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Product pages » Fractional cover - Field sites data

Fractional cover - Field sites data

Last modified by Rebecca Mcphee on 2013/07/09 14:41

Managed by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)

Link to the data

Overview

The ground cover reference sites data include site descriptions and field measurements of fractional cover at sites across Australia. These data have been collected by state and territory government agricultural agencies as part of the ‘Ground cover monitoring for Australia’ project.

This field site database contains 464 observations from 461 unique sites across Australia collected between 2010 and 2013. The data is being used to calibrate, validate and improve vegetation fractional cover products derived from remote sensing, in particular the satellite sensors MODIS and Landsat. The data is being used to improve the national MODIS-derived product of Guerschman et al. (2009).

The non-woody vegetation and litter covering the soil surface are referred to as ‘ground cover’. Fractional cover data derived from remote sensing can be used to monitor ground cover and to identify areas at risk of soil erosion. The ‘Ground cover monitoring for Australia’ project is delivering estimates of Australian ground cover at 500 metre resolution from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. 

Map 1 Locations of published field sites with observations of fractional cover

Map 1 Locations of published field sites with observations of fractional cover 

Source: ABARES 2013, Australia ground cover reference sites database

Key specifications
Spatial resolutionEach field site is 1 hectare (100 x 100 metres) in size
Spatial coverageAreas of agricultural land use in Australia
Temporal resolutionTime and date of field data collection is specified. Data collection occurred within 3 hours of the time specified. Where no time is provided the temporal resolution is only available to the day.
Temporal coverageJuly 2010 - February 2013
CustodianThe Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) is the custodian of this dataset.

These data have been collected by the: New South Wales Office of Environment and Heritage, Department of Premier and Cabinet; Northern Territory Department of Land Resource Management; Queensland Department of Science, Information Technology, Innovation and the Arts; South Australia Department of Environment, Water and Natural Resources; Tasmania Department of Primary Industries, Parks, Water and Environment; Victoria Department of Environment and Primary Industries; and the Western Australia Department of Agriculture and Food.
VersionJune 2013
Field methodMuir, J, Schmidt, M, Tindall, D, Trevithick, R, Scarth, P and Stewart, JB 2011, Field measurement of fractional ground cover: A technical handbook supporting ground cover monitoring in Australia, prepared by the Queensland Department of Science, Information Technology, Innovation and the Arts for the Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, available at http://adl.brs.gov.au/data/warehouse/pe_hbgcm9abll07701/HndbkGrndCovMontring2011_1.0.0_HR.pdf (PDF, 81.20MB).
Datasets
Product nameSpatial resolutionTemporal resolutionLink to dataset
Ground cover reference sites database100m x 100m field sites nationally for AustraliaJuly 2010 - February 2013Database
Future development

The database may be updated if more observations are submitted to ABARES for processing or errors are reported.

Background

At a national workshop in November 2009 the MODIS-derived vegetation cover product of Guerschman et al. (2009) was selected for monitoring ground cover for Australia (Stewart et al. 2011). The workshop also identified the need for a national network of ground cover reference sites to calibrate, validate and improve the accuracy of ground cover estimates. To store and retrieve field measurements of fractional cover, site descriptions, site images and other associated data, a database was required. This database was created based on the recommendations of the 2009 workshop and modified through discussions with field data providers, jurisdictions and the data received.

Methods

Data collection by state and territory agencies commenced in July 2010 and continued until February 2013. The ground cover reference sites database conforms to the methods described in Muir et al. (2011). Choice of site locations was informed by a sampling strategy (Malthus et al. 2013) and sampling protocols (Stewart et al. 2012; Stewart et al. in prep.). Sites were to be located in areas dominated by non-woody vegetation with tree canopy cover less than 20 per cent under grazing or broadacre cropping land uses. The sampling strategy excluded areas with tree cover greater than 20 per cent (based on Montreal Process Implementation Group for Australia 2008), and non-agricultural land uses such as urban, conservation or indigenous land uses (based on ABARES 2011). Due to site and imagery access limitations some observations were collected in areas of land uses classed as national parks, nature conservation and traditional indigenous uses. The majority of sites are located in the rangelands.

Quality

Quality and limitations

The field data is intended to reflect the conditions in the field at the time of data collection in a consistent format. Data users should consider that there is a level of subjectivity in the observations which may vary between field operators and locations. Training sites are less reliable and incomplete compared to data collected once field operators became proficient in the transect and site description methods. Local conditions, operator experience, and equipment (such as GPS accuracy) all influence the observations. Most observations were taken visually and subsequent validation of species identity, biomass estimates and other attributes were not required. 

Data completeness

The database contains 464 field site observations from 461 unique sites from the ‘Ground cover monitoring for Australia’ project that have permission to be published as at April 2013. A total of 545 observations were collected under the ‘Ground cover monitoring for Australia’ project. Some project partners requested that field observations on private land not be published due to privacy concerns. The total number of observations collected by each state is shown in Table 1. The locations of the publishable sites in the database are shown in Map 1. 

