Full Tree System Research Articles

Logging Residue Assessment in Salvage Logging Areas

Salvage logging operations often occur after large disturbances and usually leave behind a substantial quantity of residues, which is fundamental for maintaining soil fertility and facilitating ecosystem dynamics. This study aims to estimate the amount of logging residues following salvage operations categorized by two wood harvesting systems: Cut-To-Length (CTL) and Full-Tree System (FT). Logging residues in the harvested areas were sampled using linear transects and the data collected were divided into classes based on diameter. The quantity of residues was estimated using the Brown method for Fine Wood Debris (FWD) and the Van Wagner method for Coarse Wood Debris (CWD). Furthermore, the carbon and nutrient content associated with logging residues were also determined, considering their interaction with the soil organic layer. Overall, a higher quantity of FWD was detected in the sites cleared with the FT system and a higher quantity of CWD in the sites logged with the CTL system. Differences could be observed for all three years and systems considered, but only the third year reported statistically significant results (p<0.01). The soil and residue chemical analysis for carbon and nutrient contents revealed a high amount of carbon stored in a potential layer of 10 cm of soil (up to 85 Mg·C·ha-1), while only up to 15 Mg·C·ha-1 for the woody material.

Exposure to Occupational Noise

Physical agent noise can be considered one of the main disturbances that compromise the occupational health of self-propelled forest machine operators. We evaluated whether occupational noise levels emitted by self-propelled forest machines employed in the full tree system are in accordance with both the National Institute for Occupational Safety and Health and ISO 1999:2013 standards, while also proposing mitigating measures aimed at protecting the operators hearing. Seventeen operators, who performed wood harvesting operations in Eucalyptus forests in Brazil, were analyzed. Noise levels were collected in a daily shift of eight hours as recommended by the Acoustics – Determination of occupational noise exposure - Engineering method for full-day measurements (ISO 9612:2009). The standards adopted for the evaluation were the exposure action value of 80 dBA and the exposure limit of 85 dBA based on the National Institute for Occupational Safety and Health – NIOSH and on Acoustics – Estimation of noise-induced hearing loss (ISO 1999:2013) Directive 2003/10/EC. The operators were arranged in homogeneous groups according to the Acoustics recommendation – Determination of occupational noise exposure - Engineering method for full-day measurements (ISO 9612:2009), classified by the operations of felling, skidding of tree bundles and bucking. The results showed that 17 self-propelled forest machines exceeded the exposure action value of 80 dBA, of which 10 machines exceeded the exposure limit of 85 dBA. It was concluded that the levels of occupational noise emitted by self-propelled forest machines used in the full tree system are higher than those recommended by both standards, National Institute for Occupational Safety and Health and ISO 1999:2013. Therefore, the allocation of self-propelled forest machines to homogeneous groups allows inferring mitigation actions that protect operators' hearing. The correct use of hearing protectors during the daily workday provides hearing protection for operators in mechanized wood harvesting. Adoption of actions such as maintenance of cabin seals and mechanical components, breaks for fatigue relief, reduction of daily working hours and rotation of operators in different self-propelled forest machines can mitigate the damage to the occupational health of operators.

GRAPPLE SAW’S OPERATING CONDITIONS INFLUENCE ON THE PRODUCTIVITY AND COST OF PROCESSING FELLED TREES

In the full-tree system, one of the self-propelled forest machines used is the grapple saw, which uses mechanical force to delimbing and crosscutting stems, commonly in processing yards or on the sides of forest roads. Thus, several factors can influence the machine's effective productivity, and consequently, the production costs. Hence, the objective was to analyze the influence of the slope of the land on the productivity and production costs of the grapple saw under different operational conditions. The study was carried out in a forested area, in which there were clonal forests of Eucalyptus urograndis. The processing felled trees operation was performed with a grapple saw capable of accumulating and cutting the 0.85 m² tree bundles in two operating conditions. For the production forecast, the time study was applied, associating it to the volume of drawn wood and the effective work time, accordingly, it was possible to estimate the production cost of the grapple saw. The results allowed to conclude that the effective hourly productivity and the production cost of the log tracing are associated with the slope of the land.

