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Cable-based technologies are the backbone for logistics of timber or construction material on impassable terrain. In Central Europe, the use of standing skylines with pre-stressed, both-sided fixed-anchor cables and multi-span configurations with internal intermediate supports is common. To ensure a safe and cost-effective set-up for cable road operations, it is essential to identify and compute the properties of the skyline (e.g. load path, tensile forces). This task is challenging because it requires dealing with the non‐linear behaviour of the cable structure under the load and has to include all significant physical effects. Several approaches have previously been proposed as practical solutions, however not all physical effects were covered by those approaches, such as the inclination-dependent elastic prolongation of the cable or the longitudinal deflection of the sagging carriage. With our new proposed approach, we aim to close this gap of knowledge, and consider all relevant physical effects. We present a non-linear approach that is able to compute the properties of a wide range of standing skyline configurations, including those with additional cables. This approach offers an extensive solution and a flexible framework for considering individual configurations or particularities by adding equations to the equation system.
Christian Knobloch; Leo Gallus Bont. A new method to compute mechanical properties of a standing skyline for cable yarding. PLOS ONE 2021, 16, e0256374 .
AMA StyleChristian Knobloch, Leo Gallus Bont. A new method to compute mechanical properties of a standing skyline for cable yarding. PLOS ONE. 2021; 16 (8):e0256374.
Chicago/Turabian StyleChristian Knobloch; Leo Gallus Bont. 2021. "A new method to compute mechanical properties of a standing skyline for cable yarding." PLOS ONE 16, no. 8: e0256374.
Efficient forest management, and wood production in particular, requires a forest road network of appropriate density and bearing capacity. The road network affects the choice of a suitable extraction method and the length of the transport route from the forest, while the road standard defines the truck type that can be used. We evaluate the forest road network’s economic suitability for harvesting operations in the entire Swiss forest, an area of about 13,000 km2 covering a range of topographies, based on the Swiss National Forest Inventory’s (NFI) forest road dataset. This dataset is based on information from an interview survey with the local forest services and includes all forest roads in Switzerland capable of carrying trucks. Extraction options and hauling routes are analysed together; thus, the entire logging process is examined. Model results include maps of the most suitable extraction method; extraction costs; hauling costs; and a suitability map based on a combination of the results. While the larger part of the Swiss forest is classified as “suitable” for economic harvesting operations, significant portions also fall into the “limited suitability” and “not suitable” categories. Our analysis provides an objective, country-wide, spatially explicit assessment of timber accessibility. The resulting suitability map helps identify areas where timber harvesting is economic using the current forest road network, and where it is not. The model results can be used in road network planning and management, for example, by comparing road-network re-design scenarios, and compared to the spatial distribution of available wood volume.
Marielle Fraefel; Leo G. Bont; Christoph Fischer. Spatially explicit assessment of forest road suitability for timber extraction and hauling in Switzerland. European Journal of Forest Research 2021, 1 -15.
AMA StyleMarielle Fraefel, Leo G. Bont, Christoph Fischer. Spatially explicit assessment of forest road suitability for timber extraction and hauling in Switzerland. European Journal of Forest Research. 2021; ():1-15.
Chicago/Turabian StyleMarielle Fraefel; Leo G. Bont; Christoph Fischer. 2021. "Spatially explicit assessment of forest road suitability for timber extraction and hauling in Switzerland." European Journal of Forest Research , no. : 1-15.
Wood fuel has become central in environmental policy and decision-making processes in cross-sectoral areas. Proper consideration of different types of woody biomass is fundamental in forming energy transition and decarbonization strategies. We quantified the development of theoretical (TPs) and sustainable (SPs) potentials of wood fuel from forests, trees outside forests, wood residues and waste wood in Switzerland for 2020, 2035 and 2050. Ecological and economic restrictions, timber market situations and drivers of future developments (area size, tree growth, wood characteristics, population growth, exporting/importing (waste wood)) were considered. We estimated a SP of wood fuel between 26.5 and 77.8 PJ/a during the three time points. Results demonstrate that the SP of wood fuel could be significantly increased already in the short term. This, as a moderate stock reduction (MSR) strategy in forests, can lead to large surpluses in SPs compared to the wood fuel already used today (~36 PJ/a), with values higher by 51% (+18.2 PJ) in 2020 and by 59% (+21.3 PJ) in 2035. To implement these surpluses (e.g., with a cascade approach), a more circular economy with sufficient processing capacities of the subsequent timber industries and the energy plants to convert the resources is required.
