Volume 20
Issue 4
Forestry
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
DOI:10.30825/5.ejpau.41.2017.20.4, EJPAU 20(4), #14.
Available Online: http://www.ejpau.media.pl/volume20/issue4/art-14.html
GIS MAPS AND ANALYSIS IN DESIGNING FOREST ROAD SYSTEM ON MOUNTAINOUS AREAS
DOI:10.30825/5.EJPAU.41.2017.20.4
Janusz Goł±b1, Bogdan Łuczkowski2
1 Department of Forest Engineering, Faculty of Forestry, University of Agriculture in Krakow, Poland
2 Department of Forest Engineering, University of Agriculture in Krakow, Poland
A forest road system is a basic element of a technical infrastructure which
enables conducting well-balanced forest management and meeting the postulates
of the sustainable environment development. The correct designing of such a system
for a specific mountainous forest area is a multi-layer activity, addressing
a range of environmental features in the existing and future configuration, including
but not limited to: relief, tree stand properties, hydrogeological conditions
and a condition of the existing water system. A modern and effective analytical
tool for geospatial data is GIS. The Forest Numerical Map Standard (FNM) contains
a lot of essential information so that the analyses performed are useful in the
road system optimisation.
This article presents basic analyses conducted against FNM of a specific transportation
area (Łopień forest area in Limanowa Forestry Inspectorate, Southern
Poland) and the Digital Elevation Model (DEM). By means of QGIS 2.12.0 Lyon,
thematic maps were created and basic calculations were carried out concerning:
the cataloguing of the existing state, technological typification of tree stands
and design of a new road system. These were, among others, the following tree
stand analyses: diversification of age, species composition, reserves, quantity
and planned timber acquisition. The following was also performed: physiographical
analyses concerning exposition and downslope, hydrographic analyses, presence
and localisation of nature reserves, building properties of a subsoil, the present
condition of the road system and a range of zones of making tree stands available.
Furthermore, the operation of tools is presented consisting in filtering the
features of elements for their selection, designing the route of new roads in
the system with consideration of important properties of the transportation area,
drawing a longitudinal profile of the terrain in the place of the designed road,
calculating longitudinal slopes of such profiles, visualising road functions
in the system on the map and other analyses.
Key words: GIS, forest road system, thematic maps, Forest Numerical Map data analysis.
INTRODUCTION
The functions of forests are outlined in the applicable legal acts [31] but forests must be made available appropriately in order to ensure fulfilling such functions [4, 10, 13, 20, 26]. It is implemented by means of a transport network which is adequately designed, built and maintained. Such a network consists of forest roads of varied functions and bearing capacities, operational and skidding trails and also, to a certain extent, by means of public roads, running inside forest areas (or in their vicinity). It is said that a road system is like a blood circulation system for the forest.
The correct planning of the road system making a forest available is aided by multi-aspect analyses performed based on the standard content of the Forest Numerical Map (FNM) by means of GIS technology [1–3, 11, 12, 15, 16, 19, 30]. It is a modern and simple tool which allows for the selective concentration of lots of critical information simplifying and justifying the localisation of specific road sections [17, 18, 23–25].
Subject: the use of a modern IT technology in designing forest road systems in mountains.
Objective: to present the possibility and purposefulness of the application of GIS tools in forest designing works, including but not limited to designing a road system in forests at the stage of the cataloguing of the existing state and preparing decisions on the localisation of new road sections.
GENERAL DESCRIPTION OF THE STUDY AREA
The said analyses were carried out for "Łopień" forest belonging to Limanowa Forestry Inspectorate (southern Poland), classified as one transport area. This terrain had to be treated integrally because it covers the area around the mountain summit with the same name and it is surrounded by private forests and private pastures and fields. A possibility of accessing public roads is extremely restricted because there are only two such places – in the southern and in the southern-east part of the forest.
Łopień Mountain has three summits with the height of the central summit of 951 m a.s.l. The part of the forest which is situated the lowest has the height of 460 m a.s.l. There are mostly steep, very steep and cliffy mountainsides but in the areas near the ridge the slope is locally very small.
