Forest Harvesting Operations Research Articles

Multi-Stem Mechanized Harvesting Operation Analysis – Application of Arena 9 Discrete-event Simulation Software in Zululand, South Africa

Time studies were carried out on a stump-to-mill multi-stem Eucalyptus harvesting and transport operation in Zululand, South Africa in 2007. A simulation model (System 1) of this system was subsequently built using a commercial simulation software package (Arena 9) and data from the time studies incorporated into the model. Following this, two hypothetical stump -to-mill multi-stem models (Systems 2 and 3) were built using Arena 9 and parameterized input data. All models were found to adequately represent reality. Simulated harvesting system balance was improved through normalization of machine utilization in Systems 2 and 3. Production improvements were predicted with simulated timber production per month increasing by 31.1% and 30.8%, from System 1 with three trucks, to System 2 with four trucks, and System 3 with four trucks, respectively. Cost reduction was predicted, with the cost per unit of timber decreasing by 12.5% and 4.1%, from System 1 with three trucks, to System 2 with four trucks and System 3 with four trucks, respectively. Beneficial operational techniques were also confirmed using the simulation models. In the studied conditions delimbing and debarking of full trees into tree lengths at roadside with delimber-debarkers before cross-cutting and loading with a slasher was predicted to be $0.65/m3 cheaper than delimbing, debarking, and cross-cutting full trees into pulpwood with processors at the landing and then loading with a loader. Usability of Arena 9 in modeling forest harvesting operations was concluded as acceptable, but required detailed background logic inclusion.

Spatial and temporal modelling of aboveground carbon stocks using Landsat TM and ETM+ for a subboreal forest

Forest carbon (C) stocks and sequestration have become an important management consideration for countries with large forested regions. A series of Landsat Thematic Mapper (TM) images was obtained for the Aleza Lake Research Forest (ALRF) in subboreal British Columbia. Plot-based aboveground biomass and woody debris C stocks measured in 2003 and 2004 were related through regression analysis to TM and spatially explicit forest cover information. Two empirical models were developed, namely a biomass C regression model (BCRM) and a woody debris C regression model (WDCRM), with r2 values of 0.67 and 0.64, respectively. Uncertainties in C stock estimates were determined using a Monte Carlo uncertainty analysis. In 2003, the total C stocks in biomass and woody debris over the 6034 ha area were 588 ± 7 and 77 ± 2 kt, respectively. During the time period from 1992 to 2003, forest harvesting operations accounted for a loss of 39.9 ± 2.6 kt C, and remaining areas accounted for a gain of 31.3 ± 10.3 kt C. Therefore, there was a small and nonsignificant loss of 8.7 ± 10.6 kt C over this 11 year interval for the ALRF, implying that aboveground carbon stock losses associated with clearcuts were offset by carbon stock gains achieved through forest growth.

The Effects of Forest Harvest Operations on Mercury and Methylmercury in Two Boreal Streams: Relatively Small Changes in the First Two Years prior to Site Preparation

Forest harvest is hypothesized to increase the mercury (Hg) load in aquatic ecosystems. The Balsjö paired catchment study examined the outputs of methylmercury (MeHg) and total mercury (Hg(tot)) from two boreal catchments during the 2 y following forest harvest but prior to site preparation. This enabled us to separate the effect of the two operations that followed best management practices. Hg(tot) concentrations increased by approximately 15%, and fluxes by 20-30%. The MeHg concentrations and fluxes either declined or increased by up to 60%, depending on whether annual MeHg peaks during summer low flows were considered to have been influenced by forest harvest. The lack of a severalfold increase in Hg outputs after forest harvest, as reported from other sites, may be the result of minimal soil disturbance during the winter forest harvest operations. If so, there may be a greater Hg response after soil scarification to prepare for planting.