Matthias Erni; Vanessa Burg; Leo Bont; Oliver Thees; Marco Ferretti; Golo Stadelmann; Janine Schweier. Current (2020) and Long-Term (2035 and 2050) Sustainable Potentials of Wood Fuel in Switzerland. Sustainability 2020, 12, 9749 .
AMA StyleMatthias Erni, Vanessa Burg, Leo Bont, Oliver Thees, Marco Ferretti, Golo Stadelmann, Janine Schweier. Current (2020) and Long-Term (2035 and 2050) Sustainable Potentials of Wood Fuel in Switzerland. Sustainability. 2020; 12 (22):9749.
Chicago/Turabian StyleMatthias Erni; Vanessa Burg; Leo Bont; Oliver Thees; Marco Ferretti; Golo Stadelmann; Janine Schweier. 2020. "Current (2020) and Long-Term (2035 and 2050) Sustainable Potentials of Wood Fuel in Switzerland." Sustainability 12, no. 22: 9749.
Cable-based technologies have been a backbone for harvesting on steep slopes. Computing the layout of a single cable road requires considering the standards of structural design, aiming to (1) guarantee structural safety, and (2) provide the required serviceability. Currently applied analysis methods, such as the Pestal method, are unprecise. Alternatively, methods based on the catenary, such as Zweifel or Irvine, are better suited to analyze and predict load path and occurring forces for skylines anchored fix on both ends. However, studies that validate those catenary analyses (concurrently load path and forces) are rare and were not carried out under realistic heavy load conditions. Therefore, the aim of the project was to validate the catenary analyses under realistic, heavy load conditions for cable roads with multiple spans. In two case studies in Switzerland, the deflection in every span as well as the skyline tensile force at the anchor were measured for different load configurations and compared with theoretical computations of Zweifel and Pestal. The approach of Zweifel maps the mechanical properties realistic. However, as proven by our measurements, it slightly overestimated the deflection and the skyline tensile forces because the friction on the supports was neglected (between skyline and saddle). The deflections calculated with the Pestal formulas were significantly larger than the measured values, in particular with heavy load and in large spans. Our measurement studies confirmed that the mechanical properties of a cable road can be described adequately with the algorithm by Zweifel. However, it should be further developed with the inclusion of effects like the friction to improve the efficiency, safety and cost-performance ratio in cable road planning.
Leo Gallus Bont; Laura Ramstein; Fritz Frutig; Janine Schweier. Validation of Catenary-based Methods for Cable Road Layout Planning. Environmental Sciences Proceedings 2020, 3, 102 .
AMA StyleLeo Gallus Bont, Laura Ramstein, Fritz Frutig, Janine Schweier. Validation of Catenary-based Methods for Cable Road Layout Planning. Environmental Sciences Proceedings. 2020; 3 (1):102.
Chicago/Turabian StyleLeo Gallus Bont; Laura Ramstein; Fritz Frutig; Janine Schweier. 2020. "Validation of Catenary-based Methods for Cable Road Layout Planning." Environmental Sciences Proceedings 3, no. 1: 102.
Cable-based technologies have been a backbone for harvesting on steep slopes. The planning of a cable road is a complex task. It essentially comprises the definition of the start and end points of a cable road, as well as the intermediate supports. It must be ensured that the permissible forces (in particular, skyline tensile forces) are not exceeded, that there is a sufficient clearance between the load path and the ground, that suitable anchor trees are found, and that at the same time the number of intermediate supports is minimized as far as possible. On the other hand, for ergonomic and silvicultural reasons (work safety, damages to the forest), the skyline should be as high as possible. In practice, the search for a solution is often iterative; especially with long lines, several attempts may be necessary until a good line is found. The presented QGIS (free and open-source cross-platform desktop geographic information system) plugin searches automatically for the optimal cable road layout, so the planning process can be considerably simplified and obtained solutions are more cost-efficient. The plugin is designed for Central European conditions and assumes a standing skyline (fixed anchored skyline at both ends). For the calculation of the mechanical properties of the skyline, a close to catenary method is used (Zweifel 1960). When testing the feasibility of the cable line, care is taken that (1) the maximum permissible stresses in the skyline are not exceeded, (2) there is a minimum distance between the load path and the ground, and (3) when using a gravitational system, there is a minimum inclination in the load path. The newly developed method calculates the load path curve and the forces occurring in it more accurately than other tools available on the market. We further present a method to identify potential support and anchor trees directly from remote sensing data, which we aim to integrate in a further plugin. This ensures that there are effectively trees at the proposed intermediate positions and that the solution can be implemented in practice.