The climate of the region in which the studied transport area is located is pluvial and nival, and affected by the continental climate. An average annual air temperature ranges from 2.8°C for high mountains to 7.4°C for Limanowa and sub-mountainous terrains. Normal precipitation according to Suliński’s formula [29], with summit coordinates N: 49°42’, E: 20°16’, ranges, depending on the altitude, from 840 to 1089 mm. Maximal precipitation is present in summer months and minimum precipitation can be observed in winter months. A snow cover remains from 85 to 140 days. A vegetative period ranges from 160 to 210 days [14, 21, 27].
In geological terms, this terrain belongs to Magurska Nappe which was formed from tertiary sandstone, slates and marls and to a smaller extent from cretaceous slates and sandstone [28].
The system of factors described determines the conditions for building and using roads in this terrain.
METHODOLOGY
The analyses presented provide information necessary for planning forest road systems in mountains according to the methodology applied in the National Forest Management “National Forests” (NF) but only at stages which are currently implemented as part of the “Expert reports on the optimisation and development of road infrastructure” for forestry inspectorates [6]. These are as follows: a stage of cataloguing the forest condition and recent road system, stage of technological typification of tree stands and a stage of localising new roads in the system. Gołąb and Plewniak [8] wrote about difficulties in the application of the methodology which has been used for 50 years. A partial loss of relevance was a consequence of the change in the principles of the forestry inspectorates functioning after political changes in Poland in the nineties of the previous century. At the same time, a powerful technological development supplied tools for the multi-aspect analysis of data included in the standard Forest Numerical Map (FNM). A highly efficient and popular tool is GIS programming. All the analyses and maps are prepared based on internal programme procedures QGIS 2.12.0-Lyon [7] and a few generally accessible sub-programmes functioning on this platform – “plugs-in”.
The data source is the Forest Arrangement Plan for the years 1 I 2006 to 31 XII 2015 for Limanowa Forestry Inspectorate [21] and the Digital Elevation Model (DEM) for this area.
THE APPLICATION OF GIS AT THE STAGE OF CATALOGUING THE CONDITION OF THE ROAD SYSTEM AND TREE STANDS
The cataloguing of the condition of the recent road system covers the description of the functions of respective roads, their categories, surface types, bearing capacity, length and width of road sections, contact points with public roads, load streams, and collecting essential information on tree stands.
There are some analyses presented below in the form of thematic maps describing: species composition, tree stand age, large timber distribution, localisation of roads and skidding trails, terrain exposition, slopes, zones of making tree stands available from roads with a specific skidding system (according to FNM and DEM).
In Figure 1 there is a species description of tree stands presented by indicating major species. Figure 2 presents an analysis of an average age of tree stands in twenty years’ classes.
|
Fig. 1. Major species in the tree
stands of the transport area |
|
Fig. 2. Age diversification of tree
stands |
The above analyses are carried out based on the information contained in the table of attributes of a layer describing respective tree stands in allocations.
The map below (Fig. 3.) demonstrates the route of roads and skidding trails in the terrain according to the classification and description in respective FNM layers.
|
Fig. 3. Existing transport routes |
If the table of attributes of a layer containing information on roads does not contain all required data, it is necessary to complete such information based on one’s own site inspection, so that the map analyses performed are complete and reliable (road category, surface type and the function of respective roads in the system).
|
Fig. 4. Terrain exposition |
Figure 4 presents the analysis of a terrain layer, which is directing slope lines in relation to the cardinal points. The analysis described uses DEM with 10m pixel. The mountainside exhibition is significant for the formation of thermal and humidity conditions on a given terrain, which, in turn, affects the bearing capacity of the bodies of roads on such areas.
Figure 5 presents the analysis of the downslope in DEM with 10 m pixel. A downslope determines, to a great extent, the management conditions and also the possibilities and costs of road building and maintenance.
|
Fig. 5. Downslopes |
The road system description requires to calculate basic descriptive coefficients. These are as follows: road system density index (g) and average distance between roads (b). In order to calculate these coefficients (at this stage they will refer to the existing system), it is possible to use a programme function which calculates basic statistical parameters for specific layers – we read a cumulative length of all the existing roads and cumulative forest area. In Figure 6 There are both sub-programme tables with statistics (separate analyses). The units in which these values are presented are determined in the global design settings. In this case length is determined in metres and area in square metres.