Use of mathematical models in forestry: Evaluation of ProFor model in three main forestry regions of South Africa

Timber harvesting operations in plantation forestry in South Africa are rapidly being mechanised. However, machine movement in forest plantations may negatively affect soil quality. The forestry industry is introducing mathematical models to enable it address, limit or at least predict soil damage. One of these mathematical models is the “ProFor” model. The study was conducted in four harvesting sites namely KwaZulu Natal; Eastern Cape and the Western Cape. The impact of mechanised harvesting equipment on soil quality was assessed by observing changes in soil bulk density and critical soil water content. The changes in soil physical properties were then compared with ProFor’s predictions. The results indicated that ProFor gave valid predictions for critical soil moisture content in most of the study sites. However, for observed increases in bulk density, ProFor predictions of soil damage were invalid (r2 = - 0.1). The model can be adopted by the South African forestry industry for tactical planning of forest harvesting operations. Additionally, ProFor can be of even more use if a separate algorithm is developed to be used for the prediction of soil compaction which is a common hazard in South African forestry. Key words: Bulk density, forest harvesting, ProFor, soil compaction.

Changes in benthic macroinvertebrate communities in upper catchment streams across a gradient of catchment forest operation history

The effects of forest harvesting on wet eucalypt forest stream macroinvertebrates were examined in Tasmania, Australia. Sites were selected in second to fourth order streams across a gradient of catchment forest harvesting history and in paired reference catchments. Historical data for every forest parcel (coupe) were obtained for each catchment, detailing forest operational type, area and year of operation, length of roads and number of stream road crossings. We observed substantial differences in macroinvertebrate community composition and abundance across the 14 site pairs. We observed higher abundances of orthoclad midges, Leptophlebiid mayflies and Elmid and Scirtid beetles, and reduced abundances of worms and Notonemourid stoneflies at forestry test sites, than at their paired reference sites. A consistent shift in community composition was observed for 12 of the 14 site pairs. This was accompanied by a shift in functional feeding group representation away from shredders at test compared to reference sites. Community compositional similarity was substantially higher between test than reference sites, with a reduction in community diversity among streams due to a history of upstream forestry. Community dissimilarity between paired test and reference sites was negatively correlated with the average parcel age and time since initial harvesting. We observed declines in abundance with increasing average coupe age of the mayfly family Leptophlebiidae and midge sub-family Chironominae at test sites relative to reference sites. Time since initial disturbance and the number of road crossings jointly accounted for 52% of the variance in paired-site Bray-Curtis dissimilarity values, with both variables negatively correlated with dissimilarity. We observed a shift related to catchment forestry disturbance in macroinvertebrate community composition away from taxa typical of south-east Australian ‘depositional’ headwater stream environments to greater representation of taxa characteristic of higher power, more ‘erosional’ stream reaches. This support the hypothesis of a transition from predominantly degradational responses to forest harvesting operations (in the geomorphological sense) in headwater streams toward transient ‘aggradational’ effects further downstream with concomitant biological responses.

Estimating forest harvesting operations to achieve sustainable rural development in Samarina (Greece)

Purpose of the work: Mountainous areas, with altitude over 700 m, intense relief and slopes between 16–20%, cover 43% of Greece and they are usually characterized by low population density and long-term unemployment. The Greeks have a dependent connection among environment, economy and society as the history illustrates. Many of Greece’s historic, cultural landscapes and native ecosystems have been degraded or isolated over the years. There is scientific evidence that Greece’s natural/semi-natural forested areas cannot be sustained without watersheds, ridges and other natural corridors that connect its native landscapes and ecosystems. Logging systems are really ancient by using often only mules or horses. The aim of the work is to estimate how harvesting systems should be technologically upgraded improving forest work and social wellness maintaining at the same time ecological sustainability. Approach: The study area is held at Samarina region, a mountainous area of Northern Pindos in Greece. Social data were colSocial data were collected with questionnaires and local visits for better understanding of human resources for forest authorities and other administrative information’s. DTM, Forest Inventory data and other GIS data have been derived by paper maps and previous studies. A registration of road-net and human resources within the protected area of Valia Kyrna and their contribution as factors for the sustainable development was used. The development of a Spatial Decision SupThe development of a Spatial Decision Support System that can concern all the conditions that are need in order to make an estimation of the optimal way of harvest a stand is really a challenge. Expected results: A GIS program is a powerful decision support tool in order to give the opportunity to the offices of Forestry to choose the optimal way of harvesting a stand and also to realize visually the effect’s of such a kind of work; that is going to be held to the inhabitants and to the tourists of the area.