Table 1 Number of observations in each state

StateTotal observations Published observations Unpublished observations 
 New South Wales 91 58 33
 Northern Territory 109 95 14
 Queensland 30 28 2
 South Australia 100 88 12
 Tasmania 25 25 -
 Victoria 48 28 20
 Western Australia 142 142 -
 Total545 464 81

Note: Data from unpublished sites may be acquired for specific research projects at the discretion of the relevant state agency.  

Validation

Data have been checked for consistency by ABARES. The quality of the database is dependent on the quality of field data collected by field operators as described in Muir et al. (2011).

Other specifications

CitationABARES (2013) Australian ground cover reference sites database. Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, Australia.
Data sourceData has been collected under the ‘Ground cover monitoring for Australia’ project to establish a national network of ground cover reference sites. The ground cover reference sites database conforms to the national standards for the field measurement of fractional ground cover and the description of sites (Muir et al. 2011). The data collected is entered into two electronic Microsoft Excel spreadsheets — the site description form and the transect form — and along with digital site photographs provided to ABARES for inclusion in the ground cover reference sites database. In developing the database, data users requested that it be created using open source software and have the ability to display site data within a geographical information system (GIS). PostGIS was chosen as it enables the object-relational database PostgreSQL to serve the site data spatially by site location, and to query the data using SQL (Structured Query Language) functions.
Geographical coverageThe data has been collected nationally for Australia. The data has the following spatial extent (coordinates of the cell outer edge):
Lower left = 110.000000, -45.000512
Upper right = 155.001329, -10.000000
Number of columns = 9580
Number of rows = 7451
Coordinate systemData are provided as points with latitude and longitude unprojected, in geographic decimal degrees, referenced to the coordinate system WGS84.
Positional accuracyEach field site is 1 hectare (100 x 100 metres) in size. The sites are chosen to be representative of the surrounding area to a MODIS pixel size of 500 x 500 metres, and to have been visited as close as possible to cloud free Landsat imagery collection.  Standard GPS (not differential GPS) have been used to locate the centre point of the field site resulting in an estimated positional accuracy of approximately 25m depending on the device used.
AccuracyThe quality of the database is dependent on the quality of field data collected as described in Muir et al. (2011). Training sites may be less reliable and incomplete compared to data collected once field operators are proficient in the transect and site description methods.
CompletenessThe database contains field site observations from the ‘Ground cover monitoring for Australia’ project that have permission to be published as at April 2013.
Update planThe data were collected between July 2010 and February 2013. The database may be updated if more observations are submitted to ABARES for processing or errors are reported.
Data licenseThese data are made available under the conditions of the Creative Commons Attribution-ShareAlike 3.0 License:
http://creativecommons.org/licenses/by-sa/3.0/ Data can be copied, distributed and adapted provided that relevant products are attributed to ABARES. Any derived products should be distributed under the same or similar license.
Use constraintsIn return for free access to these data, citations and copies of publications arising from work using these data should be sent to land_management@daff.gov.au.   
The ground cover reference sites database is provided ‘as is’ without guarantee or warranty of any kind, either expressed or implied, including without limitation, any warranty of merchantability or fitness for a specific purpose. Commercial decisions should not be made without more detailed studies. ABARES may at any time, at its discretion, amend, vary or modify these terms and conditions. Modifications to these terms and conditions will be effective immediately and any subsequent use of the database will constitute acceptance of the modifications.
ContactDepartment of Agriculture Fisheries and Forestry, Australian Bureau of Agricultural and Resource Economics and Sciences
GPO Box 1563
Canberra ACT 2601
Phone: +61 2 6272 2010
Fax: +61 2 6272 2001
Email: land_management@daff.gov.au
Web: http://www.daff.gov.au/abares

References

Documentation

Field database user guide
Rickards, JE, Stewart, JB, McPhee, RK, & Randall, LA 2013, Australian ground cover reference sites database: User guide for PostGIS, Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, available at https://remote-sensing.nci.org.au/u39/public/html/modis/fractionalcover-sitedata-abares

Handbook of field methods
Muir, J, Schmidt, M, Tindall, D, Trevithick, R, Scarth, P and Stewart, JB 2011, Field measurement of fractional ground cover: A technical handbook supporting ground cover monitoring in Australia, prepared by the Queensland Department of Science, Information Technology, Innovation and the Arts for the Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, available at http://adl.brs.gov.au/data/warehouse/pe_hbgcm9abll07701/HndbkGrndCovMontring2011_1.0.0_HR.pdf (PDF, 81.20MB)

Ground cover monitoring for Australia: http://www.daff.gov.au/abares/aclump/land-cover/ground-cover-monitoring-for-australia 

ABARES (2013) Australian ground cover reference sites database. Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra, Australia. https://remote-sensing.nci.org.au/u39/public/html/modis/fractionalcover-sitedata-abares

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