|
Fig. 6. Tables with statistics for the length analyses of the existing roads and branch areas |
Road system density (g), one of the fundamental parameters describing the system, is calculated according to the following formula (1):
|
where:
L – forest roads length
[m]
PL – forest
area [ha]
Based on the road system density index (g), it is possible to calculate another crucial parameter – an average distance between roads (b, according to formula 2):
|
where:
g – road system density
index [m·ha-1]
In Figure 7 there is presented the first stage of assigning the zones ranges of providing access to tree stands. The width of such zones is determined by the existing skidding technology. There is a procedure of creating buffers with a specific width for selected linear elements (forest roads existing in the road system). At further stages, the size of such buffers is modified because skidding routes must avoid protected elements, foreign creeks and enclaves and uphill skidding.
|
Fig. 7. The first stage of indicating the zones of providing access to tree stands from the existing roads |
THE APPLICATION OF GIS AT THE STAGE OF THE TECHNOLOGICAL TYPIFICATION OF TREE STANDS
At this stage of designing a forest road system the following is determined: a skidding technology and skidding measure types based on an average downslope on the transport area. On the basis of DEM it is possible to generate statistics concerning downslopes (including an average value) based on the map pixel. Below there are the results of such two calculations for DEM with a different pixel value – 20 m and 1 m, which affects the accuracy of the results obtained. Since the entirety of the available DEM extract is much larger than the transport area, the calculation scope must be limited by means of the ‘external boundary’ layer. The values of the statistics are saved by the programme in the table of attributes of the applied limiting layer (Fig. 8 and 9).
|
Fig. 8. Table of attributes of the ‘external boundary’ layer with statistics for downslopes (20m pixel) |
|
Fig. 9. Table of attributes of the ‘external boundary’ layer with statistics for downslopes (1m pixel) |
Average downslope with the use of DEM:
- for 20 m pixel: iave = 16°57’ (16.95°) = 30.48%;
- for 1 m pixel: iave = 17°12’ (17.20°) = 30.96%.
With a determined average downslope, it is possible to define the techniques and measures for skidding according to Table 1.:
Table 1. Recommended skidding technologies and measures depending on the average downslope for the Polish conditions (source: [22]) |
THE APPLICATION OF GIS AT THE STAGE OF LOCALISING CORRIDORS OF NEW ROADS IN THE SYSTEM
Corridors must be understood as the initial indication of the course of new roads in the terrain. Such localisations are recommended for the correct functioning of a future road system, and detailed road designs in such corridors will be created later on in a separate design process.
While commencing the road system optimisation, it is necessary to localise points on the transport area classified in the following three categories: points (or area elements): “negative”, “critical” and “positive”.
“Negative” points are points which must be avoided and there must not be roads in such points or in their immediate vicinity. These include: foreign enclaves (other owners), areas valuable in terms of nature or elements under legal protection (reserves, natural monuments, nesting zones of rare species of birds, animal lairs, documented stands of extremely rare species of plants). The said map is presented in Figure 10. For point elements, protective zones must be presented by means of the ‘buffer’ tool.
|
Fig. 10. Distribution of the nature protection elements on the transport area |
“Critical areas” are places in which roads may be problematic or dangerous both for the environment and for the road itself. This category includes very steep terrains, creeks and their springs, and soils which due to their particle size are not adequate for building purposes [9]. Building roads in such conditions may evoke uncontrolled mass movements (land-sliding) and changes in the local hydrological system; on the other hand, the building process and subsequent road maintenance will be more difficult and more expensive and the bearing capacity of the road body and surface will be low. One of the reasons are extensive earthworks which will change the mountainside statics. Yet another reason is using necessary advanced de-watering systems, collecting water from the road and discharging it in points and in a concentrated form on the mountainside. Dewatering systems require proper technologies and materials and frequent supervision, at the same time without a guarantee of the correct de-watering of forest road bodies in all weather conditions. It is advisable to note the synergic operation of a few critical factors occurring in the terrain simultaneously. The respective maps are presented in the following Figures: 11, 12 and 13.
