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Rosewoods are among the most valuable traded hardwoods, and there is a significant illegal trade. From 2017 onwards the international trade in all species of Dalbergia rosewood is regulated through the Convention on International Trade in Endangered Species of Wild Fauna and Flora. I focus on two species of rosewood that occur in parts of Indonesia, Dalbergia latifolia and D. sissoo, to assess the extent of the illegal trade and to analyse geographical and temporal patterns of wildlife crime. Based on 67 seizure reports from 2014 to 2022 I show that (a) 117 logs of D. sissoo and 4,285 logs of D. latifolia were confiscated, (b) seizures occurred on the islands of Sumatra (16 seizures; 1,190 logs), Java (43; 1,780 logs), and Bali, Lombok, Sumbawa and Timor (8; 1,408 logs), (c) while there was an increase in the number of seizures per year, there were no seasonal differences in seizure activities. For 10% of the logs there was supporting evidence that they were taken from State managed forests and 18% was taken from conservation areas, thus causing more damage than just the removal of individual trees. Seizures in Indonesia over this period equals 0.12 ± 0.04% of the legal rosewood export. The illegal trade is dominated by Indonesians rather than foreign nationals and the direction of trade is towards Java from where > 95% will be exported to China. While policies are in place concerning rosewood seizures and stockpiling (including auctioning or destruction) in practise it is unclear where seized rosewood ends up. When used with caution, analysis of seizure data offers a valuable means to gain insights in illicit activities that normally remain hidden from view. [ABSTRACT FROM AUTHOR]

Deadwood is known to be an irreplaceable substrate for various groups of organisms but its importance for vascular plants is still unclear. To examine which deadwood characteristics promote its colonization by vascular plants and whether species can prefer this substrate to mineral soil (or vice versa), we used regression modeling and ordination methods to analyze an extensive data set of vegetation records from more than 1800 pieces of lying deadwood and 200 control plots on soil. Data were collected in four old-growth forest sites ranging from lowland alluvial to mountain spruce forests. Colonization of deadwood of all decay classes, including freshly fallen logs, was frequent at all study sites. The density of colonizers differed between deadwood species, increased with deadwood decomposition stage and was higher when deadwood was exposed to light. On average, about 40% of observed species showed a preference for either deadwood or soil substrate with preference for soil usually being more common. Species that preferred deadwood to soil were typically early successional species, while those with preference for soil were often hygrophytes or typical understorey species. Most species responded consistently to substrate across multiple sites. With its unique microsite conditions and specific composition of plant colonizers, we highlight the importance of deadwood for herb layer species composition. Deadwood retention should be encouraged not only in protected but also in commercial forests. [ABSTRACT FROM AUTHOR]

Efficient forest operations are essential for forest enterprises, who provide wood and numerous ecosystem services for the society. Important factors influencing the efficiency of forest operations, and thus the harvesting costs, are the level of mechanization, the harvesting method applied, the forest road network, and the training of the labourers. The cost of labour, i.e. salaries, is another important driver of harvesting costs. However, its effect on and relative importance for overall harvesting costs is poorly described in the scientific literature. Thus, this study aims to analyse the influence of labour costs in more detail, especially on the country-wide wood harvesting potentials. In addition, we aimed to cross-compare the effect of labour costs with the effect of switching to a more efficient harvesting method. For this purpose, we calculated timber harvesting costs with varying salaries for all sample plots of the Swiss National Forest Inventory (NFI) for both, the currently applied harvesting method recorded in the NFI, and the potential best suitable harvesting method. A 1% change in labour costs affects harvesting costs by 0.33–0.77%, depending on the harvesting method applied. The influence is larger for systems that involve a large share of motor-manual work and for cable-based methods. Changing labour costs by ± 30% affects the number of plots for which timber harvesting is economically feasible, by 5 to 15 percent points. The effect of switching from the current to the best suitable harvesting method is comparable to that of reducing labour costs by 15–30%. These results indicate that the efficiency of wood harvesting can be increased with further mechanization and does not require cutting salaries of forestry personnel. In that, our results may inform forestry planning and policy making at regional to national level. [ABSTRACT FROM AUTHOR]

In the Brazilian Amazon, logging is primarily restricted to the driest months of the year by law. Even so, the dry season in the humid tropics is susceptible to considerable rain events, with rain occurring monthly. Therefore, an experiment was established in unentered Central Amazonian old-growth forest to compare skid trail use in the wet season, when logging operations are not permitted, as well as in the dry season. This was done to investigate the differences in soil compaction for the season closed to logging versus the season open to logging. A randomized complete block design (RCBD) was utilized with three blocks composed of seven sub-blocks each, which contained a control, 1, 3 and 12 tractor cycles in both the wet and dry seasons. A Caterpillar track-type tractor model D6D was used for experimental skid trail establishment. Regardless of season the initial machine cycle caused the greatest increase in soil bulk density (BD) and penetration resistance (PR), as well as the greatest decrease in macroporosity. In fact, the initial dry season cycle caused more severe compaction than the wet season. Nevertheless, after 3 cycles, increases to BD and PR were similar for both seasons, with the end result after 12 cycles nearly identical. To the contrary, macroporosity was substantially reduced in the dry season versus the wet season. Overall, the site impacts were similar in both seasons. Thus, skidding operations could be permissible during the wet season with similar impacts caused in the dry season. [ABSTRACT FROM AUTHOR]

Assessing the financial, energy and emission levels associated with alternative harvesting prescriptions, techniques, and technologies is crucial to sustainable forest management. This study aims at developing an overall predictive system able to estimate productivity, fuel consumption and emissions for a set of different forest harvesting technologies as a function of stand characteristics, site conditions and silvicultural prescriptions. The system consists of two separate group of models, one for felling and processing, and the other for extraction. In the first model, six quantitative (DBH, tree volume, harvest, engine power, purchase price of the machine) and five qualitative independent variables (forest species, management, treatment, operation, type of machine, type of fuel) were considered. In the second model, four qualitative and six quantitative independent variables were applied. Both models have been trained on a large database of real field data using linear and nonlinear approaches based on artificial intelligence. The dataset was randomly separated into two subsets, one using for training the models and the other for validating them. The models reliably predicted fuel consumption (r = 0.84–0.95), energy emission and cost (r = 0.88–0.98), per hour and per hectare, and they were successfully validated. Despite being estimated from a heterogeneous input dataset, constituted by quantitative and qualitative variables, both models proved to be efficient, robust and generally representative. The input variables are intuitive and suitable for practical use by both entrepreneurs and policy makers at the institutional level. [ABSTRACT FROM AUTHOR]