Leo Gallus Bont; Laura Ramstein; Janine Schweier; Hans Heinimann. A QGIS Based Workflow for Optimized Cable Road Layout Planning. Environmental Sciences Proceedings 2020, 3, 103 .
AMA StyleLeo Gallus Bont, Laura Ramstein, Janine Schweier, Hans Heinimann. A QGIS Based Workflow for Optimized Cable Road Layout Planning. Environmental Sciences Proceedings. 2020; 3 (1):103.
Chicago/Turabian StyleLeo Gallus Bont; Laura Ramstein; Janine Schweier; Hans Heinimann. 2020. "A QGIS Based Workflow for Optimized Cable Road Layout Planning." Environmental Sciences Proceedings 3, no. 1: 103.
Managing forests for ecosystem services and biodiversity requires accurate and spatially explicit forest inventory data. A major objective of forest management inventories is to estimate the standing timber volume for certain forest areas. In order to improve the efficiency of an inventory, field based sample-plots can be statistically combined with remote sensing data. Such models usually incorporate auxiliary variables derived from canopy height models. The inclusion of forest type variables, which quantify broadleaf and conifer volume proportions, has been shown to further improve model performance. Currently, the most common way of quantifying broadleaf and conifer forest types is by calculating the proportions of the corresponding areas of the canopy cover. This practice works well for single-layer forests with only a few species, but we hypothesized that this is not best practice for heterogeneously structured and mixed forests, where the area proportion does not accurately reflect the timber volume proportion. To better represent the broadleaf and conifer volume proportions, we introduced two new auxiliary variables in which the area proportion is weighted by height information from a canopy height model. The main objectives of this study were: (1) to demonstrate the advantage of including forest type (broadleaf/conifer distinction) information in ordinary least squares regression models for timber volume prediction using widely available data sources, and (2) to investigate the hypothesis that including the broadleaf and conifer proportions, weighted by canopy height information, as additional auxiliary variables is favourable over including simple area proportions. The study was conducted in three areas in Switzerland, all of which have heterogeneously structured and mixed forests. Our main findings were that the best model performance can generally be achieved: (1) by deriving conifer and broadleaf proportions from a high-resolution broadleaf/conifer map derived from leaf-off airborne laser scanning data, and (2) by using broadleaf/conifer proportions weighted by height information from a canopy height model. Incorporating the so-derived conifer and broadleaf proportions increased the model accuracy by up to 9 percentage points in root mean square error (RMSE) compared with models not using any forest type information, and by up to 2 percentage points in RMSE compared with models using conifer and broadleaf proportions based solely on the corresponding area proportions, as done in current practice. Our findings are particularly relevant for mixed and heterogeneously structured forests, such as those managed to achieve multiple functions or to adapt effectively to climate change.
Leo Gallus Bont; Andreas Hill; Lars Waser; Anton Bürgi; Christian Ginzler; Clemens Blattert. Airborne-laser-scanning-derived auxiliary information discriminating between broadleaf and conifer trees improves the accuracy of models for predicting timber volume in mixed and heterogeneously structured forests. Forest Ecology and Management 2020, 459, 117856 .
AMA StyleLeo Gallus Bont, Andreas Hill, Lars Waser, Anton Bürgi, Christian Ginzler, Clemens Blattert. Airborne-laser-scanning-derived auxiliary information discriminating between broadleaf and conifer trees improves the accuracy of models for predicting timber volume in mixed and heterogeneously structured forests. Forest Ecology and Management. 2020; 459 ():117856.
Chicago/Turabian StyleLeo Gallus Bont; Andreas Hill; Lars Waser; Anton Bürgi; Christian Ginzler; Clemens Blattert. 2020. "Airborne-laser-scanning-derived auxiliary information discriminating between broadleaf and conifer trees improves the accuracy of models for predicting timber volume in mixed and heterogeneously structured forests." Forest Ecology and Management 459, no. : 117856.
