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European beech (Fagus sylvatica L.) forests in Central and Southern Italy are managed applying the shelterwood system. Prior to the regeneration cut, it is common to apply 2–3 thinning interventions, aiming to obtain mostly firewood, considering the low dimension and poor quality of the stems. These interventions are usually carried out by local forest enterprises relying on a low or medium level of mechanization (small‐scale forestry). In particular, the short wood system is applied, thus processing the logs to 1 m length and extracting them with forestry‐fitted farm tractors equipped with forwarding bins. Despite the large application of this harvesting system in the Mediterranean forestry, no information is available in the literature about its possible disturbance to the forest soil. To fulfill this knowledge gap, we developed the first assessment of soil physicochemical (bulk density, penetration resistance, shear resistance, organic matter content) and biological (soil microarthropods biodiversity evaluated with the QBS‐ar index, that is, an index based on the idea that high‐quality soils have more groups of microarthropods that are morphologically better adapted to the soil than low‐quality soils) properties for this kind of logging operation. In three case study areas in Central Italy, we applied an experimental design to evaluate separately the impacts related to the passage of the machine and that of the silvicultural treatment itself. We further applied linear mixed‐effect models to investigate the relationship between changes in soil physicochemical and biological properties. We found the effect of the silvicultural treatment to be negligible, but there was a significant alteration of the investigated parameters in the soil affected by the passage of the machine. Soil penetration and shear resistance doubled in the forwarding trails (0.25 MPa and 4.02 t m−2, respectively) in comparison with the other two experimental treatments (control area and soil not affected by the machine passage; about 0.12 MPa and 2.10 t m−2, respectively). Soil organic matter and soil microarthropod biodiversity (QBS‐ar index) were reduced by 25% in the forwarding trails (about 30% and 92 respectively) in comparison with the soil not affected by the machine passage (about 39% and about 130, respectively). Such significant disturbance, which occurred even if the applied machinery had lower weight in comparison to other alternatives (forwarders), is related to the high number of machine passes needed to extract the woody material with forwarding bins applying the short wood system. We found a significant relationship between soil compaction and soil organic matter removal and microarthropod biodiversity, with the latter which resulted significantly lower in more compacted and organic matter‐poor soils. We demonstrated that this small‐scale extraction system can have a negative effect on soil features in the short term. We therefore recommend the application of best management practices, for instance placing brush mats and logging residues, on the forwarding trails to limit the soil disturbance within the framework of small‐scale forestry. We further recommend a wider application of aerial harvesting systems, which generally have lower impacts to the soil. However, this could happen only after an extensive training program aimed to increase the knowledge and skills of local loggers about aerial harvesting systems. [ABSTRACT FROM AUTHOR]

The recovery of soil properties and the proper growth of natural tree regeneration are key elements for maintaining forest productivity after selective logging operations. This study was conducted on the soil properties and natural growth of two pioneer seedling species of alder and maple which were on skid trails in the mixed beech forests of northern Iran. To examine the long-term effects, we randomly selected six skid trails, with two replicates established for each of three time periods since last use (10, 20, and 30 years ago). Random plots 4 m × 10 m in size, three plots on each skid trail and six plots on areas without soil compaction (control), were selected. Measurements included the physical and chemical properties of the soil and the growth, and the architectural and qualitative characteristics of the seedlings. The results showed that all the soil properties of the 10- and 20-year-old skid trails were significantly different from the control area (except for the soil moisture in the 20-year-old skid trail). The 30-year-old skid trail showed values of other soil properties which were not significantly different from the control area, except for the amounts of organic matter and soil nitrogen, which was less than the control. The skid trails had a negative effect on all of the growth, qualitative, and architectural indices of seedlings. The characteristics of seedlings were related to soil characteristics and had the highest correlation with the soil penetration resistance (R-value from −0.41 to −0.63 for stem growth, p < 0.05; −0.57 to −0.90 for root growth, p < 0.01; and −0.76 to −0.86 for biomass, p < 0.01). The correlation coefficient between soil penetration resistance and the Dickson quality index of alder and maple seedlings was, respectively, −0.74 and −0.72, p < 0.01. The negative effect of soil compaction on root growth (−27.69% for alder seedlings and −28.08% for maple seedlings) was greater than on stem growth (−24.11% for alder seedlings and −16.27% for maple seedlings). The amount of growth, qualitative, and architectural indices of alder seedlings were higher than that of maple seedlings. Although alder is a better choice as compared to maple seedling in the initial year, the results of our study show that it is recommended to plant both alder and maple on skid trails after logging operations. [ABSTRACT FROM AUTHOR]