Since the 1950s, the tree of heaven (Ailanthus altissima) has progressively invaded forests in southern Switzerland and is becoming a growing concern also north of the Alps. Recent studies have increased the understanding of the species' ecology, but its role in long-term stand dynamics remains uncertain. Therefore, we simulated the long-term dynamics of unmanaged and managed forest stands in southern and northern Switzerland under current and future climate conditions (RCP8.5) using the forest gap model ForClim. Our results indicate that A. altissima will increase its presence in the short term (< 100 yrs), but does not gain dominance in the long term (> 200 yrs), confirming its pioneer character. Timber harvesting led to an increasing share of A. altissima compared to unmanaged stands. Overall, our findings suggest that in the long run, a competitive displacement of native dominant species by A. altissima appears unlikely, with the exception of drought-prone sites under strong climate change. Furthermore, our findings underline the importance of the frequency and intensity of forest management for the long-term abundance of A. altissima in forest stands. [ABSTRACT FROM AUTHOR]

Radical changes are necessary to address challenges related to global warming and pollution. Ever-tightening emission standards for combustion engines have already led to a drastic reduction in the amount of harmful gas and matter emitted. Drivetrain hybridization and electrification, which are becoming increasingly popular in all sectors, are two additional ways to achieve that goal. However, within the forestry sector most of the equipments still rely on conventional mechanic or hydraulic drivetrains. An example of this is tower yarders, the workhorse of the alpine logging industry. This work simulates the duty cycle and energy flow of tower yarders in logging operations, both with conventional diesel–hydraulic configuration and a proposed hybrid configuration. The objective is to determine the potential of hybridized drivetrains for tower yarder applications. Detailed models are developed to describe the cable-based extraction of timber and tower yarder internal processes. Extensive simulations were performed to determine force, power and energy components during the harvesting operation for both the diesel–hydraulic and hybrid drivetrains. Results confirm the large potential of the hybrid configuration for efficiency improvement and emission reduction, with estimated fuel savings of 45% and 63% in the uphill and downhill configurations, respectively. Extensive sensitivity analysis further demonstrates that the hybrid concept remains effective across a wide range of cable setup and transport characteristics. This confirms the large potential of electrified drivetrains, especially in the presence of very dynamic duty cycles, as is the case in cable-based logging equipment. [ABSTRACT FROM AUTHOR]

The aim of this study was to measure and model the fuel consumption of cut-to-length (CTL) logging machinery in cutting and forwarding under Nordic harvesting conditions, and to clarify which factors had the greatest effect on the fuel consumption. In addition, the total annual fuel consumption and CO2eq emissions were calculated for CTL logging operations in Finland in 2020. The data were collected during a long-term follow-up study on the fuel consumption of harvesters and forwarders conducted between March 2018 and April 2019. The fuel consumption data were obtained from a total of 16 harvesters and 13 forwarders equipped with digital flow metres featuring an accuracy of ± 1% of the fuel volume measured. The engine power of the forest machines explained most of the hour-based fuel consumption. Correspondingly, the harvesting conditions of the forest stand best explained the cubic-metre-based fuel consumption. The fuel consumption of CTL logging operations (cutting and forwarding) averaged 1.4 L m−3 in final felling, and 3.1 and 2.2 L m−3 in first and later thinning, respectively. There was a large variation in the cubic-metre-based fuel consumption between individual machines, both for harvesters and forwarders. The total calculated fuel consumption in Finnish CTL operations in 2020 was 126.6 million L, with the calculated CO2eq emissions totalling 334,209 t (i.e. 5.7 kg m−3). Several measures to accelerate fuel and energy efficiency and reduce CO2eq emissions in CTL logging operations are discussed in the paper. [ABSTRACT FROM AUTHOR]

Deadwood is a key component of forest ecosystems, but there is limited information on how it influences forest soils. Moreover, studies on the effect of thinning-derived deadwood logs on forest soil properties are lacking. This study aimed to investigate the impact of thinning-derived deadwood logs on the soil chemical and microbial properties of a managed spruce forest on a loamy sand Podzol in Bavaria, Germany, after about 15 years. Deadwood increased the soil organic carbon contents by 59% and 56% at 0–4 cm and 8–12 cm depths, respectively. Under deadwood, the soil dissolved organic carbon and carbon to nitrogen ratio increased by 66% and 15% at 0–4 cm depth and by 55% and 28% at 8–12 cm depth, respectively. Deadwood also induced 71% and 92% higher microbial biomass carbon, 106% and 125% higher microbial biomass nitrogen, and 136% and 44% higher β-glucosidase activity in the soil at 0–4 cm and 8–12 cm depths, respectively. Many of the measured variables significantly correlated with soil organic carbon suggesting that deadwood modified the soil biochemical processes by altering soil carbon storage. Our results indicate the potential of thinned spruce deadwood logs to sequester carbon and improve the fertility of Podzol soils. This could be associated with the slow decay rate of spruce deadwood logs and low biological activity of Podzols that promote the accumulation of soil carbon. We propose that leaving thinning-derived deadwood on the forest floor can support soil and forest sustainability as well as carbon sequestration. [ABSTRACT FROM AUTHOR]

Knowledge of the patterns in the degradation of cellulose and lignin in decaying logs under different climatic conditions is necessary to understand the carbon cycling in forest ecosystems since cellulose and lignin are the dominant carbon fractions in decaying logs. However, the effects of the environmental heterogeneity by variation in canopy cover on the degradation of cellulose and lignin in decaying logs remain unknown. To evaluate the effect of forest gaps, we measured the concentration and mass loss of cellulose and lignin in experimentally exposed decaying logs in gaps, at the edge of gaps, and under the closed canopy during a four-year in situ log incubation experiment in a subalpine Minjiang fir (Abies faxoniana) forest on the eastern Qinghai-Tibet Plateau, China. We found the lowest cellulose concentration in gaps for all wood tissues, while we observed the opposite for lignin except for bark. Based on the linear relationship between cellulose and lignin concentrations, the rate of lignin enrichment in bark and heartwood was slowest in gaps and fastest under closed canopy, while in sapwood gaps had almost no influence. The mass loss of cellulose was highest in gaps for all wood tissues in any decay classes. The gap effect on lignin mass loss in decaying logs showed high variability with wood tissues and decay classes. Our results show that forest gaps accelerate the degradation of cellulose and lignin during the decomposition of logs by increasing cellulose mass loss and slowing lignin enrichment. The observed gap effects were mediated by wood tissues but not by decay classes. [ABSTRACT FROM AUTHOR]

