Specials Environment

Updated May 1999

Special: Remote Sensing for Decision-makers

Forest decline assessment and monitoring

Pilot study in Poland

Introduction | Aquaculture | Forest management | Rangeland assessment | Groundwater exploration | Forest fire management | Forest decline assessment | Crop information systems | Inventory and monitoring of shrimp farms


Landsat TM image superimposed on three-dimensional view of the Sudety Mountains. Broad deforestation is seen at high elevations

Air pollution from industrial activities resulting in acid rain and deforestation is the main cause of damage to forests. The forests of the Sudety (Poland and Czech Republic), Erzgebirge/Sumava (Germany/Czech Republic) and Harz (Germany) mountain ranges are considered to be the most heavily damaged in Europe. Furthermore, the rapid development of forest decline damage in the western portion of the Sudety Mountains has been described as an ecological disaster. These mountains are located in the "black triangle" of Europe - a heavily polluted region where the use of satellite data is essential as large areas need to be studied by a reliable and repetitive source of information on environmental conditions.

A case-study in Poland: mapping forest decline in the Sudety Mountains

On the basis of Landsat TM satellite data interpretation, the following classes of forest damage were distinguished: impaired spruce stands, severely impaired spruce stands, dying and dead stands, afforestations, old and new clear cuts (deforestation) and mixed and deciduous forest stands. The spatial distribution and area of each class permitted conclusions to be made concerning the state of the forests, the extent of the regions with different degrees of damage and the assessment of the loss of increment in timber volume. Superimposing the satellite image on the digital terrain model also permitted an analysis of the distribution of damage versus elevation above sea level, slopes and other features.

Monitoring and analysis of change over time of forest decline damage

The use of multitemporal Landsat TM images taken in 1984,1990 and 1994 permits the analysis of changes over time in the state of the forests. The spatial extent and the occurrence of the forest decline phenomenon in the Sudety Mountains are shown to be dramatic. Since the end of 1970s there has been a heavy loss of forest in this area which is still continuing. Satellite data show that forest decline is observed throughout the whole area under study and that decline processes are still developing, even though the activities of the Forest Service seem to be more efficient in fighting this deterioration than in the first half of the 1980s. During the last few years, in the region studied there has been a decrease in the area covered by damaged and dying stands as a result of timber cutting and an increase in the surface covered by young and mixed stands as well as a decrease in the bare, open areas as a result of reforestation.

Digital forest maps integrated with descriptive databases form forestry-oriented Geographic Information Systems, which help in the interpretation of the satellite images

Map of the state of forests in the Sudety Mountains (original scale 1:25,000) showing the dramatic extent of damage to the forests. Red colouring represents dead and dying forests; yellow, deforestation caused by declining processes; and different shades of green, spruce stands in varied conditions

Evaluation and recommendations

Costs and delivery times

 Costs (US$/km2)Time (months)
Acquisition of satellite data1.21.0
Digital processing0.30.5
Thematic interpretation0.50.5
Ground survey0.40.5
Map preparation0.60.5

A cost-effective technique

The use of satellite imagery has provided up-to-date maps of the state of the forests which helps in assessing and monitoring the state of the environment in heavily polluted regions. An inventory of a large area, based on satellite information, permits rapid and repetitive evaluation of different aspects of the condition of forests.


The methodology used for mapping forest decline is especially useful in mountainous regions, where accessibility makes frequent field investigations problematic. Furthermore, the synoptic view provided by satellite data permits the study of the area as a whole.

The study was conducted at the OPOLIS-Remote Sensing and Spatial Information Centre of the Institute of Geodesy and Cartography in Warsaw (Poland) with the support of UNEP-Geneva.

Adapted from FAO Remote Sensing for Decision-makers Series, No. 13, "Satellite imagery for forest decline assessment and monitoring". For a full list of issues available in the Series, see FAO Publications on Remote Sensing

The designations employed and the presentation of material in this brochure do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authority, or concerning the delimitation of its frontiers or boundaries.

Remote sensing Introduction | Aquaculture | Forest management | Rangeland assessment | Groundwater exploration | Forest fire management | Forest decline assessment | Crop information systems | Inventory and monitoring of shrimp farms

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