Logging operations change the forest environment by creating a heterogeneous canopy with a range of different microenvironments that differ mostly in light intensity and level of soil disturbance. In this study, the growth characteristics and architecture of beech (Fagus orientalis Lipsky) seedlings grown in three different microenvironments in terms of canopy and soil conditions were investigated. The experimental treatments (microenvironments) included skid trail (removal of canopy and compacted soil), winching corridor (natural canopy and compacted soil), felling gap (removal of canopy and natural soil), and comparison with the control area (canopy and soil in natural state). The results showed that the status of many growth and architectural indicators of seedlings is significantly less favorable than in the control area. These indicators include the length and biomass above and below ground, and the ratio of root length to stem length in the skid trails and winching corridors. The status of these indicators was, however, more favorable in felling gaps than in the control area. The seedling quality index decreased by −12.2% and −4.9% in skid trails and winching corridors, respectively, but increased by 2.4% in felling gaps compared to the control area. The growth characteristics and biomass of seedlings had a significant negative correlation (p < 0.01) with soil bulk density and penetration resistance and a significant positive correlation (p < 0.05) with soil porosity, moisture, and organic matter content. These results showed that the creation of a gap in the stand canopy due to the cutting of individual trees created a favorable micro-environment for the growth of seedlings, but the soil compaction caused by logging operations created an unfavorable micro-environment for these. Therefore, it is necessary to plan and execute the operation of extracting the cut trees in such a manner as to reduce the extent and severity of soil compaction with the goal of preserving and maintaining the stability of the forest ecosystem. [ABSTRACT FROM AUTHOR]

High-quality pellets are typically produced from coniferous sawdust. However, achieving comparable quality from alternative feedstocks, such as broadleaf wood, often necessitates pre-treatments or additives. Yet, within the framework of small-scale pellet production, local forest enterprises may lack the resources for such treatments and usually produce pellets from the whole trees, including branches, leaves and tops. This can have an impact on the quality of the pellets obtained in this manner. To be classified as high-quality pellets (A1 class), the specific features of the pellet must be higher or fall below the thresholds specified in the EN ISO 17225 standard. In this study, we developed an alternative statistical approach to evaluate pellet quality in comparison to the constant thresholds reported in the technical standard. We applied such an approach to evaluate the quality of pellets produced from the broadleaved species common in the Mediterranean forestry, including European beech (Fagus sylvatica L.), Turkey oak (Quercus cerris L.), Eucalyptus (clone Eucalyptus camaldulensis x C. bicostata), and Poplar clone AF6. In particular, we focused on three variables that are generally the most troublesome for the production of high-quality pellets from the broadleaved species, namely bulk density, ash content, and lower heating value. We found that the beech pellets showed satisfactory bulk density (average effect size of −1.2, with no statistical difference in comparison to the standard's threshold) and ash content (average effect size of about −5 and significantly lower than the standard's threshold), but the heating value was significantly lower than the threshold required by the standard (average effect size of about −3). Conversely, other investigated species exhibited notable deficiencies, with turkey oak pellets displaying acceptable heating values. We found a significant improvement in ash content and heating value with increasing stem age within the same species thus suggesting that material derived from thinning interventions might be preferable over coppice-derived biomass for high-quality pellet production. We suggest that future research on the topic should focus on investigating pellets produced from blends of beech and turkey oak biomass. We further recommend a wider application of the proposed statistical approach, considering that it is clear and easy to interpret, and allows for a statistical comparison of the obtained values against the requirements of the technical standard. [ABSTRACT FROM AUTHOR]