Small tree size represents a main challenge for single-tree handling techniques and caps harvesting productivity in short rotation poplar (SRP) plantations. That challenge is best met by a shift towards mass-handling. Chainflail delimbing is one of the best solutions for multi-tree processing, but commercially available equipment is often too heavy and expensive for European operations. Therefore, an Italian company developed a compact chainflail delimber-debarker (CFDD) specifically designed for small-scale SRP. The machine was tested in Western Slovakia in early March 2022. The test included a five-days endurance trial and a controlled experiment on 16 carefully measured wood piles representing "strong" and "weak" trees, i.e. trees with a mean diameter at breast height (DBH) of 12 and 10 cm, respectively. The endurance trial was quite successful since no mechanical problems were recorded during the five-days period. Delimbing and crosscutting quality were as good as those obtained with a standard processor head, while log yield was generally better, averaging 42% and 68% for the "weak" and the "strong" trees, respectively. Productivity was on a par with the alternative cut-to-length technology options and can be significantly increased once the prototype will be further developed. In general, the new compact CFDD may become the best option for handling the small trees offered by underdeveloped SRP plantations, which cannot be efficiently harvested with the cut-to-length system. [ABSTRACT FROM AUTHOR]

Changes in vegetation and forest floor are among the factors affecting the variability of ecological indicators of soil organic and mineral layers. Therefore, the present study was conducted to examine the effect of forest floor on soil microbial properties and enzyme activities of skid trails after skidding operations. A total of 216 soil samples were taken from three litter treatments (B; beech, B-H; beech-hornbeam, B-H-O; mixed beech with maple and alder species) on skid trails that were each assigned to three time periods (6, 10 and 20 years after harvesting). All combinations were replicated three times. 20-years since harvest, the values of TP, N, available nutrients, NH4+, NO3−, fulvic and humic acid were highest in the B-H-O treatment and then B-H > B. In contrast, BD, C and C/N ratio were at the lowest level in the B-H-O treatment followed by B-H < B. The highest value of soil microbial characteristics and enzyme activity belonged to B-H-O treatment followed by > B-H > B and 20-years since harvest followed by > 10 years > 6 years. Values of soil microbial respiration (15%), microbial biomass carbon (8.7%), microbial biomass nitrogen (15.4%), urease (10.2%), acid phosphatase (4.4%), arylsulfatase (8.8%) and invertase (6.9%) in the B-H-O treatment measured 20 years after harvesting were less than the values of the undisturbed area. According to the results, as an ecological response to soil disturbance after skidding operations in skid trails, planting a mixture of trees with proper litter quality improves soil properties. [ABSTRACT FROM AUTHOR]

The aim of the work was to quantify the mass of logging residues (branches and tops; t yr−1 dry matter, DM) for energy generation starting from Forest Management Plans (FMP) data. The methodology was applied to public stands of an Italian district (area: 3.60 × 104 ha; period: 2009–2018). Compared to the previous preliminary analysis, the potentially available residues were computed considering forest accessibility and road traversability, by combining FMPs data with a geographic information system (GIS). New issues that were assessed here were: (i) representation of stands consisting of multiple disconnected parts; (ii) calculation of producible residues by using different values of biomass expansion factors (Scenario 1, S1; Scenario 2, S2). The potentially available residues computed for the analyzed period were used to quantify the current sustainable supply. Then, the potentially generated heat (thermal energy, TE; GJ yr−1) and electricity (EE; GJ yr−1), and the potentially avoided CO2 emissions into the atmosphere (EM; t yr−1 CO2) related to the final combustion process were computed by assuming that the current supply of residues was used as woodchips in a local centralized heating plant currently operating. For both S1 and S2, the large difference between the potentially producible and the potentially available residues demonstrated that geodata are essential for reliable estimations. Moreover, as the required information for the GIS analysis can be easily found in databases made available by forestry authorities, the proposed approach can be applied also to other areas; this could be helpful to support local decision-makers in defining sustainable practices for residues recovery. [ABSTRACT FROM AUTHOR]

Climate-adaptive forest management aims to sustain the provision of multiple forest ecosystem services and biodiversity (ESB). However, it remains largely unknown how changes in adaptive silvicultural interventions affect trade-offs and synergies among ESB in the long term. We used a simulation-based sensitivity analysis to evaluate popular adaptive forest management interventions in representative Swiss low- to mid-elevation beech- and spruce-dominated forest stands. We predicted stand development across the twenty-first century using a novel empirical and temperature-sensitive single-tree forest stand simulator in a fully crossed experimental design to analyse the effects of (1) planting mixtures of Douglas-fir, oak and silver fir, (2) thinning intensity, and (3) harvesting intensity on timber production, carbon storage and biodiversity under three climate scenarios. Simulation results were evaluated in terms of multiple ESB provision, trade-offs and synergies, and individual effects of the adaptive interventions. Timber production increased on average by 45% in scenarios that included tree planting. Tree planting led to pronounced synergies among all ESBs towards the end of the twenty-first century. Increasing the thinning and harvesting intensity affected ESB provision negatively. Our simulations indicated a temperature-driven increase in growth in beech- (+ 12.5%) and spruce-dominated stands (+ 3.7%), but could not account for drought effects on forest dynamics. Our study demonstrates the advantages of multi-scenario sensitivity analysis that enables quantifying effect sizes and directions of management impacts. We showed that admixing new tree species is promising to enhance future ESB provision and synergies among them. These results support strategic decision making in forestry. [ABSTRACT FROM AUTHOR]