Technical-Economic Analysis of Grapple Saw

The processing of Eucalyptus logs is a stage that follows the full tree system in mechanized forest harvesting, commonly performed by grapple saw. Therefore, this activity presents some associated uncertainties, especially regarding technical and silvicultural factors that can affect productivity and production costs. To get around this problem, Monte Carlo simulation can be applied, or rather a technique that allows to measure the probabilities of values from factors that are under conditions of uncertainties, to which probability distributions are attributed. The objective of this study was to apply the Monte Carlo method for determining the probabilistic technical-economical coefficients of log processing using two different grapple saw models. Field data were obtained from an area of forest planted with Eucalyptus, located in the State of São Paulo, Brazil. For the technical analysis, the time study protocol was applied by the method of continuous reading of the operational cycle elements, which resulted in production. As for the estimated cost of programmed hour, the applied methods were recommended by the Food and Agriculture Organization of the United Nations. The incorporation of the uncertainties was carried out by applying the Monte Carlo simulation method, by which 100,000 random values were generated. The results showed that the crane empty movement is the operational element that most impacts the total time for processing the logs; the variables that most influence the productivity are specific to each grapple saw model; the difference of USD 0.04 m3 in production costs was observed between processors with gripping area of 0.58 m2 and 0.85 m2. The Monte Carlo method proved to be an applicable tool for mechanized wood harvesting for presenting a range of probability of occurrences for the operational elements and for the production cost.

Soil and forest regeneration after different extraction methods in coppice forests

Coppice is considered the oldest form of sustainable forest management in the Mediterranean area. Generally, it produces rapidly woody biomass and environmental benefits. This research was implemented through an experimental design based on two steps: analyzing the impact of silvicultural treatment (coppice with standards) and logging on forest soil and tree regeneration. It included the soil and regeneration recovery capacity of forests managed as coppice related to different logging systems and treatments applied over a six-year period. The findings demonstrated that tree species regeneration composition was not affected by silvicultural treatment and only slightly by harvesting system. Instead, the physical, chemical and biological soil features were only marginally affected by the silvicultural treatment applied, but strongly impacted by harvesting operations, with clear differences between the systems. The least damaging harvesting system was TLS (Tree Length System) followed by FTS (Full Tree System) and SWS (Short Wood System) that showed a more intense impact. This trend started only six months after harvesting and continued for more than 36 months post-harvesting in a lesser dynamic. The recovery of coppicing was almost complete 36 months after harvesting, without substantial differences between logging systems. Recovery from logging showed a clear positive trend, but 52 months after harvesting only the TLS area had completely recovered. For FTS and SWS, recovery occurred but was very weak.

Ground-based harvesting operations of Pinus taeda affects structure and pore functioning of clay and sandy clay soils

Intense mechanization during forest harvesting and timber extraction degrades soil structure and affects pore functioning, but no studies have clearly distinguished the response of composition and functional soil properties to pine harvest in a subtropical environment. This paper describes the effect of mechanized harvesting of Pinus taeda L. on compaction and pore functioning of two subtropical Alfisols intensively used for commercial forest production in southern Brazil. The study was conducted in a 17-year old commercial forest of P. taeda on clay and sandy clay Hapludalf soils. Soil conditions tested were a control, i.e., before harvesting (BH); after tree felling (AF) in the full tree system; after timber dragging with one skidder pass (A1P); after timber dragging with three skidder passes (A3P); and after timber removal from stocking yard (TY). We evaluated composition (bulk density, degree-of-compactness, total porosity, and macroporosity) and functional (saturated hydraulic conductivity, precompression stress, compressibility coefficient, and penetration resistance) soil properties. The results show the upper soil layer is the most vulnerable to compaction, which significantly impairs pore functioning. Nevertheless, machine wheeling may affect subsurface layers (down to at least 0.40 m, as tested herein) depending on soil type, moisture and structure. Three passes of the skidder resulted in greatest degree-of-compactness, high bulk density, low macroporosity (below the critical level), reduced hydraulic conductivity (nearly water impermeable), and increased resistance to penetration (above the critical limit of 2 MPa). Pine harvest residues (9.8–15.6 Mg ha−1, corresponding to 7.3–8.2 cm height) were insufficient to dissipate stress applied by skidder intense wheeling. We show planning of harvesting activities must consider reducing traffic intensity and/or establishing permanent traffic routes to ensure minimum damage on forest soils, particularly on their functional soil properties.

Roundwood and bioenergy production from forestry: Environmental impact assessment considering different logging systems

The aim of this paper is to analyse the environmental performances of three different extraction systems for forestry considering three different scenarios concerning the valorisation of forest residuals are analysed.The compared tree extraction systems are characterised by felling and processing performed with chainsaw and three different extraction methods: i) by farm tractor equipped with a winch; ii) by skidder and iii) by cable crane. The “Full Tree System” was adopted for all the felling sites; trees were felled and transported to roadside with branches and top intact. For wood chips produced from branches and tops, different scenarios were considered: heat and electricity generation and substitution of wood-chip production.To evaluate the environmental performance the Life Cycle Assessment (LCA) approach was applied. The selected functional unit (FU) is 1 m3 of roundwood; the system boundary involves all the operations carried out in forestry (felling, bunching, extraction, processing, chipping of forest residuals), the transport of the produced wood chips and all the related inputs and emissions. A comparison with previously carried out studies in similar geographic areas were performed.The study's outcomes show how, the environmental results among the different logging systems are not univocal and the best logging system depends on the considered impact category. Though cable yarder is recognised as an extraction method able of reducing the physical impacts on residual stand (wounding) and soil (disturbance and compaction), for 10 of the 12 impact categories evaluated in this study, achieves the worst performances. The logging systems in which the extraction is performed using the tractor and the skidder show the best performance for 6 of the 12 evaluated impact categories. Finally, regarding wood residues utilisation and the impact of particulate matter formation, the energetic valorisation of wood chips does not involve any benefit but involves a worsening of the environmental performances due to wood combustion emissions.

