The Remote Sensing Survey
As part of the Global Forest Resources Assessment 2010 (FRA 2010), FAO and its member countries and partners will undertake a global remote sensing survey of forests. This survey is aimed at substantially improving the knowledge on land use change dynamics over time, including deforestation, afforestation and natural expansion of forests. Building on the large existing network of national correspondents and other contacts and using a participatory process, the capacities of developing countries to determine historical rates of deforestation and to monitor current and future rates using a common framework and agreed methodology will be considerably strengthened.
A brochure on the FRA Remote Sensing Survey has been prepared and is available at the FRA Website at: www.fao.org/forestry/media/16692/1/0/.
The FRA 2010 Remote Sensing Survey builds on the experiences from the remote sensing surveys of the tropical region undertaken as part of previous global forest resources assessments and on recent advances in methodologies and availability of imagery.
The survey will primarily be based on the use of available Landsat imagery, but will incorporate auxiliary information including other remote sensing images, local knowledge and results from existing and past field inventories. A systematic sampling design will be used based on each longitude and latitude intersects as illustrated below, with a reduced intensity above 60 degrees North due to the curvature of the Earth.The assessment will cover the whole land surface of the Earth and will consist of about 13,500 samples, of which about 9,000 samples are outside deserts and areas with permanent ice. The area covered at each sample site is 10 km x 10 km, providing a sampling intensity of about 1 percent of the global land surface. This grid of sample plots is the same as used for the national forest assessments supported by FAO and by many national forest inventory programmes.
For each sample plot, four Landsat images - dating from around 1975, 1990, 2000 and 2005 -will be interpreted and classified and a change matrix prepared providing quantitative information on the magnitude of different land use change processes. FAO and its partner organizations will make rectified and pre-processed imagery available through an on-line information gateway and will develop the necessary training material. The testing and development of different tools to aid the interpretation process are currently underway.This initiative is expected to form a pilot for the establishment or strengthening of national remote sensing based monitoring systems in many developing countries.
Key outputs and outcomes of the FRA 2010 Remote Sensing Survey will be:
- Improved knowledge on global forest and land use changes, especially patterns and processes of deforestation, afforestation and natural expansion of forests;
- Baseline information at the global, biome and regional level on trends in the rate of deforestation over the past 30 years;
- A global framework and commonly agreed methodology for monitoring forest change, which can easily be replicated and expanded to generate statistically valid estimates at country level;
An information gateway providing easy access to remote sensing imagery, which can also be used for other studies and monitoring purposes; - Enhanced capacity in all countries for monitoring, assessing and reporting on forests and land use changes.
Although the focus of the survey is to generate information at regional and biome levels, it will be possible for larger countries to derive statistically valid estimates of past and current deforestation rates at the national level as part of this survey should they so wish. For smaller countries, the costs of providing additional pre-processed imagery to enable the generation of statistically valid national level estimates will be marginal. A process to meet such demands will be in place in 2008. FAO also provides technical support for national forest assessments and the establishment of national forest monitoring systems upon request.
The expected duration of the FRA 2010 Remote Sensing Survey is 4 years starting mid 2007.
Additional details of the approach are described in the FAO working paper "Global Forest Resources Assessment 2010: Options and recommendations for a global remote sensing survey of forests", also available at: www.fao.org/forestry/fra.
For more information on the location of images, see the FRA RSS Partners webpage.
For further information, please contact: fra@fao.org