Information on terrain conditions is a prerequisite for planning environmentally and economically sustainable forest harvesting operations that avoid negative impact on soils. Current soil data are coarse, and collecting such data with traditional methods is expensive. Forest harvesters can be harnessed to estimate the rolling resistance coefficient (μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document}), which is a proxy for forest trafficability. Using spatio-temporal data on engine power used, speed travelled, and machine inclination, μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document} can be computed for harvest areas. This study describes an extensive, high-resolution data on μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document} collected in a boreal forest landscape in Southern Finland during the non-frost period of 2021, covering roughly 50 km of harvester routes. We report improvements in removing some of the previous restrictions on calculating μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document} on steeper slopes, enabling the calculation within a -10∘\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$-10^{\circ }$$\end{document} to +10∘\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$+10^{\circ }$$\end{document}  slope range with a speed range of 0.6–1.2 ms-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-1}$$\end{document}. We characterise the variation in μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document} both between and within 11 test sites harvested during the April-August period. The site mean μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document} varies from ∼\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\sim$$\end{document} 0.14 to 0.19 and shows significant differences between the sites. Using simulations of the hydrological state of the soil and open spatial data on forest and topography, we identify features that best explain the extremes of μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document} within the sites. Several wetness-related indices, such as the depth-to-water index with varying thresholds, explain the μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document} extremes, while biomass-related stand attributes indirectly explain these through their linkage to site and soil characteristics. Obtaining μRR\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\mu _{RR}$$\end{document} from actual operational data extends the capabilities of large-scale harvester-based data collection and paves the way for building data-driven models for trafficability prediction. [ABSTRACT FROM AUTHOR]

Swing yarders in running skyline configuration using either grapples or chokers represent the most common configuration for cable yarding in coastal British Columbia. In this context, whole-tree logging and short work cycles lead to heavy and repeated loads applied to the trees and stumps when used as anchors for the rigging cables. Moreover, increased harvesting of second-growth forest stands leads to the unavailability of large and safe trees, thus introducing new challenges to identify suitable anchors and potentially increases safety risks of cable yarding operations.The present study aimed to collect evidence of the mechanical response provided by anchors for typical cable yarders used in second-growth harvesting in coastal British Columbia, and test the suitability of innovative techniques for the stability assessment based on the relationship between the anchor root-plate rotations and the related applied tensile forces. A conspicuous dataset could be derived from all the surveys, storing anchor rotations from a total of 1522 work cycles of which 1224 work cycles included also tensions measurements. The methodological approach was proven effective for monitoring different rigging configurations giving proof that repeated loading affects the stability of a tree/stump which can rapidly change over few hours of active yarding operations. Acquired data proved also that comparing theoretical failure limits with anchor rotations could be a valid approach however a considerable amount of species-specific data from tree pulling tests is required. [ABSTRACT FROM AUTHOR]

Subject to overexploitation in the past centuries, the Atlantic Forest is subject to very rigorous protection rules. However, the law is a controversial issue since landowners are not compensated for the limited choice of land use possibilities. We believe that, alternatively to a general timber harvest ban, sustainable forest management of the Atlantic Forest has the potential to generate income for the landowners while sustaining important ecological functions of the forest. Such choice would require better understanding of the potential effects of timber harvesting on the forest ecosystem and on species composition and succession over time. In this context, we assessed the harvesting impact of a conventional harvesting method (CM) and compared it to an alternative harvesting method (AM) in three different stands (stands A, B and C) of a secondary forest fragment in southern Brazil. Results from three comprehensive forest inventories over a period of two years were used to assess the timber harvesting impact. Measurements of species composition (i.e., number of species, life form, ecological group), forest structure (i.e., density, basal area, DBH, volume) and saplings density formed the basis of the impact assessment. The inventories were carried out before, immediately after and two years after harvesting. Intensities of damage on remnant trees immediately after harvesting and two years after harvesting were also measured. Before harvesting, a total of 114 tree species (trees, tree fern and palm tree) belonging to 49 families were identified in the study site's three research stands. Palm trees and secondary species, such as Euterpe edulis, represented the majority of recruited individuals (DBH ≥ 5 cm) two years after harvesting. However, new saplings (DBH ≤ 5 cm) after two years were mainly pioneer woody tree species, such as Cecropia glaziovii and Schizolobium parahyba. On average, AM reduced damage to saplings by 5%. Most of the damages caused by CM were moderate to severe, while AM caused light to moderate damages. Binary logistic regression indicated dependency of the mortality rates on the independent variables "stand, stem and leaning damages." On the other hand, the recovery rates of damaged trees were dependent on crown, stem and leaning damages. Therefore, two years after harvesting a higher mortality rate of low-dimensional trees was observed in stands with high density of smaller trees and high density of improvement felling. Although crown damages were not related to mortality rates, high intensity of crown damages reduced recovery rates over time. [ABSTRACT FROM AUTHOR]

The study investigated the effects of forest residue extraction on tree growth and base cations concentrations in soil water under different climatic conditions in Sweden. For this purpose, the dynamic model ForSAFE was used to compare the effects of whole-tree harvesting and stem harvesting on tree biomass and the soil solution over time at 6 different forest sites. The study confirmed the results from experimental sites showing a temporary reduction of base cation concentration in the soil solution for a period of 20–30 years after whole-tree harvesting. The model showed that this was mainly caused by the reduced inputs of organic material after residue extraction and thereby reduced nutrient mineralisation in the soil. The model results also showed that whole-tree harvesting can affect tree growth at nitrogen-poor forest sites, such as the ones in northern Sweden, due to the decrease of nitrogen availability after residue removal. Possible ways of reducing this impact could be to compensate the losses with fertilisation or extract residue without foliage in areas of Sweden with low nitrogen deposition. The study highlighted the need to better understand the medium- and long-term effects of whole-tree harvesting on tree growth, since the results suggested that reduced tree growth after whole-tree harvesting could be only temporary. However, these results do not account for prolonged extraction of forest residues that could progressively deplete nutrient pools and lead to permanent effects on tree growth. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