Stand damage when harvesting timber using a tractor for extraction

Abstract Damage to the remaining stand is an unavoidable consequence of thinning operations. The different machines used for timber extraction differ in the level of damage of trees they cause, mainly through wounds to the bark and cambium which can make a substantial impact on the remaining trees. Three different methods of timber harvesting with a chainsaw were analyzed: the short wood system (SWS), the long wood system (LWS) and the full tree system (FTS) in which an agricultural tractor is used for timber extracting. All systems were analyzed in stands containing three different age classes: 2nd (21-40 years), 3rd (41-60 years) and 4th (61-80 years). The level of damage to the remaining stand was assessed considering the percentage of trees exhibiting wounds (scratched bark and/or damage to the cambium) to calculate an index of stand damage (WDI) which incorporated the volume of harvested timber per hectare. The SWS produced the lowest damage to trees in stands of all age classes: average 5%, with the less damage in the oldest stand. After using the LWS, 9% of trees were wounded; in this method there was no statistical difference in frequency of wounding across all the analyzed stands. The highest level of damage was incurred after the FTS, causing 11% of trees to be injured. In stands of the 2nd age class, the method of timber harvesting had no statistically significant effect on the amount of wounding endured. The WDI was lowest in SWS: 0.08, higher in LWS: 0.15 and the highest, 0.23, when FTS was applied.

Characterization of Woodchips for Energy from Forestry and Agroforestry Production

We set out to determine the particle-size distribution, the fiber, the bark and the leaves content, the heating value, the CNH and the ash content of a wide sample of wood chips, collected from 10 forestry and 10 agroforestry production sources. This sampling focused on two main production types: forestry (Full Tree System—FTS—and logging residues—LR) and agroforestry (Short Rotation Coppice—SRC). For the forestry production wood chips from coniferous and broadleaf species were considered. For the agroforestry production wood chips from poplar plantations were examined (different clones with two different harvesting intervals). Overall, we collected 400 samples. Particle size distribution was determined with an automatic screening device on 200 samples. The higher heating value was determined on 200 subsamples using an adiabatic bomb calorimeter. The CNH and the ash content was ascertained on another 200 subsamples. FTS and SRC (with three year old sprouts) offered the best quality, with high fiber content (71%–80%), favorable particle-size distribution and good energetic parameters. On the contrary, both logging residues and SRC (with two year old sprouts) presented a high bark content (18%–27%) and occasionally a mediocre particle-size distribution, being often too rich in fines (6%–12%), but the energetic parameters are in the normal range.

Machinery-induced soil compaction in thinning two pine stands in central Italy

Thinning is a crucial practice in forest management. There is, however, a dearth of studies that focus on the effects of thinning carried out by modern heavy machinery on the physical properties of soil. We studied the consequences of thinning in two pine forests in Central Italy. The “full tree system” (FTS) to convert the whole biomass into chips was applied in both cases, in one case by manual felling in the other using a harvester. Different mass tractors were used to bunch and bring the trees to the landing. We investigated the behaviour of soil in terms of bulk density, total porosity, aggregate stability, penetration and shear resistances, which are good indicators of physical soil quality. Results show that thinning dramatically changed soil properties, depending on the method employed to fell trees and move them along the skid trails or on the whole logging area. In particular, the penetration resistance of soil increased by about 50% and shear resistance by almost 40%, hence confirming that care and surveillance are necessary during thinning to prevent reducing soil quality and, consequently, forest productivity.

DETERMINATION OF THE FOREST ROAD NETWORK INFLUENCE ON THE SUPPLY CHAIN FOR FIREWOOD PRODUCTION BY DISCRETE EVENT SIMULATION

In this study a Discrete-event simulation (D-es) has been developed to analyze the wood supply chain for firewood production in a mountain area in North-eastern Italy. The D-es is applied in the modeling of extraction (Full Tree System), processing of roundwood into wood assortments (cross-cut and sorting), offroad and on-road transport. In order to estimate the productivity functions and parameters, field studies were conducted to gather data about the different operations linked in the model. Also a GIS network analysis was developed to integrate the spatial information onthe covered distance to the D-es model for each of the supposed Scenarios. The results indicats that an increment of 5 m ha<sup>-1</sup> of the forest road network could significantly increase the productivity of the wood supply chain up to 2%.