|
Fig. 11. Downslope analysis – distribution boundary 20 degrees |
|
Fig. 12. Hydrographical network of the transport area – creeks, springs and their protective zones |
|
Fig. 13. Technical conditions for road building – combined analysis of downslopes, hydrographical zone and soil type |
“Positive” points are places in the terrain which should be made available by means of a road system after its optimisation. A main objective of the existence of roads in production forests is a possibility of transport means reaching specific tree stands. Access urgency is determined based on the planned timber acquisition specified in the current Forest Arrangement Plan (FAP) and anticipated timber acquisition in the forthcoming decades (based on the tree stand growth rate theory). The forest fire protection is not without meaning here. It may be performed by analysing tree stands in terms of their age, quantity and planned cutting sites, and adjustment of the existing species composition to the managed tree stand type (MTST) specified in FAP. If the species composition is not consistent with the recommended MTST, such tree stands will be transformed, providing a higher timber acquisition rate. The described failure to adjust the species composition to the recommended MTST can be observed in mountain forests frequently as spruce tree stands cultivated in habitats with a higher fertility rate than the requirements of this species. Fire recommendations define a maximal distance of an arbitrary place in the forest from roads which are used to reach a site on fire.
A map based of which it is possible to analyse the distribution of tree stands of a specific age is provided in Figure 2. (performed at the stage of cataloguing the current condition of the forest), and the remaining thematic maps including information on reserves, quantity, spruce share, size of planned cutting are provided in Figure 14–17. The anti-fire access to tree stands may be specified by the use of the “buffer” sub-programme but such an analysis is carried out in forests with a high fire risk.
|
Fig. 14. Timber reserves in given branches |
|
Fig. 15. Quantity of tree stands |
|
Fig. 16. Percentage share of a spruce in the species composition of tree stands |
|
Fig. 17. Anticipated timber acquisition in a decade – according to the valid FAP |
Figure 18 presents the ‘filter’ sub-programme window by means of which it is possible to select complex and detailed information. This example includes conditions enabling the presentation of the localisation of tree stands where spruce share is higher than 50%, an average age of a tree stand exceeds 50 years and the tree stand quantity is lower than 100m3∙ha-1. The logical operator ‘AND’ results in indicating tree stands which satisfy all three conditions simultaneously. Figure 19 presents the localisation of tree stands which satisfies the conditions of such a filter.
|
Fig. 18. Dialogue window of ‘filter’ tool
for conditional information selection |
|
Fig. 19. Map presenting tree stands
satisfying the filter conditions from Figure 18 |
Figure 20. presents the proposal of the road corridors localisation in a new road system against the points and areas from the following categories: “negative” and “critical”. The relief as well as the existence and spatial distribution of negative and critical points and areas is sometimes so complicated that the consideration of such all conditions simultaneously is not feasible. Therefore, a final shape of the designed road system depends on the professionalism and responsibility of a designer.
|
Fig. 20. Proposed road system against “negative” and “critical” areas |
|
Fig. 21. Proposed road system against
tree stands satisfying the filter conditions from Figure 18 |
Figure 21 presents the localisation of roads in a new road system against tree stands selected by means of the filter shown in Figure 18
A road system design ought to be characteristic for, among others, a prospective possibility of implementation. It is important that roads allocated along corridors indicated in the design reach parameters included in the ranges acceptable in technical standards. One of the fundamental road parameters is a gradeline – the designed corridor arrangements must enable designing a route so that a gradeline does not exceed the set maximum values. GIS system indirectly provides a possibility of determining terrain inclination in the designed corridors by means of DEM. It is necessary to use the ‘terrain profile’ sub-programme which draws longitudinal terrain profiles in corridors, based on which it is possible to control slopes. If a downslope is exceeded (Fig. 24.), and it cannot be compensated by earthworks to a reasonable extent, it is necessary to suggest a different corridor route.
Below, in Fig. 22 and 23, there is a sub-programme window and a longitudinal corridor profile with a working number 103, made by means of DEM with 1m pixel and an extract of a table with data to draw the above profile (distances and heights).
|
Fig. 22. A window with a terrain longitudinal profile for the corridor of road No 103 |
|
Fig. 23. Table of a terrain longitudinal
profile for corridor No 103 containing point distances and heights |
Table 2 includes downslope sizes calculated by means of Excel for corridor No 103 (for an initial section with the approximate length of 25 m). The output numerical data were copied from the table provided in Figure 23.
