How Integrated Land Resource Surveys are Conducted
Land system and land unit mapping are integrated land resource surveys, describing the landscape from more then one perspective. The definition of both a land system and land unit incorporates a landform, soil and vegetation component.
Priorities for survey areas are determined in response to land use demand. Factors considered include agricultural development, integrated catchment management and land use planning for an ever broadening range of land use demands. In the last 10yrs land resource mapping has provided planners with the information they need to manage the landscape in the Greater Darwin Region, allowing for rural living, horticultural expansion as well as protecting important ecosystems such as wetland and riparian habitats.
Land resource officers determine a survey area from catchment boundaries, local government boundaries or land use demands. A survey team usually consists of a pedologist (soil surveyor) and botanists. Upon determining a study area remote sensing products are acquired, commonly aerial photography and satellite imagery. All available information such as geological, topographical and cadastral maps, are acquired to better understand the biophysical resources and land use demands. Preliminary land unit or map unit boundaries are determined from this information.
A field program is then undertaken to describe the biophysical properties of map units. Survey sites, which can total in the hundreds, are described to national standards with particular reference to landform, soil and vegetation. Landform information collected includes slope, rock and gravel. Soil descriptions include depth, colour sand and clay, substrate, pH, structure and gravel. Vegetation descriptions are described from a plot and include descriptions of structure, strata, species and canopy cover.
When all land types have been described the data is entered into a soil and vegetation database. Sites are analysed and those that contain similar landscape features are grouped into a map unit and described as such. Maps are generated using a geographic information system. Further interpretations of map unit descriptions can produce additional maps such as erosion risk, soil drainage conditions, habitat value, and agricultural land capability.
Land resources are described and mapped in accordance with the standard practices applicable at the time the survey was conducted. These standard practices are often based upon published references which are found in the survey reports and/or metadata.
LRM land resource information is collected, analysed and described according to nationally agreed standards. These standards are contained within a number of publications most of which are available through the Australian Collaborative Landscape Evaluation Program (ACLEP).
These publications include:
- Australian Soil and Land Survey Field Handbook - Third Edition
- Guidelines for Surveying Soil and Land Resources - Second Edition
- The Australian Soil Classification - Revised Edition
- Soil Physical Measurement and Interpretation for Land Evaluation
Vegetation information is collected and described in accordance with the “Northern Territory Guidelines and Field Methodology for Vegetation and Survey” (2007).
How Integrated Land Resource information is Used
Land resource mapping is used daily as a decision support tool, for subdivision proposals, agricultural developments, monitoring programs and conservation projects. Listed below are some common uses across the NT:
- Property Management Planning
- Erosion and Sediment Control Planning
- Horticultural Development
- Protection of Sensitive Habitats
- Planning Rural Living
- Assessment of Development Proposals (subdivisions and clearing applications)
- Pastoral Land Management
- Bushfire prediction and intensity
- Land Monitoring
- Property Valuation