Ground Cover Report

What is a ground cover report?


The Ground Cover report shows a ground cover and minimum ground cover map for the selected Lot or Lots on Plan generated from satellite imagery. The ground cover map displayed is for the season and the year selected. The minimum ground cover map indicates the lowest ground cover for each satellite pixel in the selected Lot (or Lots) on Plan since the early 1980s. The report also shows a time series graph (1988 to the present) of percentage ground cover values derived from two sources: pasture modelling and satellite imagery.

 

What is a ground cover - regional comparison report?


The Ground Cover - Regional Comparison report shows the ground cover levels over time for the dominant land types for the selected Lot (or Lots) on Plan. Property ground cover levels are compared to the ground cover levels over time for the same land types on similar land tenures in the local region, defined by a 25km or 50km radius around the selected area depending on the size of the area.

 

What is included in the ground cover report?


There are two ground cover reports available on FORAGE:

  • Ground Cover
  • Ground Cover – Regional Comparison

 

Report sample


Report sample is available online here (PDF, 241.1 KB).

Report sample (regional comparison) is available online here (PDF, 3.3 MB).

 

Common questions about ground cover reports


For a selected Lot on Plan or adjoining Lots on Plan in Queensland, the Ground Cover – Regional Comparison report:

  • Presents the seasonal ground cover levels for each of the dominant GLM land types for the selected Lot(s) on Plan.

  • Compares ground cover levels for these land types on the selected Lot(s) on Plan, with the same land types in the local region (within 25 to 50 km radius depending on the size of the Lot on Plan) from year 2000 to the present. This comparison can be made either as:

    • A ranking (percentile) against the region.
    • Actual percentage cover levels for both the land type on the Lot(s) on Plan and the same land type in the surrounding region.
  • For more details, see Pages 7 and 8 of the FORAGE User Guide (PDF, 2.8 MB) .

  • Provides a check on ground cover levels against the surrounding region.

  • This check may help to identify land types which may be subject to high or low grazing pressure when compared to the district average.

  • This report will simply raise questions which, upon further evaluation, may or may not lead to a grazier re-evaluating their management of a particular land type.

  • Graziers do not base their management on what is happening in their surrounding district. However, it may be useful for graziers to see that ground cover levels on their Lot(s) on Plan are higher than in the surrounding district. Conversely, it may serve as a warning if ground cover levels on their Lot(s) on Plan are lower than in the surrounding district.

  • The Ground Cover – Regional Comparison report uses what is known as ‘fractional’ ground cover.

  • An algorithm is applied to the Landsat satellite imagery which classifies the ground cover into the green and non-green cover components (or ‘fractions’), and bare ground.

  • As both green and non-green fractions are summed to obtain total cover, the ground cover levels reported may therefore include high litter or non-green fractions which are useful for protection of the soil against erosion, but may not offer useful nutrition content to livestock. Likewise, the green fraction may have a high proportion of undesirable pasture species or weeds.

  • The satellite imagery does not distinguish between pasture composition, biomass or feed on offer.

  • Seasonal ground cover data is derived by compositing imagery acquired over a season to produce an image that is representative of the median levels of cover measured throughout the season.

  • The ground cover value reported is an actual value selected as being the median of the range of measured values.

The calculation excludes areas identified, based on Queensland Land Use Mapping Program ( https://www.qld.gov.au/environment/land/vegetation/mapping/qlump/) data, as non-grazed areas such as national parks. Travelling stock routes are also excluded from the calculation.

  • High tree cover areas (>45% FPC) are excluded from the calculation due to difficulties of assessing ground cover in such areas.

  • The selected Lot(s) on Plan is also excluded from the calculation of the regional percentiles.

  • The use of a localised radius is intended to reduce the influence of climate variability on any comparisons as it assumes the local region will have experienced similar rainfall and climate.

  • A 25-50 km radius is considered ‘local enough’ to reduce regional rainfall effects, but broad enough to include a large enough region to make a meaningful ground cover comparison.

Last updated: 13 November 2017