Four states in the field at Chowilla

The TERN Calperum Mallee Supersite near Chowilla was a hive of activity in late January and early February, when eight AusCover team members from four states descended on the semi-arid site to take field measurements.

AusCover researchers from the University of Adelaide, the University of Queensland, Curtin University and the University of Technology Sydney worked with two people from TERN AusPlots in the 25 square kilometre site in South Australia.

AusCover will use the measurements taken to calibrate and validate the airborne datasets that were captured at the same time, to help build rigorous relationships between the datasets and biophysical vegetation parameters. As the vegetation cover and density at the site is homogenous, the airborne datasets are suitable for scaling to satellite-based continental time-series of biophysical parameters. This will improve the accuracy of maps that cover the whole of Australia. It will make possible the delivery of accurate ecosystem data products designed for Australian conditions, and help scientists model and understand how, in space and over time, some environmental factors have changed during the period for which Australia has satellite images. It will also help decision makers understand accurately the impact of regional environmental management in Australia.

All the datasets from this campaign will be available on the AusCover portal after they have been analysed and the quality assured.

The researchers took these field measurements:

  • Leaf Area Index measurements using the Licor LAI-2200 instrument
  • hemispherical photography
  • star transects observations of vegetation cover at ground level, mid-storey and over-storey as part of the Statewide Land Cover and Trees Study
  • basal area of woody vegetation
  • measurements of vegetation structure (tree height, height to first branch, diameter at breast height, and crown diameter)
  • eaf measurements and samples to identify species;
  • spectrometer measurements of soil types, leaf samples and canopies;
  • spectrometer measurements of ground-calibration targets;
  • sunphotometer and ozonometer measurements to correct atmospheric information in airborne images; and
  • panoramic photo plots, using a similar approach to the one AusPlots uses.

When they were at Chowilla, the team installed two stationary cameras that takes a photo automatically every 10 minutes, to provide data to asses vegetation phenology (the study of periodic events in the life cycles of plants and animals, and how these are influenced by variations in climate). One camera focuses on ground cover; the other, which was installed at the top of the 21 m tall flux tower to take photos of the canopy, will help scientists understand canopy phenology over time.

While the field measurements were being taken, on 1 February Airborne Research Australia captured full waveform LIDAR data and hyper-spectral images for AusCover. A high spatial resolution WorldView-2 satellite image was also captured on the same day.

AusCover scientists collect point-based observations of ground cover,
mid-storey and canopy cover of vegetation at the Chowilla site
Part of the WorldView-2 image of the Chowilla site, showing
grey and black ground-calibration targets that are 64 square
metres each. The targets are used to ensure the final images
have the correct reflectance.

Published in TERN e-Newsletter February 2012

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