Forests produce an array of forest ecosystem services (Patterson and Coelho, 2009; Ciccarese et al., 2012; Miura et al., 2015; Vauhkonen and Ruotsalainen, 2017), but also, like in other sectors, causes negative environmental impact (Lundström et al., 2018). Research on the environmental impacts of the forestry sector is often limited to the negative effects of harvesting on the ecosystem (Martin et al., 2015; Kļaviņš et al., 2019; Ugawa et al., 2020). In terms of the magnitude of the environmental impact of the forestry sector, assessment often only focuses on certain aspects, such as biodiversity (Michelsen et al., 2012; Seedre et al., 2018), water (Allen and Chapman, 2001; Brown et al., 2007; Sundnes et al., 2020), soil (Piirainen et al., 2015), and air emissions (Virbickas and Galickaja, 2017).

Life Cycle Assessment (LCA) is among the methodologies utilized in environmental accounting, alongside Environmental Input–Output Analysis, Ecological Footprinting, Carbon Footprinting, and Ecological Cost (Patterson et al., 2017). These methodologies rely on input–output analysis and assess adverse environmental effects within the physical realm, among other aspects (Hayati et al., 2013; Latan et al., 2018; Burritt et al., 2019). A holistic view can be expected when applying the Life Cycle Assessment (LCA) method. However, its use on the forestry sector is connected to a number of methodological problems along with the risk of misapplication (Heinimann, 2012). Because, unlike the industry sector, forestry operates in a natural environment that is characterized by a complex set of internal and external ecosystem links. The function of this ecological system and its resilience guarantee the fulfillment of an array of ecosystem services that are important to human beings (Stohr, 2013). Ecosystem services provided by forests do not only include timber production, but also water management, soil conservation, climate, biodiversity conservation, hunting, forest fruit picking, and last but not least, recreational and spiritual services. From this point of view, the very definition of the scope of the study in the context of the LCA method is already complex, not to mention that the different forest functions may significantly interact (Sacchelli and Bernetti, 2019). For instance, monoculture timber production forests can have a negative impact on biodiversity and on the fulfillment of many other services, such as water, esthetic, recreation value and erosion control (Felton et al., 2016; Wan et al., 2017). Similarly, the timber-production ecosystem service of forests can be negatively affected by, for example, excessive of game animals for hunting (Ward and Williams, 2020), overabundant forest fruit picking, and intensive forest tourism (Price, 1987; Font and Tribe, 2000) can destruct the quantity and quality of woody tree regeneration.

Among the most common methodological problems in LCA is wrong understanding and inclusion processes of the silvicultural and harvesting into the product system. From an LCA perspective it is not about the “production” stage, but the raw material excavation stage, in this case, excavation of biotic raw material. Incorrect understanding and inclusion of the silviculture and logging processes within the life cycle stages then naturally entails an incorrectly defined functional unit. We often encounter a functional unit defined at the raw material excavation stage as 1 ha, 1 m3, or 1 t of timber (Bosner et al., 2012; Ferro et al., 2018). The problem is that it is not a functional unit, but only a declared unit, because at this stage a functional unit cannot be defined. Some studies include seed collection and subsequent operations up to the harvesting of timber, while others start with the felling of mature trees (Klein et al., 2015). Additionally, due to the length of rotation (100 years in this study), there is also a problem with the primary data collection (Sahoo et al., 2019). They often tend to be replaced by so-called secondary data, i.e., data from literature. This practice leads to a simplistic and often erroneous application of the LCA method. The shortcomings often reflect the fact that the LCA method has been primarily concerned with the assessment of industrial systems since its inception. The methodology should therefore be complemented by procedures related to living systems, and in particular by appropriate impact categories, or at least characterization factors, within the existing ones, to reflect the issues of human activity associated with living ecosystems.

These reasons led to the development of an improved approach from LCA. evaluating the environmental impacts of forestry activities in the Czech Republic. This methodology aims to provide a standardized framework for such assessments by prioritizing the collection of primary data over reliance on secondary sources, which would be a model methodological procedure for assessing the environmental impacts of the forestry sector throughout the Czech Republic. The first part of the methodology described in this article concerns forest production services. The methodology defines the scope of the study to avoid inaccuracies and methodological errors on the part of the LCA study developers regarding the determination of the appropriate reference unit, the scope of the system, the method of collection, and the quality of the data. It follows from our practical experience and literature research.

