journal of forest science

JOURNAL O OREST SCIENCE, 47, 2001 (7): 307–313
A spatially explicit decision support system for locating forest
roads
E. PACOLA 1 , J. TUÈEK 2
1Technical University, Faculty of Forestry, Department of Forest Exploitation and Mechanization, Zvolen,
Slovak Republic
2Technical University, Faculty of Forestry, Department of Forest Management and Geodesy, Zvolen,
Slovak Republic
ABSTRACT: The paper presents theoretical elements of cartographic modelling of skyline yarding distances, and their
implementation in a raster digital elevation model (DEM) within the ArcInfo TM environment. Modules for yarding distances
are programmed in the Arc Macro Language (AML). The concept of Spatial Decision Support System (SDSS) for laying
out forest roads with concern to terrain and technological criteria is also presented. The most important data source for
SDSS is a cartographic model of skyline yarding distances. Powerful tools of map algebra programmed in AML with implementation
of fuzzy logic are used in data processing.
Keywords: skyline yarding distances; digital terrain model; ArcInfo TM ; spatial decision support system; fuzzy logic
Typical forest areas in Slovakia have fairly extensive
road network density (in some areas over 100 m/ha).
However, the road class and the spacing of existing forest
roads are very unfavourable. or example the ratio
between main forest roads (asphalt surfaced) and other
roads is 1:3 to 1:5. Another problem is the predominance
of tractor skidding technologies. Tractor skidding has
recently spread to mountainous terrain conditions (45%
of the territory of Slovakia). In such conditions it is preferable
to use skyline yarding technologies since, from an
ecological perspective, it is essential to restrict the density
of ground skidding trails.
Thus the primary issue concerning the siting of forest
roads in Slovakia is not to develop a road network in
previously unaccessible areas. On the contrary, transport
planning in these conditions is focused on: (1) the placement
of new hauling roads into the existing forest road
network where areas are not fully opened up, (2) the reconstruction
of selected skidding trails and some hauling
roads (not asphalt surfaced) to main hauling roads and
(3) the rehabilitation of skidding trails which are not
worth rebuilding and using skyline technologies. The
forest road planning manager in these cases focuses on
judging the efficiency of the existing forest network. One
of the basic criteria for this judgment is skidding and
yarding distance.
In previous studies (TUÈEK, PACOLA 1999) we concentrated
on the evaluation of skidding and yarding dis-
tances using DEM. The proposed distance models linked
with IDRISI geographic information system were not
fully optimized models for opening up of a forest. The
program lacked the means to rapidly develop and evaluate
route location based on the digital elevation model.
In the present study we have focused on removing
model limitation described in TUÈEK and PACOLA
(1999) and designing future SDSS for laying out forest
hauling roads with respect to technological criteria as
skyline yarding distance. At the same time, we have developed
the theory of building a cartographic yarding
distance model according to that described in TOMLIN
(1990).
METHOD
The modules described here were created for the
ESRI’S UNIX based ArcInfo environment. Powerful
map algebra tools, tools for surface modelling and Arc
Macro Language (AML) were used in the process of
building specific models.
The analytical process is simply presented as follows.
The source of information for building DEM was a forest
topographic map in scale 1:10,000 with contour intervals
of 20 m. Contours and geographic objects
(compartment boundaries, roads, stream network) were
digitized on-screen in the ArcView 3.0a. DEM used in
calculating skyline yarding distances was built by ap-
J. FOR. SCI., 47, 2001 (7): 307–313 307