Soil compaction caused by 450C Timber Jack wheeled skidder (Shefarood forest, northern Iran)

In forest harvesting operations usually after using skidding machinery (skidders), traces of soil damage in the form of soil compaction and wheel and logs ruts can be seen in the forest soil. Soil bulk density, which represents soil compaction, decreases soil porosity, infiltration rate and aeration and these in turn increase runoff and water erosion in the harvested area. On the other hand, a decrease in soil aeration prevents root growth and decreases the vegetative cover. In this study the changes in soil bulk density and relative soil compaction due to a different number of wheeled skidder passes from stump to landing for two soil types (clay soil with high and low liquid limits, CH, CL) are analyzed. The results showed that the effect of skidder traffic on an increase in soil bulk density at sample locations was significant (α = 0.05). The range of soil bulk density increases in sample pits due to a different number of machinery passes was from 15.8% to 62.6% compared to the control area. The findings of this research showed that the interaction effect of skidder traffic and soil type on soil bulk density changes was not significant. Also the highest significant increase in soil bulk density occurred at the first 11 passes in skidding trails and from this number of passes onwards there was no significant difference in the soil bulk density increase in sample locations.

Soil compaction due to forest harvest operations

The objective of this work was to determine, through the use of the bearing capacity model, the traffic effects of the forest harvest operations on the preconsolidation pressure (sigmap), during one cycle of the eucalyptus plantation. The work was conducted using undisturbed soil samples, collected at the surface of the A horizon and in the top of the B horizon of an Udult (PA), Aquox (FX) and Udox (LA) soils. The undisturbed soil samples were used in the uniaxial compression tests. The soil sampling was done before and after the harvest operations. The operations performed with the Forwarder caused greater soil compaction than the ones done with the Feller Büncher and Harvester. The percentage of soil samples, in the region with additional soil compaction, indicated that the Udult was the soil class more susceptible to soil compaction, followed by the Aquox and Udox. Despite Udult is the more susceptible to soil compaction, the regeneration of the soil structure in this soil class was more efficient than in Aquox. The percentage of soil samples with sigmap values in the region with additional soil compaction in 1996, 1998 and 2004, after harvest operations, indicated a sustainable forest exploration in this period.

Use of Beryllium‐7 to Document Soil Redistribution following Forest Harvest Operations

Rapid and reliable methods for documenting soil erosion associated with forest harvest operations are needed to support the development of best management practices for soil and water conservation. To address this need, the potential for using 7Be measurements to estimate patterns and amounts of soil redistribution associated with individual post-harvest events was explored. The 7Be technique, which was originally developed for use on agricultural land, was employed to estimate soil redistribution associated with a period of heavy rainfall within a harvested forest area located in the Lake Region of Chile (39 degrees 44'7'' S, 73 degrees 10'39'' W; 22% slope; and mean annual rainfall 2300 mm yr(-1)). The results provided by the 7Be technique were validated against direct measurements of soil gain or loss during the same period obtained using erosion pins. The information produced by the two approaches was similar. The results of this study demonstrate the potential for using 7Be measurements to document event-based erosion in recently harvested forest areas.

Soil Physical Changes Associated with Forest Harvesting Operations on an Organic Soil

The influence of forest operations on forest soil and water continues to be an issue of concern in forest management. Research has focused on evaluating forest operation effects on numerous soil and water quality indicators. However, poorly drained forested watersheds with organic soil surface horizons have not been extensively investigated. A study was initiated in the Tidewater region of North Carolina to gain a better understanding of the impact of harvesting operations on poorly drained organic soils. Soils on the study site, having >80% organic matter (OM) content to a depth of 60 cm below the soil surface, were classified as shallow organic soils. Soil physical properties were examined by collecting soil cores from control and treatment watersheds in a nested design. Compaction caused by the harvest operation increased bulk density (Db) from 0.22 to 0.27 g cm−3, decreased saturated hydraulic conductivity (ksat) from 397 to 82 cm h−1, and decreased the drained volume for a given water table depth. However, Db following the harvest remained low at 0.27 g cm−3 The drained volume at equilibrium following the lowering of the water table from the soil surface to a depth of 200 cm was reduced by 10% from that of control watershed as a result of harvesting.

