Current issue: 57(2)
Under compilation: 57(3)
The purpose of this study was to test the benefits of a forest site quality map, when applying satellite image-based forest inventory. By combining field sample plot data from national forest inventories with satellite imagery and forest site quality data, it is possible to estimate forest stand characteristics with higher accuracy for smaller areas. The reliability of the estimates was evaluated using the data from a stand-wise survey for area sizes ranging from 0.06 ha to 300 ha. When the mean volume was estimated, a relative error of 14 per cent was obtained for areas of 50 ha; for areas of 30 ha the corresponding figure was below 20 per cent. The relative gain in interpretation accuracy, when including the forest site quality information, ranged between 1 and 6 per cent. The advantage increased according to the size of the target area. The forest site quality map had the effect of decreasing the relative error in Norway spruce (Picea abies) volume estimations, but it did not contribute to Scots pine (Pinus sylvestris) volume estimation procedure.
After the Second World War Finnish Forest Service was faced with large e-mapping and timber surveying project in Northern Finland. The funds for mapping were very limited. In order to re-map the large areas, the only way was to look for alternative methods for the ground methods. The photogrammetric equipment of Finnish Army was made available to the civil service. Consequently, since 1947 several forest mapping projects were carried out in co-operation between the Forest Service and the Army Topographic Service.
When more funds were coming available for the project, new instruments were acquired. The article describes the present mapping procedure and suggests alternative ways in procedure and utilization of new equipment. It concludes that if the forest area under modern timber management plans is several million acres, the ideal implemental framework for mapping and timber surveying unit in Finland should be the following: Radial Secator RS I and slotted templates for the radial line plot, Stereotope Plotter for drafting general maps, the old Delft Scanning Stereoscope for photo interpretation, and Aero-Sketchmaster for transport of the photo details.