This paper aims to assess the environmental impacts of the forestry sector in the entire value chain corresponding to silviculture and harvesting, using the LCA for assessing the environmental impact of the forestry sector. Unlike the approach to LCA in the forestry sector in other publications (Heinimann, 2012; Klein et al., 2015; Đuka et al., 2017), our methodological approach focuses mainly on the qualitative aspect of primary data collection. The data are as detailed as possible, based on long-term research in forest typology, forest management planning, economics, standardization, and forestry sector technology. The validation of the proposed methodology is based on concrete data obtained at a company’s accounting statements. The paper also presents the findings of an environmental impact assessment conducted on three forest management scenarios, conducted at the scale corresponding to silviculture and harvesting. These scenarios were developed using the methodology outlined in the study. The methodology and findings in this study also serve as the basis of future research focusing on assessing the environmental impacts of other forest services.

The results are based on a detailed LCA approach applied to the forest management context using Simapro. All LCA tools (SimaPro, GABI, Umberto, OpenLCA) were developed for general purposes across multiple sectors, including agriculture. SimaPro and GABI have been used to investigate LCA in biomass, wood production, and industries (Goglio et al., 2018; Lopes Silva et al., 2019). However, none of these tools were specifically designed to assess and readily consider the environmental effects of selected forest management practices in the earlier stages of forestry, such as seedling and timber cutting. Hence, the methodology and findings presented in this paper can serve as a foundational framework for future research of LCA in forestry aiming at evaluating the environmental impacts of various forest ecosystem services such as non-wood production, recreation, and hunting.

An average/typical year was chosen for the assessment. Specifically, we chose the year 2016, which was a balanced year in terms of supply and demand, including a balanced level of timber harvest. Compared to other LCA studies in forest management, there are more options for setting a time range, e.g., a “whole rotation approach” and a “single moment approach” (Price, 1987; Klein et al., 2015), however, it is practically unfeasible to include the entire production or rotation period, given the length of time (e.g., 100 years).

Another important methodological starting point was the establishment of system boundaries for the LCA. First of all, we consider it crucial to point out that this is not the production phase of the life cycle, as reported in some LCA studies (Ferro et al., 2018), but the first phase, i.e., the biotic harvesting phase. This study’s boundary system was set from the seed collection to timber extraction so that the forest management operations were assessed across the entirety of the first life cycle phase. It is clear from the published LCA results that the choice of system boundaries has a significant effect on the LCA results (Peñaloza et al., 2019).

In the context of forestry in the Czech Republic, seedling activities exhibited similarities. In contrast, three scenarios of the harvesting methods that are practiced in the country were selected for the LCA study (Figure 2). The first scenario depicted complete tree felling and processing carried out with a chainsaw, alongside timber extraction utilizing a horse. This practice took place in forested areas surrounded by waterlogged terrain or muddy soil, making it difficult for a tractor or other vehicle to access. In the second scenario, the process of tree felling and processing was accomplished through a combination of chainsaw work (constituting 90% of the total hours worked) and harvester operation (accounting for the remaining 10% of hours). The extraction phase involved the use of a tractor. In the third scenario, a different approach was taken, with chainsaw usage reduced to 23% of the hours worked, while the majority of time (77% of hours worked) was dedicated to utilizing the harvester. For extraction, a tractor equipped with a winch was employed. In the third scenario, a small truck played a crucial role by providing essential spare parts, materials, and fuel to support the efficient operation of the forestry machinery.

The results of the LCA on silvicultural and harvesting operations show a significant contribution from the maintenance of the forest road network to the environmental impacts of this phase. Depending on the different harvesting scenarios, the share of the impacts from the maintenance of road network ranges from 53.3 to 76.2%. Similarly, Đuka et al. (2017) reported a share of 60% from this activity. In other articles, this ratio is quite variable. For example, Heinimann and Maeda-Inaba (2003) stated that in Switzerland, three factors are decisive for environmental impact: slope, transport distance for base course materials, and roadbed width. However, based on the described models, the impact can be very different. Dodson (2021) points to the effects of climate change on increasing forest road maintenance costs, as water quality could deteriorate. In addition, it draws attention to the higher maintenance costs due to the frequent bridges on forest roads and thus the higher environmental impact. On the other hand, forest road maintenance may be less energy intensive, as Whittaker et al. (2011), due to the smaller quantities of aggregate used per km, and fewer machinery operations.

Forest roads are an essential technical infrastructure within forest ecosystems (Drosos et al., 2013), serving a whole array of harvesting and silvicultural operations. In addition to these activities, forest roads serve other purposes such as hunting, hiking, fishing, forest fruit picking, and others that were not included in the LCA calculation. Their share of the environmental impact on the road network will be the subject of further research.