Table 2. Downslopes of the initial section of corridor No 103 |
slope in the average: |
||||
slope in the maximum: |
||||
slope in the minimum: |
||||
Figure 24 presents a manual method for specifying a downslope in corridor No 104, for a section in which significant exceeding of permissible inclination is anticipated.
|
Fig. 24. Manual method for the determination of a longitudinal downslope for the part of corridor No 104 |
Figure 25 presents the functions of road sections in the design of an optimised road system. The decisions on functions are reflected in the anticipated traffic rate, road parameters and distribution of a timber terminal.
|
Fig. 25. Functions of respective road sections in the optimised road system |
|
Fig. 26. A table with basic statistics for a layer containing all the roads in the optimised road system |
Figure 26 includes an output sub-programme window providing basic statistics for all the roads in a new, optimised road system. On the basis of the sum of the length of all the roads and a forest area of the transport space (as at the cataloguing stage), a density index of the designed road system is calculated as well as an average distance between roads in their new system (formula 3 and 4).
Forest roads length (L): 24 237.44
m
Forest
area (PL): 691.19 ha
(unchanged)
|
|
Denomination as in formula 1 and 2.
Figure 27 presents the access zones of tree stands from all the roads after the road system optimisation according to the accepted skidding technology.
|
Fig. 27. Providing access to tree stands by means of a new road system according to the accepted skidding technology |
By using ‘Qgis2threejs’ sub-programme (with a repository) it is possible to perform a 3D visualisation of the developed transport area and designed road system. A user may choose visible elements, zoom in and rotate a view.
|
Fig. 28. 3D visualisation of the transport area from the north |
CONCLUSIONS
GIS technology, as a standard of analysing and developing spatial environmental data, is also applied in the process of the optimisation of forest road systems. Designers must consider a lot of economic and environmental aspects so that the access to the forest is as good as possible, with environmental costs at the lowest level [4, 10–13, 16]. Therefore, a detailed analysis includes the existing condition of the prepared transport area which orders the information and determines an initial condition of the forest as a whole [17]. Information on the relief, hydrogeological conditions, tree stands and shape and conditions of road systems is very interesting. In order to design the course of corridors correctly, it is necessary to indicate places and areas which are determined as “negative”, “critical” and “positive”. According to the authors, what is most difficult here is to adjust the course of corridors to the relief in order to achieve the permissible longitudinal inclination of designed roads. A solution here can be a sub-programme (a plug-in) which would aid marking the line of a constant slope. The programme used by the authors (Open Source) lacks such a plug-in in the official repository. Hence, it is required to perform the additional control of the size of longitudinal slopes for the designed corridors.
In the road system design presented above, the achieved road system density index, untypically for the Polish mountainous conditions, is relatively high [5]. It may be stated that it is a maximum variant and a necessity must be considered for building roads in all the designed localisations and correcting the course of some corridors (e.g. corridor No 104, Fig. 24). Additionally, based on a harvesting size and removal urgency (Fig. 17 and 19), one must decide on the sequence of building sections, distributing building costs into a few or several years. Firstly, main removal roads and depots must be created, and then some side roads will be built.
It must be noted that it is crucial to hold an updated and correct map (FNM) and DEM with a proper raster size because the quality of such materials determines a suitability value of the analyses conducted.
The analyses discussed in this study exceed the economic criteria of the optimisation of road systems in forests which have been applied so far and it is an unquestionable asset. Nevertheless, there are no clear and suitable criteria for determining an optimal road system density in the specific conditions of the transport area. There is also a lack of any set of analyses which is, in fact, obligatory while performing a design of the optimisation of forest road systems in mountains.
Conclusions
- A multi-layer analysis of information included in FNM provides strong prerequisites for the optimal distribution of respective road corridors in the designed road system in mountain forests.
- With the consideration of the current functions and needs of forests, the method and type of information gathered and technical possibilities of data processing and visualisation, a GIS tool is very useful in the analysis of the condition of the existing forest and planning forest road systems.
- Soil classification provided in FNM is not relevant for the direct assessment of a building suitability of local soils. It also describes building conditions but does not replace information obtained from soils science. Additional preparation of such data is required.
It is necessary to select and describe updated criteria for determining the optimal density of the forest road system.
Acknowledgements
This work was financed by the Department of Forest Engineering University of Agriculture in Kraków.REFERENCES
- Allen D.W., 2013. GIS Tutorial 2: Spatial Analysis Workbook. Esri Press, pp. 344.