As a generalization, harvested timber is extracted from forests either as trees or stems by skidders or as logs by forwarders. Coupled with harvesters, forwarders team up to form cut-to-length (CTL) systems that are often perceived to be more modern than full-tree (FT) and tree-length (TL) systems, based on feller bunchers and skidders. As a result, CTL machinery has been extensively studied in Europe, while little information is available on FT and TL machinery and especially skidders. Using all available documentation, and relying on national experts, this paper reports on a survey of skidders used for timber extraction in Europe. The survey identified a total of 8370 skidders, whereby the authors accept this to be a lower limit with potentially many other units not identified through the survey. Also, while the focus of the survey was purpose-built skidders, many modified farm tractors are also used to extract tree-length material. Of the 8370 skidders, 5500 were found in the Central European region with Germany and France dominating the market. The survey also indicated an overall low level of replacement, with fewer than 5% being from new sales annually. Although CTL systems are a dominant harvesting option, this survey has shown that skidders continue to be a common and viable extraction method. Given their high level of extraction efficiency that is often restricted by a limit of clear-fell operations, further large-scale damaging storm events in Europe may offer a clear opportunity for their expansion. [ABSTRACT FROM AUTHOR]

Small tree size represents the main challenge when designing a cost-effective harvesting system for European short-rotation plantations. This challenge is further complicated by the need to obtain 4-m logs for high-end products, which rules out the possibility of deploying whole-tree chipping. Both challenges can be met through mass or multi-tree handling (MTH), which must begin at the time of felling and continue uninterrupted along the whole supply chain. The objective was to: (1) gauge the productivity and the cost of CTL harvesting applied to these plantations; (2) assess log yield and capacity to match dimensional specifications; (3) determine if MTH applied to CTL technology offers a real benefit compared with conventional single-tree handling. The authors conducted a time study using a block design with a two-machine cut-to-length harvesting system (i.e. harvester and forwarder) in single- and multi-tree handling operations on the clear cutting of a hybrid poplar plantation in Poland, as well as we manually measured the produced volumes of the study. Higher productivity (+ 8%) was achieved under the multi-stem handling mode. The MTH system proved capable of containing harvesting costs below € 15 per green ton, while fulfilling set timber quality requirements in terms of value recovery and log quality specifications. A new, software-based, MTH system is recommended to be used in short-rotation poplar plantation for logs and biomass harvesting. When the coppicing season is over, the system can be deployed for the conventional thinning operations. [ABSTRACT FROM AUTHOR]

Recent studies show that several tree species are spreading to higher latitudes and elevations due to climate change. European beech, presently dominating from the colline to the subalpine vegetation belt, is already present in upper montane subalpine forests and has a high potential to further advance to higher elevations in European mountain forests, where the temperature is predicted to further increase in the near future. Although essential for adaptive silviculture, it remains unknown whether the upward shift of beech could be assisted when it is mixed with Norway spruce or silver fir compared with mono-specific stands, as the species interactions under such conditions are hardly known. In this study, we posed the general hypotheses that the growth depending on age of European beech in mountain forests was similar in mono-specific and mixed-species stands and remained stable over time and space in the last two centuries. The scrutiny of these hypotheses was based on increment coring of 1240 dominant beech trees in 45 plots in mono-specific stands of beech and in 46 mixed mountain forests. We found that (i) on average, mean tree diameter increased linearly with age. The age trend was linear in both forest types, but the slope of the age–growth relationship was higher in mono-specific than in mixed mountain forests. (ii) Beech growth in mono-specific stands was stronger reduced with increasing elevation than that in mixed-species stands. (iii) Beech growth in mono-specific stands was on average higher than beech growth in mixed stands. However, at elevations > 1200 m, growth of beech in mixed stands was higher than that in mono-specific stands. Differences in the growth patterns among elevation zones are less pronounced now than in the past, in both mono-specific and mixed stands. As the higher and longer persisting growth rates extend the flexibility of suitable ages or size for tree harvest and removal, the longer-lasting growth may be of special relevance for multi-aged silviculture concepts. On top of their function for structure and habitat improvement, the remaining old trees may grow more in mass and value than assumed so far. [ABSTRACT FROM AUTHOR]

In cut-to-length logging, the harvester operator adjusts the bucking in accordance with visible defects on processed stems. Some of the defects, such as a sweep on the bottom of the stem, decrease the yield and quality of sawn products and are difficult for the operator to notice. Detecting the defects with improved sensors would support the operator in his qualitative decision-making and increase value recovery of logging. Predicting the maximum bow height of the bottom log in Norway spruce (Picea abies (L.) Karst.) with log end face image and stem taper was investigated with two modelling approaches. A total of 101 stems were selected from five clear-cut stands in southern Finland. The stems were crosscut and taper measured, and the butt ends of the bottom logs were photographed. The stem diameter, out-of-roundness, and pith eccentricity were measured from the images while the max. bow height was measured by a 3D log scanner at a sawmill. The bottom logs with an eccentric pith had higher max. bow height. In addition, a highly conical bottom part of the stem was more common on the bottom logs with a large max. bow height. Applying both log end face image and stem taper measurements gave the best model fit and detection accuracy (76%) for bottom logs with a large max. bow height. The results indicate that the log end face image and stem taper measurements can be utilised to aid harvester operator in deciding an optimised length for logs according to the bow height. [ABSTRACT FROM AUTHOR]

In mechanized logging operations, interactions between the forest machines and their operators, forest resources and environmental conditions are multifold and not easily detected. However, increased computational resources and sensing capabilities of the forest machines together with extensive forest inventory data enable modeling of such relationships, leading eventually to better planning of the operations, better assistance for the forest machine operators, and increased efficiency of timber harvesting. In this study, both forest machine fieldbus data and forest inventory data were acquired extensively. The forest inventory data, acquired nationwide, was clustered to categorize general tree and soil types in Finland. The found forest categories were applied when the harvester fieldbus data, collected from the forest operations in the North Karelia region with two similar harvesters, was analyzed. When the performance of the machine and the operator, namely the fuel consumption and log production, is studied individually for each forest cluster, the impact of working environment no longer masks the causes based on the machine or the operator, thus making the observations from separate forest locations comparable. The study observed statistically significant differences in fuel consumption between the most general tree and soil clusters as well as between the harvester-operator units. The modeling approach applied, based on multivariate linear regression, finds such reasons for the differences that have clear interpretation from machine setup or operator working style perspective, and thus offers a feasible method for assisting the operators in improving their working practices and thus the overall performance specifically at forest of given type. [ABSTRACT FROM AUTHOR]