The aim of the present study was to elucidate the effects of soil compaction on the seedlings of two species of deciduous (Acer velutinum and Alnus subcordata) and evergreen trees (Pinus eldarica and Pinus nigra) in terms of above- and below-ground morphology in a greenhouse. Six soil compaction levels were applied: the lowest intensity (control), very low, low, moderate, heavy, and very heavy. The results showed that there were different effects according to the species. These effects were on lateral root length, stem diameter, leaf dry biomass, SSL (specific stem length), SRL (specific root length), LMR (leaf mass ratio), RMR (root mass ratio), SMR (stem mass ratio), and R/S (root-to-shoot ratio). The results showed that soil penetration resistance (SPR) had a significant effect on seedling variables such as lateral root length, stem diameter, leaf dry biomass, and SRL (p < 0.05). A. velutinum seedlings have the highest values of growth variables compared to three other species, followed by A. subcordata seedlings. The two evergreen species, Pinus eldarica and Pinus nigra, have the lowest values of these growth variables. It is worth noting that we found that deciduous species had enhanced growth up to a moderate compaction level (1.3 MPa), while the growth decreased at an SPR that was higher than this value. [ABSTRACT FROM AUTHOR]

Biochar has gained significant interest in the agroforestry sector, mainly because of its ability to improve soil quality and sequester carbon in the atmosphere. Among the feedstocks of possible use for biochar production is biomass, understood as products and residues of plant origin from agriculture and forestry. The quality of the biomass used for biochar production is important because the physicochemical characteristics of the final product depend on it. This review examines the use of biochar produced from forest wastes and its impact on agriculture, forest ecosystems and the environment in general. This work demonstrates that the use of biochar not only improves agricultural productivity and production, but also that the sustainable management of the environment and forests and contributes to forest fire risk mitigation. The authors, examining the physico-chemical properties of biochar produced by forest waste, noted that the most critical variable is the process (pyrolysis temperature, residence time and heating rate), but the type of biomass used as a raw material and the forest species used also have a significant impact in determining the characteristics of the final product. [ABSTRACT FROM AUTHOR]

The application of modern technologies to increase the overall sustainability of forest operations is known as precision forest harvesting. Precision forest harvesting can be a very powerful tool; however, it requires modern forest machinery, which is expensive. Given that most of the forest operators in the Mediterranean area are small-scale businesses, they do not have the resources to purchase costly equipment; thus, the application of precision forest harvesting is affected. Bearing this in mind, in this study, we aimed to test the accuracy of the GNSS receiver on which an innovative Information and Communication Technology (ICT) system developed to monitor small-scale forest operations is based. We tested the GNSS's accuracy by comparing the extraction routes recorded during coppicing interventions in two forest sites located in Central Italy with those obtained with a more high-performing GNSS receiver. We also used linear mixed-effects models (LMMs) to investigate the effects on the GNSS positioning error of topographic features, such as the slope, elevation, aspect and Topographic Position Index (TPI). We found that the average positioning error was about 2 m, with a maximum error of about 5 m. The LMMs showed that the investigated topographic features did not significantly affect the positioning error and that the GNSS accuracy was strongly related to the specific study area that we used as a random effect in the model (marginal coefficient of determination was about 0.13 and conditional coefficient of determination grew to about 0.59). As a consequence of the negligible canopy cover after coppicing, the tested GNSS receiver achieved satisfactory results. It could therefore be used as a visualising tool for a pre-planned extraction route network, allowing the operator to follow it on the GNSS receiver screen. However, these results are preliminary and should be further tested in more experimental sites and various operational conditions. [ABSTRACT FROM AUTHOR]

Among the various species of trees, black alder (Alnus glutinosa (L.) Gaertn.) is one of the most commonly used trees for the reforestation and restoration programs of degraded forestlands in the Hyrcanian forest, particularly in the skid trails. The effects of reforestation with black alder on the recovery of litter (thickness, C, N, C/N) and soil physicochemical, biochemical, biological, and microbial properties in the skid trails with three levels of compactions were examined over a 27‐year period. Results showed that the litter characteristics such as thickness, carbon (C), nitrogen (N), and C/N were at the highest level in low intensity traffic as compared to those of medium and frequent intensities. Results showed that the values of total porosity, macroporosity, aggregate stability, silt, and clay were at the lowest level in the natural stand. The highest values of soil pH, C, C/N ratio, and C storage were recorded under the skid trail with frequent machine passages. The restoration values of soil physical and chemical properties were significantly higher in the low level of machine traffic after a period of 27 years where black alder reforestation was performed on the skid trails, as compared to the medium and frequent machine traffic levels, as well as the undisturbed area. Black alder litter affected soil nitrogen and the maximum amounts of earthworm density and dry mass. This also includes fine root biomass. These data were recorded in the trails with low machine traffic as compared to those of medium and frequent traffic. The results clearly showed that black alder is effective in reaching the objectives of restoration programs, given that it promotes soil organic matter, builds up soil structure via root‐soil feedback, and improves the soil by creating a major source of nitrogen through enhancing the nitrogen cycle. [ABSTRACT FROM AUTHOR]