- Bałazy R., 2010. Analizy przestrzenne w praktyce leśnej [Spatial analysis in forest management practice] [in:] Okła K. (ed.) Geomatyka w Lasach Państwowych. Cz. 1. Podstawy [Geomatics in the State Forests. Vol. 1. The Basics]. Centrum Informacyjne Lasów Państwowych, Warszawa, pp. 561 [in Polish].
- Chung W., Stuckelberger J., Aruga K., Cundy T.W., 2008. Forest road network design using a trade-off analysis between skidding and road construction costs. Canadian Journal of Forest Research, 8(3), 439–448.
- Czerniak A. (ed)., 2013. Wytyczne prowadzenia robót drogowych w lasach. [The guidelines of roadworks in the forests]. Wydawnictwo Ośrodek Rozwojowo-Wdrożeniowy LP w Bedoniu, pp. 124 [in Polish].
- Dzikowski J., 2006. Sieć dróg leśnych i szlaków operacyjnych [A network of forest roads and operational trails] [in:] Drogi leśne. Poradnik techniczny. [Forest roads. Technical guide]. Wydawnictwo Ośrodek Rozwojowo-Wdrożeniowy LP w Bedoniu, 22–29 [in Polish].
- „Ekspertyza optymalizacji i rozwoju infrastruktury drogowej nadleśnictwa Brynek. Obręb Brynek. Stan na 1 stycznia 2012”. 2012. [Expertise optimization and development of road infrastructure forest district Brynek. Precinct Brynek. Status on January 1, 2012]. Biuro Urządzania Lasu i Geodezji Leśnej w Krakowie. Computer printout. [in Polish].
- Gandhi U. 2016. Making a Map. Web site. URL: http://www.qgistutorials.com/en/docs/making_a_map.html, [online 21 July 2016].
- Gołąb J., Plewniak J. 2014. Aktualne uwarunkowania kształtowania sieci dróg leśnych w górach. [Current conditioning of the forming of forest road networks in the mountains]. Infrastructure and Ecology of Rural Areas. II/1, 195–206 [in Polish].
- Gołąb J., Plewniak J., Słowik-Opoka E., 2015. Wykorzystanie opisów glebowych zawartych w operacie urządzenia lasu w planowaniu sieci dróg leśnych [Use of soil descriptions contained in the forest management plan in forest road network planning]. Sylwan, 159 (6), 461–468. [in Polish].
- Hayati E., Majnounian B., Abdi E., 2012. Qualitative evaluation and optimization of forest road network to minimize total costs and environmental impacts. iForest 5, 121–125 [online 2012-06- 05] URL: http://www.sisef.it/iforest/contents/? id=ifor0610-009.
- Heralt L., 2002. Using the ROADENG system to design an optimum forest road variant aimed at the minimization of negative impacts on the natural environment. Journal of Forest Science, 48 (8), 361–365.
- Hosseini S.A., Mazrae M.R., Lotfalian M., Parsakhoo A., 2012. Designing an Optimal Forest Road Network by Consideration of Environmental Impacts in GIS. Journal of Environmental Engineering and Landscape Management, 20, 1, 58–66, DOI: 10.3846/16486897.2012.662748.
- Hruza P., 2003. Optimization of forest road network under principles of functionally integrated forest management. Journal of Forest Science, 49 (9), 439–443.
- Kondracki J., 2011. Geografia regionalna Polski. Wyd. 3 – uzupełnione. [Regional Geography of Poland. Ed. 3 – completed]. Warszawa, Wydawnictwo Naukowe PWN. pp. 444 [in Polish].
- Kooshki M., Hayati E., Rafatnia N., Ahmadi M.T., 2012. Using GIS to evaluate and design skid trails for forest products. Taiwan Journal of Forest Science, 27(1), 117–124.
- Kotro M., Koci P., Haxhi A., 1996. Extension of the road network in our mountain forest areas. Ecological, technical and social aspects. In: Proceedings of the Seminar on Environmentally Sound Forest Roads and Wood Transport, Sinaia, Romania, 78–86.