Soil protection with logging residues during mechanised harvesting of native forests in Tasmania: a preliminary study

Summary In Tasmania, Australia, mechanised forest harvesting operations often use ‘cording’ to limit soil disturbance. This means logs are laid across the snig tracks, perpendicular to the flow of traffic, providing a rigid barrier between the machinery and the ground surface. At the conclusion of harvesting, the cording material is lifted using an excavator and burnt on site. This latter procedure enhances soil nutrition through the ‘ash-bed’ effect, whilst increasing the area of seedbed available for forest regeneration. To date, the efficacy of cording in protecting soil values remains largely untested. The shallow and stony nature of many forest soils, and the presence of logging residues and cording material along snig tracks, make the investigation of soil physical properties difficult. In response, this study was undertaken to assess the effectiveness of cording by using forest regeneration (density of seedlings and seedling height) as an indicator of productivity along former snig tracks protected with cording. Available seedbed (%) and seedling form, including the incidence of browsing and disease, were recorded and key soil chemical properties (0–10 cm soil depth: organic carbon, total nitrogen and total phosphorus), were measured. In the absence of physical soil testing, the theoretical distribution and attenuation of machine loads by the cording are discussed. Forest regeneration along the former snig tracks was consistently inferior in quantity and quality compared to that of the untrafficked control areas. This was attributed largely to: (a) a reduction in the available seedbed (%) due to incomplete combustion of the cording material and retention of logging residues, both on the ground surface and mixed with the upper soil layers, and (b) poor growing conditions—the combined effects of lowered organic carbon, nitrogen and phosphorus concentrations along the former snig tracks. Operational recommendations based on this study include: (a) avoiding trafficking of bare ground during the construction of cording, (b) beginning with a layer of small—diameter material to help spread machine loads more evenly and (c) where appropriate, leaving permanent snig tracks.

Does forest harvesting emulate fire disturbance? A comparison of effects on selected attributes in coniferous-dominated headwater systems

The emulation of natural disturbances is seen by many as an important management paradigm for achieving sustainable ecosystem management. To successfully emulate natural disturbances, managers must first have an understanding of the complex interactions that occur to the biophysical and chemical attributes of an ecosystem for both the natural and the “emulating” disturbance. The management of riparian ecosystems is an important issue faced by managers since the type of harvesting treatment can have a significant influence on the aquatic component. The removal or retention of riparian forests can have a direct influence on water quality and quantity, particularly on the smaller systems that are found at the headwaters of catchments, but do these treatments invoke a similar response as wildfire? To determine if emulation occurs, the affects of forest harvesting treatments and wildfire on temperature, water chemistry, summer stream flow, and sedimentation in headwater systems were compared using a meta-analysis. A statistically significant difference was found for temperature response between partial/selective harvesting and wildfire, but not after clear-cut harvesting. Water chemistry showed statistically significant differences for 11 out of 14 tested attributes, with dissolved organic carbon exhibiting the most marked difference. A significant difference was identified between clear-cut harvesting and wildfire for summer stream flow but not between wildfire and partial/selective harvest systems. Forest harvesting operations were found to emulate sedimentation through forest roads but not harvest treatment. Partial/selective harvest systems may offer the greatest emulation congruency versus clear-cut harvest systems in terms of overall headwater response and recovery. Partial/selective harvest systems combined with prescribed burning may provide managers with the best solution when attempting to emulate wildfire in headwater systems and reduce the detrimental impact of perturbation on these systems.