The sustainable supply of timber is one of the most important forest ecosystem services and a decisive factor determining the long-term profitability of forest enterprises. If timber production is to be economically viable, there must always be a way to analyse forest stands and trees felled for exploitation with regard to the wood assortments they contain. Only then can the expected timber yields, achieved by various silvicultural strategies or actions and different sorting options, be quantified with sufficient accuracy. The SorSim assortment simulator was developed for forest practitioners and forest scientists in Switzerland to realistically simulate the sorting of individual trees and entire forest stands based on defined specifications. SorSim has a simple user interface and comes in a number of different language versions (G, E, F). The software is implemented in Java, making it platform-independent. It can be downloaded for free at (https://www.wsl.ch/en/projects/sortimentsimulator-sorsim.html). This article provides an overview of how the simulator works and demonstrates its potential applications based on a practical and a scientific example. A particular practical advantage is that the composition of the assortments of the planned harvests can be estimated according to quantity and value. When used in strategic planning and especially in research, SorSim provides a basis for analysing either long-term developments in yields from forest stands or silvicultural treatment methods. Based on an even-aged and a selection forest stand, the scientific example shows how strongly the assessment of the advantageousness of two different silvicultural strategies depends on the time when the calculation was made (using historical and current assortment revenues and timber harvesting costs). In particular, the combination of SorSim with timber harvest productivity models enables differentiated forest economic insights. Various approaches for value-based optimisation in the sorting of individual trees and for the optimal allocation of harvesting activities to defined customer demands are currently being examined as further SorSim developments.
Renato Lemm; Clemens Blattert; Stefan Holm; Leo Bont; Oliver Thees. Improving Economic Management Decisions in Forestry with the SorSim Assortment Model. Croatian journal of forest engineering 2019, 41, 71 -83.
AMA StyleRenato Lemm, Clemens Blattert, Stefan Holm, Leo Bont, Oliver Thees. Improving Economic Management Decisions in Forestry with the SorSim Assortment Model. Croatian journal of forest engineering. 2019; 41 (1):71-83.
Chicago/Turabian StyleRenato Lemm; Clemens Blattert; Stefan Holm; Leo Bont; Oliver Thees. 2019. "Improving Economic Management Decisions in Forestry with the SorSim Assortment Model." Croatian journal of forest engineering 41, no. 1: 71-83.
Cable yarding is the most commonly used technique for harvesting timber from steep terrain in central Europe. During the planning process, one important task is to define the cable road layout. This means that the harvesting technology and cable road location must be specified for a given timber parcel. Although managers must minimize harvesting costs, it is even more important that such work on forests reduces the potential for damage to the residual stand and ensures that environmental conditions remain suitable for regeneration. However, current methods are geared only toward minimizing harvesting costs and are computationally demanding and difficult to handle for the end user. These limitations hinder broad application of such methods. Further, the underlying productivity models used for cost estimation do not cover all conditions of an area and they cannot be applied over a whole harvesting area. To overcome these shortcomings, we present: (1) a multiobjective optimization approach that leads to realistic, practicable results that consider multiple conflicting design objectives, and (2) a concept for an easy-to-use application. We compare the practical applicability and performance of the results achieved with multiobjective optimization with those achieved with single-objective (cost-minimal) optimization. Based on these points, we then present and discuss a concept for a user-friendly implementation. The model was tested on two sites in Switzerland. The study produced the following major findings: (1) Single-objective alternatives have no practical relevance, whereas multiobjective alternatives are preferable in real-world applications and lead to realistic solutions; (2) the solution process for a planning unit should include analysis of the Pareto frontier; and (3) results can only be made available within a useful period of time by parallelizing computing operations.
Leo Gallus Bont; Sabrina Maurer; Jochen Ruben Breschan. Automated Cable Road Layout and Harvesting Planning for Multiple Objectives in Steep Terrain. Forests 2019, 10, 687 .
AMA StyleLeo Gallus Bont, Sabrina Maurer, Jochen Ruben Breschan. Automated Cable Road Layout and Harvesting Planning for Multiple Objectives in Steep Terrain. Forests. 2019; 10 (8):687.
Chicago/Turabian StyleLeo Gallus Bont; Sabrina Maurer; Jochen Ruben Breschan. 2019. "Automated Cable Road Layout and Harvesting Planning for Multiple Objectives in Steep Terrain." Forests 10, no. 8: 687.