- Łuczkowski B., 2012. Projektowanie sieci dróg leśnych wspierane narzędziami GIS na przykładzie kompleksu leśnego Łopień w Nadleśnictwie Limanowa [Designing forest Road networks supported with tools GIS on the ex ample of a forest complex Łopień at the Forestry District Limanowa]. Master thesis - computer printout. Department of Forest Engineering University of Agriculture in Kraków [in Polish].
- Martin A.M., Owende P.M.O., Holden N.M., Ward S.M., O'Mahony M.J., 2001. Designation of timber extraction routes in a GIS using road maintenance cost data. Forest Products Journal, 51(10), 32–38.
- Najafi A., Sobhani H., Saeed A., Makhdom M., Mohajer M.M. 2008. Planning and assessment of alternative forest road and skidding networks. Croatian Journal of Forest Engineering, 29 (1), 63–73.
- Olsson L., 2007. Optimal upgrading of forest road networks: scenario analysis vs. stochastic modelling. Forest Policy and Economics, 9(8), 1071–1078.
- Plan Urządzania Lasu na lata 1.01.2006 do 31.12.2015. Nadleśnictwo Limanowa, Obręb leśny Limanowa. Stan na 1.01.2006 r. [Forest Management Plan for the period 1.01.2006 to 31.12.2015. Forest District Limanowa, Limanowa Precinct forest. Status on 1.01.2006]. Computer printout [in Polish].
- Plewniak J., Gołąb J., 2017. Gospodarczo-techniczne uwarunkowania procesu projektowania szlaków zrywkowych w lasach górskich [Farm and technical conditions of skidding trails designing in the mountain forests]. Infrastructure and Ecology of Rural Areas, I/1, 85–99 [in Polish].
- Przewodnik GIS do Interaktywnego Narzędzia Edukacyjnego „Transfer wiedzy w zakresie zrównoważonego rozwoju, Teoria – Praktyka, Alpy – Karpaty”. 2011. [GIS Guide to Interactive Educational Tools „Transfer of knowledge in the field of sustainable development, Theory – Practice, the Alps – Carpathians”]. Department of GIS, Cartography and Remote Sensing, Institute of Geography and Spatial Management of the Jagiellonian University, Kraków. Computer printout, pp. 29 [in Polish].
- Rogers L.W., 2005. Automating Contour-Based Route Projection for Preliminary Forest Road Designs using GIS. Thesis, University of Washington.
- Scott L.M., Janikas M.V., 2009. Spatial Statistics in ArcGIS. In: M.M. Fischer and A. Getis (eds.), Handbook of Applied Spatial Analysis: Software Tools, Methods and Applications, DOI 10.1007/978-3-642-03647-7_2.
- Sedlak O., 1983. General principals of planning forest road nets. FAO, 14 (1), 17–36.
- Sikorska E., 2006. Siedliska leśne. Cz. II. Siedliska obszarów wyżynnych i górskich [Forest habitats. Vol. II. Habitat areas of upland and mountains]. Publishing House Academy of Agriculture in Kraków, pp. 154 [in Polish].
- Stempień-Sałek M., 2006. Zewnętrzne Karpaty Zachodnie. Beskidy, cz. 2 [External Western Carpathians. Beskids, vol. 2]. Przyroda Polska, 11, 34–35 [in Polish].
- Suliński J., 1999. Wzór empiryczny opisujący zmienność obszarową normalnego rocznego opadu atmosferycznego na terenie Polski [Empirical formula describing the variability of the normal annual precipitation in Poland]. Acta Agraria et Silvestria series Silvestris, 37, 79–97. [in Polish].
- Tucek J., Pacola E., 1999. Algorithms for skidding distance modeling on a raster digital terrain model. Journal of Forest Engineering 10 (1), 67–79.
- Ustawa o lasach, 1991, tekst ujednolicony. [Forest Act, 1991, consolidated text]. Dz.U. z 2011 nr 12 poz. 59 [in Polish].
Accepted for print: 30.12.2017
Janusz Goł±b
Department of Forest Engineering, Faculty of Forestry, University of Agriculture in Krakow, Poland
al. 29 Listopada 46
31-423 Kraków
Poland
email: rlgolab@cyf-kr.edu.pl
Bogdan Łuczkowski
Department of Forest Engineering, University of Agriculture in Krakow, Poland
al. 29-listopada 46
31-425 Kraków
Poland
email: bogdanluczkowski88@gmail.com
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