Fine roots are an important component of forest soil as they play a key role in fundamental processes like plant nutrition and water supply. As with all the features of forest soil, the compaction related to the forest operations and, in particular, to the wood extraction via ground‐based technologies could lead to a significant impact on the presence of fine roots in the soil affected by the passage of the machines. Considering the lack of a review, we used a meta‐analytic approach to synthesise effect sizes of ground‐based extraction technologies affecting the presence of fine roots in the soil, using a multivariate mixed‐effects meta‐analytic model. The obtained results revealed that the presence of fine roots in the soil affected by the passage of the machines was significantly reduced by both skidding (g = −1.23, 95%CI ‐1.87, −0.60) and forwarding (g = −1.37, 95%CI ‐2.01, −0.74). Due to the higher soil compaction caused by forwarding, this method had a marginally but statistically significant greater impact than skidding. We further confirmed the hypothesis that soil compaction and the presence of fine roots were strongly correlated, with the latter being greatly reduced in compacted soils characterised by higher bulk density. What is more, even more than 20 years after a harvesting intervention, the presence of fine roots was significantly lower in both strip roads (forwarding) and skid trails (skidding) as compared to areas which were not impacted by the machine passage. This shows that fine roots are particularly vulnerable to forest operations. On the other hand, the majority of the trails in the database used for the meta‐analysis were created in countries that favour the creation of a small number of widely used trails. Therefore, it would be scientifically valuable to do a comparative evaluation in various forestry contexts, such as in the Mediterranean area, where the development of the forest trails network is oriented on creating a large number of trails with low traffic volumes. Because machinery‐induced soil compaction is the major driver of the decrease in fine roots in skid trails and strip roads, both the application of best management practices as well as of a smarter planning of the trail network to limit soil compaction are strongly recommended. Both applications are highly recommended to be used in the planning phase and in the practical implementation of logging activities. [ABSTRACT FROM AUTHOR]

Ground-based skidding can lead to severe soil disturbance by increasing surface water flow and soil erosion. Organic mulches have been shown to be effective in contrasting this type of soil disturbance, although the cost/benefit aspect has yet to be studied. This study, by installing runoff sample plots, aims to elucidate the effects of litter (LM) and sawdust (SM) mulches with three application rates (litter: 7.6 Mg ha−1 LM7.6, 14.6 Mg ha−1 LM14.6, 22.5 Mg ha−1 LM22.5; sawdust: 5.3 Mg ha−1 SM5.3, 11.4 Mg ha−1 SM11.4, 16.7 Mg ha−1 SM16.7) on runoff, soil, and nutrient loss (nitrate and phosphate) in skid trails established in the Hyrcanian forest. The results were also compared to the undisturbed area (UND) and to an untreated skid trail (UNT). The results showed that both litter and sawdust mulch significantly decreased runoff, soil loss, and nitrate and phosphate loss. The values of runoff, runoff coefficient, soil loss, NO3, and PO4 were at the highest level in the untreated skid trails (UNTs). The runoff, runoff coefficient, soil loss, NO3, and PO4 gradually decreased as the application rate of both the litter (LM) and sawdust (SM) mulches increased. According to the results, it is possible to conclude that the mulch application rates of 7.6–14.6 Mg ha−1 and 5.3–11.4 Mg ha−1 for litter and sawdust mulch, respectively, can be applied to maintain soil and water conservation after logging operations on skid trails. The obtained findings can help to shape specific best-management practices for the implementation of sustainable forest operations in the context of the study area, by indicating suitable mulch types and application rates to decrease the negative effects of erosion. [ABSTRACT FROM AUTHOR]