Consistency of the presentation of forests on topographic maps

Abstract

This article analyses the accuracy of the presentation of forests on Polish topographic maps. Four test polygons were selected, differing in forest coverage and spatial distribution of forest areas in order to improve the objectivity of the study. All the polygons were located in Roztocze. Four maps were tested: System 1965 (1:50 000), GUGIK80 (1:100 000), PUWG92 (1:10 000), and VMap L2 (1:50 000). The forest areas from the maps and aerial photographs were vectorised; then the photographs were converted into an orthophotomap that constituted the reference material. All materials were coherent in terms of content validity. After vectorising the range of the forests, sampling was conducted within the hexagonal fields. A comparison of the obtained values provided the basis for maps that presented the errors. The analysis permitted several conclusions to be drawn, generally stating that the credibility of maps within the scope of presenting forest areas depends on the scale and purpose of the map, and that any analyses based on these maps should assume that the results should have higher tolerance levels.

Keywords

• topographic maps
• change in forest coverage
• forests
• roztocze