journal of forest science

Table 1. The factor values for passing points extracted by fuzzy reasoning inference mechanism
Passing points Factor values for passing points extracted by inference mechanism
(Points extracted by fuzzy factor_1 factor_2 factor_3 factor_4
reasoning inference mechanism) (m) (%) (m) (m)
A. 196 7.7 157 14.6
B. 196 7.2 142 12.1
C. 189 7.5 90 12.0
D. 194 7.0 173 14.4
E. 187 8.5 132 13.5
F. 199 6.0 116 11.6
G. 199 5.4 164 8.4
H. 194 7.6 118 10.6
CH. 194 7.8 94 14.2
I. 197 5.37 115 8.9
J. 187 3.3 157 5.8
By using a Vertical actor (V), we can take into account
the cost necessary to overcome the slope between
two cells. The value of V depends on the vertical relative
moving angle – VRMA (see ESRI 1994) and is defined
in our system as shown in ig. 5:
V = 1 if (0 ≤ VRMA ≤ 6)
V = ∞ if (6 < VRMA < 90)
V = 1 if (0 ≥ VRMA ≥–6)
V = ∞ if (–6 > VRMA >–90)
The VRMA is limited to 6 degrees following the maximum
gradient of hauling road acceptable for Slovak terrain
conditions.
RESULTS
The new cartographic model of skyline yarding distances
built for ArcInfo TM GRID environment and SDSS
system were verified in a called Zboj river included in
the working-plan area Zboj. The study area is approximately
2,400 ha in size and situated in the Bukovské
Vrchy Mountains in Eastern Slovakia. The area is configured
with high undulations and an average slope gradient
is 45%. Steep slopes above 40% occupy about 50%
of area.
Fig. 6. A forest road laid out using fuzzy reasoning system and
directional path distance model
The hauling road density is 26 m/ha, of which 22 m/ha
are not paved hauling roads. The density of permanent
ground skidding roads is about 17 m/ha. The calculated
forest road density and the theoretical value of area accessibility
show very good possibilities for opening the
forest up. Nevertheless, in terms of the forest tractor skidding
technologies used terrain conditions and existing
road structures indicate that average skidding tractor distance
is in reality very long, approximately 2,000 m (see
also comments in Introduction).
ig. 6 shows the recommended contour road proposal
compared with the existing roads. Points A ~ J are passing
points selected by using a fuzzy reasoning inference
mechanism which is based on linear functions for decision
rules. actor values for passing points extracted by
the inference mechanism can be seen in Table 1. Point
“P” is a starting point and “K” an ending point which is
selected by the user. It is apparent from the given figures
that the system takes into account terrain conditions in
the layout of roads and that the proposed output is very
similar to the existing road.
This system, which automatically lays out the forest
roads, was mainly designed to take into consideration
terrain conditions, but supplementary sources of information
can be used too. Difficult terrain features, e.g.
extreme slopes, rockiness, environmental barriers, places
where yarding distances exceed the technological
length of a cableway system route may be identified in
the model system. These defined features (negative barriers)
cause difficulties in the planning of new roads. The
system eliminates negative areas from being considered
and thus ensures that forest roads will avoid these areas.
The information derived about skidding distances can
support decision-making on where a new road is to be
located and where existing ground skidding roads can be
proposed for sanitation. The project of locating new sections
of hauling roads was based on the idea that the skyline
yarding distances between the new road and the
existing valley road or contour road should not exceed
the length of the maximum effective span for the proposed
cableway system route. LARIX 550 (Czech Republic
origin) is the most frequently used cableway
J. FOR. SCI., 47, 2001 (7): 307–313 311