Climate change makes it necessary to re-evaluate the erosion potential of forest infrastructure. We used the Forest Service WEPP interfaces (FS WEPP) to compare soil erosion potentials of two competing logging practices in steep terrain in the Northern Black Forest, Germany: (1) Felling with harvesters and logging with forwarders in slope line with optional traction supporting winches. (2) Felling by chainsaw, logging with a cable winch, and further transport of logs via forest dirt roads. After forest harvest we measured erosion, runoff, and DOC concentration in runoff from 50 m sections of two machine tracks, two cable tracks, and a dirt road for 2 years. The erosion measurements were used to validate FS WEPP management options and a regionally adjusted CLIGEN input file. With these parameterizations we compared the erosion potential of the two practices on subcatchment scale by modeling return periods and total sediment export with FS WEPP. Model results show that logging operations with heavy machinery in slope line are less prone to soil erosion than logging operations including winch logging and additional dirt roads. The former produces less sediment in its worst-case configuration than the latter in its most moderate configuration by a factor of two. Model results also show that erosion prevention benefits from long periods of 10 years between two harvests. [ABSTRACT FROM AUTHOR]

Forest soil conditions can be affected by ground-based harvesting; the degree of impact depends upon management factors, location of stands, soil, and topographical conditions. The present study predicted the area and extent of the disturbance of forest soil using soil data collected from 39 ground-based working areas. Random sampling was used to lay out 351 circular sample plots, each with a radius 10 m and located within 39 working areas, before the beginning of logging operations. Data regarding local conditions including stand characteristics, terrains, physical and mechanical properties of the soil, and extraction method was collected and used as predictor variables. Soil compaction, displacement, and rutting were defined as the response variables and were measured post-harvest. The results showed that E-value, cone index, and extracted volume had the most effect on the area of compaction. The lowest soil displacement was recorded at gentle slope and extracted volume of less than 5 m3/ha in clay–loam soil. Rutting of clay soil was most effectively predicted using E-value, slope, and extracted volume. A geospatial-explicit predictive model of soil disturbance was developed using a generalized additive model by implementation of generalized regression analysis and spatial prediction. Land types susceptible to detrimental soil disturbance during ground-based harvest operations were depicted geospatially by GIS. The models can be used as a decision support tool to predict forest harvesting impacts on soil properties. [ABSTRACT FROM AUTHOR]

A grapple-saw is a low-cost implement, consisting of a hydraulic chainsaw mounted on the frame of a standard log grapple. Grapple-saws are generally installed on forwarders, loaders or modified excavators and are used for crosscutting whole trees or delimbed stems, often as part of a more complex work task such as pre-bunching, loading or stacking. The study analyzed eight different commercial operations where trees were processed with grapple-saws, instead of dedicated cut-to-length processors. All machines in the study were mounted on excavators, but were used under a wide range of stand types and work conditions, although most of the study stands were managed as coppice. Work productivity was determined with time study techniques, which covered the processing of 1800 trees for a total time of 73 h. Productivity ranged between 0.8 and 13 dry t per productive machine hour or between 0.7 and 11 dry t per scheduled machine hour, depending on whether delays (i.e., interruptions of productive work) were excluded or included, respectively. Regression analysis allowed modeling productivity as a function of significant variables, such as tree size, machine type and processing quality. In particular, processing quality was defined as "coarse" when conducted according to lax size and form specifications, or "high-quality" when size and form specifications were strict. The productivity of coarse processing rapidly increased with tree size until the optimum value of 0.3 dry t per tree, and then it slowly declined. The same trend was found for high-quality processing, but in this case optimum tree size was 0.6 dry t per tree. Productivity was higher for landing site work, cold deck operations and coarse processing into tree sections. A dedicated cut-to-length processor is a better choice for matching tight log product specifications, while the grapple-saw is best for handling firewood and chip wood. A grapple-saw is a low-investment piece of equipment for mechanizing small-scale operations, to the benefits of increased productivity, lower processing cost and improved worker safety. [ABSTRACT FROM AUTHOR]

A comparative study was conducted in the second commercial thinning of a 12-year-old slash pine (Pinus elliottii Engelm.) plantation in South Africa. The goal of the study was to compare semi-mechanized tree-length harvesting with fully mechanized cut-to-length (CTL harvesting) in terms of: compliance with silvicultural prescriptions, value and volume recovery, productivity, cost and residual stand damage. The two systems were tested on 32 adjacent plots with a mean surface of 4000 m2 each. Plots were randomly allocated to the two treatments, so that each treatment was replicated 16 times. The experiment consisted of a classic time study, followed by the visual inspection of all plots for determining damage frequency and severity. While mechanization allowed a dramatic (tenfold) increase in worker productivity, it also resulted in a proportional increase in team cost, which offset the large efficiency benefit and ended up with both methods incurring similar production cost (180-200 ZAR m3). However, mechanized CTL harvesting resulted in a significant reduction in residual stand damage frequency (from 5.2 to 2.9%) and severity (28% smaller wounds). Mechanized CTL is preferable, because it can reduce the frequency and severity of residual stand damage. In social terms, however, mechanization reduces employment potential but promotes job quality, while conventional harvesting solutions can employ many more people, but offer low-paid, tiresome and potentially hazardous jobs. [ABSTRACT FROM AUTHOR]

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). [ABSTRACT FROM AUTHOR]

In 1849, Martin Faustmann published a formula for determining the claim on an insurer if fallow woodland has been definitely destroyed. His evaluation is based on an even-aged plantation and a given logging time. The calculation has later been used to derive an allegedly optimal rotation period which nowadays predominates in forestry economics. In fact, the utilized objective function does not engender the superior harvesting strategy but the highest compensation for the damaged ground. However, Faustmann’s approach can be generalized in order to maximize the expected value of a timber company’s total assets comprising soil and existing stumpage. The best felling practice turns out to be the principle of maximum sustainable yield already decreed by Austria’s emperor Joseph II in 1788. As a result, the difference between profitability and efficiency is resolved. [ABSTRACT FROM AUTHOR]