DETERMINATION OF THE FOREST ROAD NETWORK INFLUENCE ON THE SUPPLY CHAIN FOR FIREWOOD PRODUCTION BY DISCRETE EVENT SIMULATION

In this study a Discrete-event simulation (D-es) has been developed to analyze the wood supply chain for firewood production in a mountain area in North-eastern Italy. The D-es is applied in the modeling of extraction (Full Tree System), processing of roundwood into wood assortments (cross-cut and sorting), offroad and on-road transport. In order to estimate the productivity functions and parameters, field studies were conducted to gather data about the different operations linked in the model. Also a GIS network analysis was developed to integrate the spatial information onthe covered distance to the D-es model for each of the supposed Scenarios. The results indicats that an increment of 5 m ha-1 of the forest road network could significantly increase the productivity of the wood supply chain up to 2%.

Analisi della filiera di biomassa legnosa proveniente da interventi di diradamento: un caso di studio in una pineta dell’Italia centrale

Thinning is an essential practice in Mediterranean pine forests management but is rarely applied because of the high harvesting costs. The new market of bioenergy products could give a profit to wood biomass harvesting activities, though the drawbacks of elevated supply chain costs, related to technical problems and lack of knowledge about the wood quality have to be overcome in advance. This study analyzed technical, economic, energy and environmental factors of a pine stand thinning in Central Italy, where collected biomass was directed to energy, in order to give a decisional support to reach economical profitability and environmental sustainability in thinning practices. The introduction of Full Tree System maximized the recovery of available biomass, full tree chipping produced material with Heating Value superior than single tree components. The use of a felling frame in motor-manual felling in comparison with the traditional chainsaw reduced operator effort, increasing the number of felled trees per hour, when the stump diameter remained under 15 cm. The energy wood supply chain is not sustainable from an economic point of view, the profitability could be reached only acting on suggested technical levers and particularly reducing costs of hauling operation. The estimation of output/input energy ratio in the supply chain underlined the feasibility of thinning practices for energy. The assessment of CO2 emissions confirmed the environmental sustainability of biomass supply chain in energy when compared to traditional fossil fuels. Study conclusions provide the guidelines for thinning treatment in Mediterranean pine stands, in order to reach environmental and economic sustainability of these practices.

ANALISI ENERGETICA DI CANTIERI DI MECCANIZZAZIONE LEGGERA PER L’UTILIZZAZIONE DI UN CEDUO DI EUCALIPTO

The work was turned near Crotone (KR), in a 20 year-old plantation of Eucalyptus occidentalis Endl. positioned in hill zones, with average slope next to 27%. The utilisation system was the Full Tree System (FTS). The felling on the six yards has been done by chainsaw and the first coppice bunching was manual. fts 1, 2 - The extraction has been done by one drum forest winch applied to the three point hitch of a wheeled farm tractor forest version. fts 3, 4 - The extraction has been done by two drums forest winch, applied to the three point hitch of a wheeled farm tractor forest version. fts 5,6 - The extraction has been done by light tower yarder powered by one drum forest winch applied to the three point hitch of a wheeled farm tractor forest version. fts 1, 3 and 5 - At the landing the coppice have been processed by chainsaw in 2 meters length trunks. The slash accumulated and the trunks staked manually. fts 2, 4 and 6 - At the landing the coppice have been chipped by drum chipper with manual feed. The machine was a tractor powered chipper. At the landing the wood has been differentiated in two types. The type from the yards “fts 1,3,5” were 2 meters length trunks and the other type from the yards “fts 2,4,6” were chips for energy production. For the 2 meters length trunks the transport has been done by truck with 16 t of load capacity, and hydraulic crane. This material at the staple will be chipping by drum chipper with autonomous engine and mechanical feed. The chips transport will be done by truck with 17 t of load capacity. From the working times analysis and the wood quantitative obtained we studied the energy balance in the yards. We used the GER (Goss Energy Requirement) method. From the results obtained, the best work methodology seems to be that of full trees chipping directly at the landing and the chips transport at the staple. For the bunching and the extraction the best productivity result is given from the tractor with one drum forest winch. Considering the energy balance the yard that guarantees the greater efficiency is the “fts 4”, where has been employed for the extraction the tractor with two drums forest winch. The mechanization typology that supplied the better energy efficiency is that of the yards “fts 2,4 and 6” where the full trees has been chipped to the landing.