Decision Making in Forest Road Planning Considering Both Skidding and Road Costs: a Case Study in the Hyrcanian Forest in Iran

Hyrcanian forest is the only forest designated for commercial timber production in Iran. Ground-based skidding is the most common extraction system used in the forest, though large parts of the forest are still inaccessible due to the low road density (1-2 m ha-1). To facilitate timber harvesting in the forest, it has been proposed to increase the road density up to 20 m ha-1. The aim of this study was to incorporate the estimated skidding costs through a time study into an existing transportation planning tool, NETWORK 2000, to help decision making on forest road building. We applied this method to the Gorazbon district in the Hyrcanian forest, where 244 links were built for the analysis. The best solution found by NETWORK 2000 indicates that all the proposed roads should be built to minimize the total skidding and road building cost

Decision making in forest road planning considering both skidding and road costs: a case study in the Hyrcanian Forest in Iran

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Strategies to Mitigate the Effects of Soil Physical Disturbances Caused by Forest Machinery: a Comprehensive Review

Purpose of Review: Ground-based mechanized forest operations can cause severe soil disturbances that are often long lasting and detrimental to the health of forested ecosystems. To reduce these soil disturbances, focus is being increasingly directed at identifying and using appropriate mitigation techniques. This systematic review considered 104 scientific articles and reported the main findings according to four core themes: terrain-related factors, operational planning, machine modifications, and types of amendments used to mitigate machine-induced soil impacts. Recent Findings: For terrain-related factors, most severe disturbances occur on machine operating trails exceeding 20% slope and that soil bulk density and rut depth show greater increases in fine-textured soils. When considering operational planning, trafficability maps proved to be helpful in reducing the frequency and magnitude of soil damages as well as the length of trails needed within harvest sites, especially if they are regularly updated with weather information. Machine modifications, through high flotation tires, use of extra bogie axle, lower inflation pressure, and use of steel flexibles tracks, are highly researched topics because of the considerable upside in terms of machine ground pressure distribution and increased traction. Two main types of amendments emerged to mitigate soil disturbances: brush mats and mulch cover. Brush mats created from harvesting debris can spread the load of a machine to a greater area thereby lowering peak loads transferred to the soil. Brush mats of 15–20 kg m−2 are being recommended for adequate soil protection from harvesting operations. Summary: To conclude, we outline recommendations and strategies on the use of soil mitigation techniques within cut-to-length forest operations. New research opportunities are also identified and discussed. Considering single factors causing machine-induced soil disturbances remains important but there is a pressing need for having a multi-disciplinary approach to tackle the complex problems associated with machine/soil/plant interactions

Effects of soil compaction on seedling morphology, growth, and architecture of chestnut-leaved oak (Quercus castaneifolia)

Soil compaction following traffic by heavy-timber harvesting machinery usually causes an increase in soil strength, that is a stress factor negatively affecting the growth of newly germinated seedlings. This study used a soil strength experiment carried out in a greenhouse to test the hypotheses that increasing soil strength would adversely affect seedling morphology and alter seedling architecture by changing biomass allocation patterns. We explored the effects of soil compaction in a loam to clay-loam textured soil with optimal conditions of water on a continuous scale (0.2-1.0 MPa penetration resistance) on growth responses of the deciduous Quercus castaneifolia (C.A.Mey). Both above- and below-ground seedling characteristics, including size and biomass, were negatively affected by soil compaction. At the highest intensity of compaction, size and growth were reduced by 50% compared to controls; negative effects were typically more severe on below-ground (i.e., the length and biomass of the root system) than on above-ground responses. Increasing soil strength did not change above- and below-ground biomass allocation patterns (i.e., root mass ratio, root:shoot ratio, specific root length), resulting in unchanged seedling architecture. Strong adverse effects were already evident in the low-intensity compaction treatment and no critical soil strength threshold was observed. We conclude that root and height growth in Q. castaneifolia seedlings is limited by any increase of soil strength, though no evidence for the disruption of a functional equilibrium between above- and below-ground plant portions was found up to soil strengths of 1.0 MPa, at least under optimal water supply

Decision making in forest road planning considering both skidding and road costs: a case study in the Hyrcanian Forest in Iran

Hyrcanian forest is the only forest designated for commercial timber production in Iran. Ground-based skidding is the most common extraction system used in the forest, though large parts of the forest are still inaccessible due to the low road density (1-2 m ha-1). To facilitate timber harvesting in the forest, it has been proposed to increase the road density up to 20 m ha-1. The aim of this study was to incorporate the estimated skidding costs through a time study into an existing transportation planning tool, NETWORK 2000, to help decision making on forest road building. We applied this method to the Gorazbon district in the Hyrcanian forest, where 244 links were built for the analysis. The best solution found by NETWORK 2000 indicates that all the proposed roads should be built to minimize the total skidding and road building costs

Soil recovery assessment after timber harvesting based on the sustainable forest operation (SFO) perspective in iranian temperate forests

Minimizing the impact of timber harvesting on forest stands and soils is one of the main goals of sustainable forest operation (SFO). Thus, it is necessary to make an accurate assessment of forest operations on soil that is based on the SFO perspective. The present study was conducted according to SFO principles to investigate the time required for the natural recovery of soil after disturbance by skidding operations in some Iranian forests. The physical, chemical, and biological properties of soil found in abandoned skid trails from different time periods were compared with undisturbed forest soils. The soil bulk density, the penetration resistance, and the microporosity of a 25-year-old skid trail were 8.4-27.4% and 50.4% greater, and the total porosity, macroporosity, and soil moisture were 1.9-17.1% and 4.6% lower than the undisturbed area. In a 25-year-old skid trail, the values of pH, Electrical conductivity (EC), C, N, available P, K, Ca, and Mg, earthworm density, and biomass were lower than in the undisturbed area, and the C/N ratio value was higher than in the undisturbed area. High traffic intensity and slope classes of 20-30% in a three-year-old skid trail had the greatest impact on soil properties. In order to have sustainable timber production, SFO should be developed and soil recovery time should be reduced through post-harvest management operation