We used national scenario analyses to examine the effects of fertilization, use of improved regeneration material and ditch network maintenance (DNM), both separately and simultaneously, on timber production of Finnish forests under the current climate. We also analyzed how the area of artificial regeneration, forest fertilization, and DNM developed in different management and harvesting intensity scenarios. The initial data were obtained from the 11th National Forest Inventory of Finland, excluding protected forests. Four sets of even-flow harvesting scenarios with annual timber harvest targets of 60, 70, 80, and 90 million m3 were developed for 90-year simulation period. Use of improved material in artificial forest regeneration was assumed to result in 10% higher diameter and height increment compared to naturally regenerated seedlings. Sub-xeric pine-dominated and mesic spruce-dominated sites were fertilized, and 40% of drained peatlands were maintenance-ditched when they fulfilled a set of predetermined criteria for temperature sum, stand basal area, and mean tree diameter. As a result, when fertilization, improved regeneration material, and DNM were all used, the mean annual volume increment over the 90-year simulation period increased by 3.4-5.4 million m3 depending on harvesting intensity. The maximum sustainable harvest of timber would be almost 80 million m3 yr−1. The simulated fertilization area was about four times larger than the presently fertilized area, and the simulated DNM area was about the same as the current. Fertilization gave the largest additional 90-year volume increment and the DNM the smallest when they were used separately. The use of improved regeneration material gave the largest additional volume increment in southern Finland and fertilization in central and northern Finland. [ABSTRACT FROM AUTHOR]

Lime-trees (Tilia begonifolia Stev.) have countless ecological and economical values in the northern forests of Iran. Bole wounds on residual trees are commonly caused by logging. The healing ability of bole wounds and the effect of bole wounds on diameter growth in lime-trees were assessed in a natural mixed uneven-age stand. The susceptibility to decay in relation to the wound severity was also evaluated. Condition and location of lime-trees before and after selective logging were determined through systematic plot sampling. The position of each lime-tree was identified on a topographical map using the global positioning system. After 10 years from wound occurrence, tree and wound characteristics were also re-measured. Overall, 68 stems (9.7 stem ha−1) of lime-trees were found in the sampled area, 25 stems (36.8%) were damaged in the form of bole wound, and 43 stems (63.2%) were undamaged. Statistical differences between wounded or non-wounded lime-trees in terms of diameter and height were not found. Most of the wounds occurred at the height of < 1 m; the average wound size was 370.5 cm2. Wound severity was related to wound size and wound position. Wound width healing rate was 6.2 mm year−1. The wound shape was found to be a healing factor as the healing rate by width was higher than that by length. Healed wounds were only 12, 60% of bole wounds resulted in decay. Diameter growth of wounded trees was 43.5% lower than undamaged trees. The average annual diameter growth decreased by increasing wound severity. The results indicated the lime-tree is a very sensitive species to damage caused by logging (bole wound). Single-tree selection cutting needs more careful logging operations to reduce damage on residual lime-trees in order to safeguard this species, valuable in ecologic and economic terms. [ABSTRACT FROM AUTHOR]

The correct calculation equation and unit expression were exhibited as follows: HT ht Graph where mass loss (mg cm SP -3 sp ) is the cellulose or lignin mass losses in decaying logs after the decomposition of four years; I Concentration i SB 2013 sb and I Concentration i SB 2017 sb are the cellulose or lignin concentrations (%) of decaying logs in 2013 and 2017, respectively; I Density i SB 2013 sb and I Density i SB 2017 sb are the density (g cm SP -3 sp ) of decaying logs in 2013 and 2017, respectively; and 10 is the conversion coefficient of the unit. We mistakenly presented the calculation equation and unit expression of cellulose and lignin mass losses in decaying logs. [Extracted from the article]

Trees harvested in cuttings are usually partitioned into timber assortments, for instance, saw logs, poles and pulpwood logs. Since different assortments have different prices, the way in which harvested stems are crosscut affects the incomes of the forest landowner. Optimal crosscutting aims at maximizing the total value of the assortments obtained from the stems. Although forest research has developed several algorithms for optimal crosscutting, it has rarely been included in the optimization of stand management. Treatment prescriptions are often based on analyses in which the value of harvested trees is calculated without considering the whole set of timber price categories and without simulating the crosscutting of harvested trees. This may lead to biased conclusions about optimal stand management. This study proposed a fast and flexible method for optimizing the crosscutting of harvested trees in the context of stand management optimization. The method employs simulated annealing to find the optimal combination of log lengths, separately for each harvested tree. The results calculated for case study stands suggest that optimal crosscutting leads to longer rotation lengths than obtained in analyses where the values of harvested trees are predicted with more simple methods. Optimal crosscutting increases the incomes of forest landowner and the proportions of the most valuable saw log assortments. The proportion of harvested pulpwood decreases. [ABSTRACT FROM AUTHOR]

The presence of coarse woody debris in forests is an important naturalness criterion as well as a biodiversity indicator. Decaying logs provide habitat for many organisms including vascular plants. The aims of this study are to describe the colonization of decaying logs by vascular plants in a lowland alluvial forest and to assess the impact of fallen logs on the biodiversity of the herb layer. We investigated 493 logs in the Ranšpurk National Nature Reserve in southern Moravia. For each log, we recorded species of vascular plants rooting on its surface. Decaying logs were characterized by their dimensions, woody species and decay class. Vascular plants rooted on 279 surveyed logs. Decaying logs were colonized by 79 species of vascular plants. Terrain relief was found to be a significant factor for colonizing species. Our study did not find any significant spatial pattern of colonized logs with regard to the distribution of vascular plants, intensity of colonization or the ecological demands of colonizers. The colonization of lying logs by vascular plants was significantly influenced by the species of logs, their surface area and decay class. Species composition of vascular plants on decaying logs and that on mineral soil were significantly different. Demonstrably higher frequencies of Dryopteris carthusiana and Impatiens parviflora were found on decaying logs. The presence of decaying logs and the microsites they create is important for total forest biodiversity including the diversity of vascular plants. We recommend increasing the proportion of decaying logs even in commercial forests. [ABSTRACT FROM AUTHOR]

