Use of satellite images in forestry

State forest account is one of the main tasks of state forestry. Such account is used when arranging forestry activities, converting forest lands into nonforest lands, registering rights to forest rent plots. In all these cases information users insist on submitting most recent data about the forest lands, whereas formerly forest inventory in Russia was executed once in 10-20 years (now this interval becomes even bigger in many regions). In current situation the most efficient way to update forests condition is by taking satellite images.

The core advantages of space images, as compared to traditional aerial photography:

• Quick access to the near real-time data within a few days (or even hours). Such on-line operation is required, in particular, when executing timely direct control of forest pest outbreak areas;
• Availability of images for different dates over the period of several years ensured by the automatic continuous satellite images downlink and storage in database. Most important for interpretation are winter, summer and spring color images of the same forest area;
• Availability of images with different scales and spatial resolutions in digital format, gridded and processed to standard map projection. Such characteristics allow for quick “attachment” of images to forest GIS and data bases;
• Possibility of acquiring free low resolution general images and low prices for high resolution images at the scales down to 1:25 000.

Recently, satellite images market has good signs of decrease in prices, open access to the images of medium and high resolution directly from several satellites, whereas high prices of air survey urged forest inventory to order 1:40 000 images (even 1:60 000) instead of the required 1:10 000 scale images.

The acting Russian Instruction on Forest Inventory (1994) provides for the use of space images in decision-making within a wide range of tasks, especially when managing intact frontier forests of northern and eastern regions of Russia. For the past 10 years both surveying equipment technology and interpretation capabilities in automatic and semi-automatic mode had a dramatic increase. All this enables to efficiently use satellite imagery data, including continuous forestry inventory with annual updating of the state forest account data.

The best effect of the space imagery is produced while solving the following problems:

• Forest acreage determination and spatial distribution of forests;
• Tree species composition;
• Mature and overmature forest discrimination;
• Forest regeneration control of felled, burnt and windthrow areas;
• Forest field shelter belts control in southern regions;
• Monitoring of died-back areas during pests control.