced, transparent and traceable approach that considered the spatial relationships of the vegetation extent to field surveys and regional ecosystems data provided by DERM.

Scope

The vegetation mapping was undertaken in a number of stages, including:

• Gap analysis (existing data compilation and analysis)
• Vegetation sampling strategy (field site stratification and identification)
• Remote sensing analysis (algorithm development and image processing)
• Field survey (field data collection)
• Aerial photography interpretation (refinement of vegetation extent, interpretation to expand field survey results)
• Data integration (integration of field survey data, spatial interpolation to assign type, standardisation of attribution)
• Data quality review (review of results, calculation of summary statistics)
• Project output preparation (delivery of digital data, methodology reporting)

Benefits

This mapping represents the first of its kind in the region and is now being used to plan for the protection and management of vegetation through statutory and non-statutory mechanisms.