Forest harvesting operations may have a significant impact on soil physical properties by reducing its porosity and organic functions. Soil variations, in particular bulk density and total porosity, caused by external perturbations as soil becomes compacted due to machinery passes, can lead to changes in biogeochemical cycles that have consequences on soil ecosystems. This study investigated how the impact of forest operations and the elapsed time from harvest can influence: (1) the physical-chemical characteristics of soil and (2) the nitrogen-fixing and nitrifying microbial communities. The study area is located inside the Regional Park of Migliarino, San Rossore, Massaciuccoli (Pisa, Italy). In the study area, the soil has been classified as recent sands with sandy loam texture and slightly calcareous (USDA Soil Taxonomy classification). Soil samples were collected in patchy cut areas (strip cut) of Pinus pinea stand that was harvested in two steps: half area in 2006 and the rest in 2011. Soil samples were collected also in a control area (not harvested) with similar stand and soil characteristics. Statistical analysis was preceded by a test of normality (Kolmogorov-Smirnov test) and a variance homogeneity test (Levene's test). Considering the dependence of the variables studied (physical and chemical soil characteristics), a MANOVA test and a post hoc Tukey HSD test were applied to determine statistical difference among the three treatments: harvested 2006, harvested 2011 and not harvested. The results did not indicate significant variations to the parameters of shear and penetration resistance, though soil bulk density and total porosity were significantly altered in the short period since forestry operations occurred. These physical changes induced qualitative (presence/absence and number of species) and quantitative (abundance and spatial evenness of the species) variations in the nitrogen-fixing and nitrifying microbial communities. [ABSTRACT FROM AUTHOR]

Loss of canopy cover by forest harvesting generally increases the average surface runoff volume and sediment. Selective cutting (single and group selection method) is the most usual forest harvesting method in the Hyrcanian forests in the north of Iran. The purpose of this study is to find the effect of selective logging technique on the hydrological behavior of runoff and sediment in the Kheyrud forests located in northern Iran over 1 year. Four treatments were implemented: natural forest without harvesting (C), forest with selective harvesting (H) and area without canopy cover (WC) and skid trail (S). Three types of data were measured in each plot including soil chemical and physical properties, runoff and sediment load after each rainfall. The results indicate significant differences ( P ≤ 0.05) in runoff generation and sediment production with respect to the treatments cover. The runoff in all treatments showed relatively similar response to rainfall, while the highest runoff and sediment were observed in skid trails, and the area without canopy cover (1.13 and 0.62 mm, and 1.2 and 0.51 g m), averagely. In contrast, the natural forest without harvesting and the forest with selective harvesting treatments exhibited the lowest amounts of runoff (0.2 and 0.44 mm) and sediment (0.1 and 0.17 g m), averagely. Implementation of low logging technique was useful to control the effects of logging on the runoff and sediment yield. [ABSTRACT FROM AUTHOR]

Pinus pinaster (maritime pine) is widely planted in the Mediterranean Basin. Maritime pine forests' carbon stocks are dynamic because of the effect of wildfires and timber activities. Management practices offer an opportunity to mitigate climate change via increasing carbon storage in various ecosystems. In this work, we quantified carbon pools in P. pinaster forests in relation to fire occurrence and different post-fire salvage logging techniques. For this, we studied an area in northern Portugal where different parts had burned zero, one and four times during the last three decades. Following the last fire in 2012, two salvage logging treatments were carried out: (1) typical logging where all logs and tree biomass were removed and (2) conservation logging where burned tree branches were left in piles and log extraction was restricted to specific extraction trails. We assessed the carbon stocks for the aboveground and belowground compartments, taking into account their different components (vegetation, litter, roots and soil organic carbon). Our main findings were, firstly, that recurrent fires can be catastrophic in terms of carbon sequestration if the overstory dominated by P. pinaster does not regenerate after fire (2.4 times less). Secondly, soil organic carbon constituted an important carbon pool, being the most important when pines are eliminated due to recurrent fires with short intervals (90-95 %). Finally, the conservation technique applied here, leaving piles of branches on the soil surface, would be a suitable measure to increase carbon storage, at least in the short term, but might interfere with the recruitment of the pine stand. [ABSTRACT FROM AUTHOR]

Global competition in timber market leads to intensive mechanization of harvesting processes. Consequently heavy equipment is needed, which induces tremendous soil stresses, resulting in severe compaction and degradation of top- and subsoils, especially under moist conditions. Under these circumstances, it is still doubtful that natural processes are able to regenerate the impairments of a harmed forest soil. To test this hypothesis, a long-term field plot has been established in 2003 in Rhineland-Palatinate (Western Germany) on a silty clay loam Cambisol, combined with a measurement of the initial effects of mechanized timber logging on soil properties. Therefore, harvesting operations with a conventional heavy wood-loaded forwarder (Ponsse Caribou; total mass: 22 tons; maximum wheel load: 3.9 tons) were simulated to carry out two treatments with different driving intensities (1 pass, 5 passes). In 2013, analyses were reiterated (focusing on soil physical properties) to estimate the recovery status after a 10 year time span. The results reveal that the structural deformations associated with harmful effects on topsoil and subsoil, caused by wheeling, are still present. A slight regeneration can be considered for the low passing frequency, whereas the higher trafficked forest soil seems to be irreversibly damaged. It is to be expected that these adverse effects will never be fully recovered by natural regeneration. [ABSTRACT FROM AUTHOR]

This study determined the biomass retention effects and the technical-financial performance of alternative harvesting practices, applied to mountain sites. The two alternatives were: whole-tree (WT) and tree-length (TL) harvesting. Five cable yarding sites were selected from a larger pool of available sales, and on each site two adjacent and parallel cable corridors were set up, using the same base equipment and crew. For each of the 10 corridors (i.e. 5 sites × 2 corridors), the following data were recorded: biomass retention, product output, time and fuel inputs. Opting for TL harvesting resulted in a large (66 %) and significant increase in biomass retention, which may prove attractive where intensified biomass removal may jeopardize soil fertility and biodiversity. TL harvesting also resulted in a moderate increase (13 %) of total harvesting cost. Furthermore, TL harvesting required 30 % more labour input than WT, which may represent a disadvantage when forest labour is scarce. The increased labour use in TL harvesting occurs mainly at the stump site, where accident risk is highest. For all these reasons, managers should take their decision very carefully and opt out of more efficient WT harvesting only when the risk derived from increased biomass removal is quite severe. [ABSTRACT FROM AUTHOR]