The high environmental burden is primarily due to the high proportion of gravel and bitumen for the maintenance of the L1 category roads. An option to eliminate this aspect is to move the roads from the L1 category and subsequent categories to the lower ones, i.e., to create a high-quality backbone network, followed by the lower categories where appropriate. It is also possible to use different technology, e.g., compacted aggregate can be used instead of bitumen, as gravel performs significantly better in terms of global warming and overall energy consumption. Another option is to use a variant with the lowest environmental impact when designing forest roads (Hayati et al., 2013; Picchio et al., 2018). It is also a question of making the forest accessible through an optimal forest road network, both from a technological and environmental perspective (Drosos et al., 2013), as well as, for example, fire protection (Majlingová, 2012).

Other significant impactors are associated with felling, and in particular, with timber extraction. These impacts vary considerably according to the machinery used (Đuka et al., 2017). These activities are mirrored in all impact categories, especially in cumulative energy demand and global warming. From this analysis, it can be seen, that the aforementioned level of impact categories is primarily influenced by two production operations, i.e., felling and extraction. Also, seedling production in forest nurseries, including seed collection and the tending of young stands, is not negligible. Nurseries have a higher effect than the tending of young stands in both categories. Global warming is 20% higher for nursery seedling production, and the cumulative energy demand is 39% higher. In silviculture, plantation protection is strongly reflected in almost all impact categories within this production operation. The electricity used for irrigation and fossil fuels used for growing seedling and transportation were the major sources of emission. In contrast, Aldentun (2002) stated that the major sources of emissions were the fossil fuels used for heating the greenhouses and for seedling transportation. The difference is due to the different cultivation technology.

The choice of harvesting technology is a challenging problem where several inputs are taken into account. In particular, site conditions (terrain configuration, slope, forest weeds), harvested assortments (their stem volume and length), extraction distance, and the volume of transported timber. A comparison of the three scenarios shows that the leading environmental impacts are associated with the use of the harvester. These results fly in the face of the economic intensity, where, contrarily, the best results are achieved when a harvester is employed. Additionally, although we did not analyze the biodiversity implication of the three-harvesting technology, horse-powered prevented soil compaction (García-Tomillo et al., 2017), compared to heavy machinery. Soil compaction can degrade environmental quality (bulk density and porosity) of various soil microorganisms and biota, thereby limiting their growth (Kretzschmar, 1991; Tan et al., 2008; Frey et al., 2009; Ugawa et al., 2020). The economic effect and the working safety are currently the criteria for evaluating economic activity, and this fact explains the rapidly increasing share of harvesting technologies used in forestry sector (Dvořák et al., 2019). However, the emphasis on the economic effect of production operations is in contrast to the impact on energy consumption and the global warming criterion. This was also confirmed by Kühmaier et al. (2022). The solution is to seek the optimum eco-economic efficiency in forest management. The innovation of newly designed mechanisms can be a promising solution.

Our research aimed to propose a methodological procedure for the LCA in the forestry sector. The work on the LCA was particularly challenging because the silviculture and harvesting of raw timber involve 20 production operations. The analysis was carried out in as much detail as possible while complying with all legislative, technical, technological, and material standards. The model was developed for a spatial unit defined by the forest typology in the Czech Republic (a group of forest habitat types) and for the most common tree species, i.e., spruce. Processed methodology can be applied to other tree species and forest habitat type groups, possibly to higher territorial units, forest estates, and also to the entire forestry sector at the national level.

The LCA was based on long-term knowledge of forest typology, forest management planning, forest economics, experience with forest technologies, and regulatory measures. In terms of the use of detailed data on forest management and knowledge of the forest ecosystem, this is an original approach based on many years of analysis and knowledge, which are used in practice by the government and forest owners. Three scenarios were selected, differing in the method of harvesting. The highest impact was recorded for the third scenario, i.e., chainsaw felling (23% of hours worked) and harvester operation (77% of hours worked) and extraction by a tractor (Supplementary Table S8).

The strength of our study was that we used primary data, unlike many other studies that use secondary data. The primary data are based on detailed conditions given by a specific forest ecosystem characterized by Group of Forest Habitat Types. Furthermore, these are the basic approaches used in life cycle assessment, which are often simplified in the case of the forestry sector at the expense of meaningful results. The results can be used in other regions or throughout the Czech Republic.

The boundaries of the silviculture and harvesting system can be extended to other stages of timber utilization in additional research. Further analysis of other forest ecosystem services, i.e., not only timber production but also non-timber and non-market ecosystem services, can be pursued.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding authors.

MH: Conceptualization, Investigation, Resources, Supervision, Writing – original draft, Writing – review & editing. KP: Conceptualization, Investigation, Methodology, Resources, Visualization, Writing – original draft, Writing – review & editing. RP: Resources, Visualization, Writing – original draft, Writing – review & editing. MT: Conceptualization, Formal analysis, Investigation, Methodology, Resources, Visualization, Writing – original draft, Writing – review & editing. MP: Data curation, Resources, Writing – review & editing.