Modelling the effects of boreal forest landscape management upon streamflow and water quality: Basic concepts and considerations

Modelling and predicting potential impacts of forest harvest operations and wildfire on water quantity and quality are critical tools for forest managers. To make these predictions, the impacts of harvest operations and wildfire on model input parameters must first be quantified with measurements. In addition, output data are required to validate the model before any meaningful predictions can be made. This component of the Forest Watershed and Riparian Disturbance (FORWARD) project will closely associate hydrologic and water quality simulation modelling with intensive field monitoring of disturbance effects in forests of the Boreal Plain subregion of western Canada. The goal is to develop modelling procedures that can be used for predicting the impacts of forest operations and wildfires on water quantity and quality of stream runoff on the Boreal Plain. Key words: runoff, water quality, non-point source water quality modelling, hydrologic modelling, watershed management, riparian zone, forestry management.

A framework for analyzing workforce dynamics in forest harvesting in South Africa

Synopsis People are the industry's most valuable asset. However, due to its dynamic nature, labour cannot be owned but only rented. A framework for measuring, monitoring and managing labour dynamics is used and tested in forest harvesting operations in South Africa and the results presented. Overall, the workforce in forest harvesting is unstable: the median labour turnover (monthly basis) and absenteeism (daily basis) are 4 % and 6 %, respectively. Of further concern are: high instability in some individual contractor businesses (employees were much more stable with private grower companies than presently with contractors); and contractors not measuring and monitoring labour turnover. Labour turnover rates depend primarily on the conditions of employment offered by the contractor. The framework and results presented in this article are prerequisites for sustainable development. Efforts should be made to put appropriate short, medium and long term measures in place to reduce labour turnover and absenteeis...

Análise de danos de colheita de madeira em floresta tropical úmida sob regime de manejo florestal sustentado na Amazônia ocidental

Procurou-se identificar, qualificar e quantificar a intensidade de danos causados pela colheita florestal em uma área com floresta primária explorada (FPE), tendo com testemunha uma área com floresta primária não-explorada (FPNE), com 202 e 204 ha, respectivamente. Na FPNE, foram avaliados os danos decorrentes de causas naturais. As áreas de FPE e de FPNE localizam-se no município de Manicoré, Estado do Amazonas. Realizou-se o inventário utilizando o método de amostragem aleatória, em ambas as áreas. As amostragens foram executadas em dois níveis de inclusão de DAP. No nível I foram instaladas cinco parcelas de 100 x 100 m (1 ha), onde foram inventariadas todas as árvores com DAP > ou = 15 cm. No nível II, as parcelas do nível I foram divididas sistematicamente em subparcelas de 10 x 10 m (100 m²), tendo sido amostradas aleatoriamente cinco subparcelas por parcela do nível I, totalizando 2.500 m², onde foram inventariados todos os indivíduos (varejões) com 5,0 <= DAP < 15 cm. As análises dos danos decorrentes de causas naturais indicaram que na FPNE apenas 10% da vegetação adulta remanescente apresentou danos. Na FPE, os danos causados pelas operações de colheita florestal, incluindo-se o corte e o arraste de toras, totalizaram 29%. As modificações na estrutura diamétrica da FPE foram maiores nas maiores classes de DAP, em que, em geral, foram constatadas reduções de 27, 29 e 30%, respectivamente, no número de árvores (n/ha), na área basal (m²/ha) e no volume (m³/ha). Essa redução de estoque foi considerada normal, uma vez que a amostragem foi realizada imediatamente após a execução das operações de colheita florestal.

Helmet design to facilitate thermoneutrality during forest harvesting

The purpose of this investigation was to evaluate the ventilatory characteristics of vented and non-vented helmets for use in forestry harvesting operations. A ventilation index developed by Birnbaum and Crockford (1978) was used to determine the ventilation capacity of twelve helmets varying in design and presence, location, and dimension of vents. Helmets with top vents had higher ventilation indices than non-vented, side and side/top-vented helmets. Ten physically fit men participated in a maximal oxygen consumption test and four trials wearing a non-vented, round-side-vented, round-top-vented or rectangulartop-vented helmet. Trials simulated typical summer environmental conditions (28°C, 80% rh) and physiological work loads (40% V O 2 max) experienced during forest harvesting in New Zealand. The temperature and humidity under the helmet was typically lowest when the helmet with the largest vented area (288 mm 2) in the crown was worn, although physiological responses (temperatures at the tympanum, ear and scalp; humidity at the centre of the helmet) of the participants to wearing the helmets differed significantly during some rest periods only. Top-vented helmets (in this experiment measured 288 mm 2) should be worn to minimize temperature and humidity of the head during forest harvesting operations.