One of the classic operations problems in forest management is to select the harvesting system and to plan the layout, which has a significant impact on overall operational and environmental efficiency. This paper addresses the design of a harvesting system in areas characterized by steep slopes requiring cable-based harvesting under central European conditions. We present two computationally efficient methods (designated as set-covering model SCM and bounded set-covering model BSCM) for solving problems of cable road layouts and comparing them with a previously developed model (CaMLOC). Formulating the problem as a type of location set-covering model allowed us to delineate a much smaller problem that was easier to solve. By applying the new model formulations, it is possible to identify mathematical optimal CR layouts for real-world forests areas up to 50 ha within a reasonable period of time and to even estimate the maximum gap in optimality (only with the BSCM approach).
Leo Gallus Bont; Richard L. Church. Location set-covering inspired models for designing harvesting and cable road layouts. European Journal of Forest Research 2018, 137, 771 -792.
AMA StyleLeo Gallus Bont, Richard L. Church. Location set-covering inspired models for designing harvesting and cable road layouts. European Journal of Forest Research. 2018; 137 (6):771-792.
Chicago/Turabian StyleLeo Gallus Bont; Richard L. Church. 2018. "Location set-covering inspired models for designing harvesting and cable road layouts." European Journal of Forest Research 137, no. 6: 771-792.
Despite relatively high road density in the forests of Switzerland, a large percentage of that road network does not fulfill best practice requirements. Before upgrading or rebuilding the road network, harvesting planners must first determine which areas have insufficient access. Traditional assessment methods tend to only report specific values such as road density. However, those values do not identify the exact parcels or areas that are inaccessible. Here, we present a model that assesses the economic suitability of each timbered parcel for wood-harvesting operations, including tree-felling and processing, and off- and on-road transport (hauling), based on the existing road network. The entire wood supply chain from forest (standing trees) to a virtual pile at the border of the planning unit was captured. This method was particularly designed for steep terrain and was tested in the Canton of Grisons in Switzerland. Compared with classical approaches, such as the road density concept, which only deliver average values, this new method enables planners to assess the development of a road network in a spatially explicit manner and to easily identify the reason and the location of shortcomings in the road network. Moreover, while other related spatially explicit approaches focus only on harvesting operations, the assessment method proposed here also includes limitations (road standards) of the road network.
Leo Gallus Bont; Marielle Fraefel; Christoph Fischer. A Spatially Explicit Method to Assess the Economic Suitability of a Forest Road Network for Timber Harvest in Steep Terrain. Forests 2018, 9, 169 .
AMA StyleLeo Gallus Bont, Marielle Fraefel, Christoph Fischer. A Spatially Explicit Method to Assess the Economic Suitability of a Forest Road Network for Timber Harvest in Steep Terrain. Forests. 2018; 9 (4):169.
Chicago/Turabian StyleLeo Gallus Bont; Marielle Fraefel; Christoph Fischer. 2018. "A Spatially Explicit Method to Assess the Economic Suitability of a Forest Road Network for Timber Harvest in Steep Terrain." Forests 9, no. 4: 169.
Optimal layout of a forest road network The road network is the backbone of forest management. When creating or redesigning a forest road network, one important question is how to shape the layout, this means to fix the spatial arrangement and the dimensioning standard of the roads. We consider two kinds of layout problems. First, new forest road network in an area without any such development yet, and second, redesign of existing road network for actual requirements. For each problem situation, we will present a method that allows to detect automatically the optimal road and harvesting layout. The method aims to identify a road network that concurrently minimizes the harvesting cost, the road network cost (construction and maintenance) and the hauling cost over the entire life cycle. Ecological issues can be considered as well. The method will be presented and discussed with the help of two case studies. The main benefit of the application of optimization tools consists in an objective-based planning, which allows to check and compare different scenarios and objectives within a short time. The responses coming from the case study regions were highly positive: practitioners suggest to make those methods a standard practice and to further develop the prototype to a user-friendly expert software.
Leo Bont. Optimales Layout einer Walderschliessung. Schweizerische Zeitschrift fur Forstwesen 2016, 167, 294 -301.
AMA StyleLeo Bont. Optimales Layout einer Walderschliessung. Schweizerische Zeitschrift fur Forstwesen. 2016; 167 (5):294-301.
Chicago/Turabian StyleLeo Bont. 2016. "Optimales Layout einer Walderschliessung." Schweizerische Zeitschrift fur Forstwesen 167, no. 5: 294-301.