Health and Safety Issues and Perceptions of Forest Harvesting Contractors in Ireland

The aim of this study was to examine the extent and severity of accidents and long-term health problems, and to evaluate perceptions of health and safety issues among forest harvesting contractors and sub-contractors in Ireland. A postal questionnaire was distributed to 450 forest harvesting (sub)contractors with the co-operation of the Irish Forestry Contractors Association (IFCA) and Coillte Teoranta (the State Forestry Company, referred to as Coillte). The questionnaire was completed and returned by 61 respondents. The majority of these were chainsaw, harvester and forwarder operators. The occurrence of an accident (requiring medical attention) in the last three years was reported by two respondents, while long-term health problems were reported by 23 (40%) of the respondents. Results showed that long-term health problems were not significantly correlated to age or training level. The two work elements in forest harvesting operations that were found to be most hazardous were operating a chainsaw and machine maintenance. When asked about the perceived dangers in the industry and the obstacles to improvements, 59% of the respondents identified harvesting work as dangerous, while 62% described financial pressure as the main barrier to improvements in safety, followed by the pressure of work (39%) and a lack of adequate training (36%). Suggestions on ways to improve the overall health and safety situation within forest harvesting included improved training and safety education (45%) and reduced work pressure (36%).

Heart rate strain in cable hauler choker setters in New Zealand logging operations

This study examined the physical strain experienced by cable hauler choker setters, and the applicability of heart rate indices for measuring physical strain in commercial forest harvesting operations in New Zealand. The heart rate of four choker setters were recorded continuously throughout the working day and applied to heart rate indices. Based on the relative heart rate at work (%HRR), ratio of working heart rate to resting heart rate and 50% level indices, the mean working heart rate (HR w) of 106 bt. min −1 ±6.9 (mean±SD) placed choker setting in the moderate workload category. The specific tasks of line shifts (120.3±4.8 bt. min −1), hooking up drags (118.8±6.6 bt. min −1) and uphill travel (126.1±12.9 bt. min −1), imposed the most severe workloads on the choker setters. This research also demonstrated that heart rate indices could be used as an effective means of determining the physiological strain of subjects working in New Zealand's commercial forest harvesting operations.

Forest harvesting operations in South Africa

The author had the opportunity to spend the past year at the University of Stellenbosch, Faculty of Agricultural and Forestry Sciences, as the Chair of Forest Engineering. This article summarizes the forest harvesting situation in South Africa and reflects on some of the dilemmas that forest operations managers must contend with daily. Key words: South Africa, logging, harvesting, mechanization, appropriate technology

Soil compaction induced by careful logging in the claybelt region of northwestern Quebec (Canada)

Soil compaction induced by forest harvesting operations can reduce site productivity. Intensity, extent and persistence of soil compaction were assessed on fine- to medium- and coarse-textured soils. Severe compaction took place in the wheel track section of the skid trails. On fine- to medium-textured soils, half of the effects on the 0- to 10-cm and 10- to 20-cm mineral soil bulk densities (+11 and +8%) and half of the changes in the 10-cm depth soil strength (+69%) occurred in the course of the first two skidding cycles (cycle of half impact). On coarse soils, half of the effect on the 0- to 10-cm bulk density (+11%) occurred during the first three passes. Cycles of half impact for soil strength were 9, 14, 7 and 6 for the 2.5-, 5-, 10-, and 20-cm depths and corresponded to increases of 235, 402, 157 and 103% respectively. Compaction was more limited between track sections of trails. Six to twelve years following clearcutting on fine- to medium-textured soils, 0- to 10-cm soil bulk density was less in the skid trails than on the undisturbed sections of cutovers. Careful logging on moist, fine- to medium-textured soils is the safest way to limit the extent of soil compaction. On coarse-textured soils, spreading the traffic remains a valid option. Key words: Soil compaction, bulk density, soil strength, forest harvesting, careful logging