Development of a methodology for tracking the volume of forest resources from felling to the enterprise using an unmanned aerial vehicle

. The volume of forest resources is the most important characteristic in tracking the supply chains of raw materials, along with species and quality. To date, there is no unified automated methodology designed to track the movement of forest resources. The paper considers the use of an unmanned aerial vehicle for the purposes of accounting and accurate calculation of timber volumes both in the standing and in the form of stacks of round timber. The users of the presented methodology are timber industry enterprises, as well as authorities and departments for the purpose of state control. The developed methodology will make it possible to obtain prompt and accurate information on the volume of timber along the entire path of their extraction and processing. This, in turn, will reduce the cost of the procedure for assessing the volume of timber, make the procedure for monitoring their movement more independent and transparent.


Introduction
The importance of effective accounting systems for forest resources cannot be overstated, given the vital ecological, economic, and social functions that these resources serve.This paper assesses the significance of accurate accountancy for forest resources by providing pertinent statistics and referring to real literary sources in the field of ecology and natural resource management.
According to the Food and Agriculture Organization (FAO) of the United Nations, forests cover approximately 4 billion hectares (9.88 billion acres) of Earth's land surface, representing about 30% of the total land area [1].They are essential for maintaining biodiversity and the health of ecosystems, sequestering carbon, and providing food, medicine, and livelihoods to millions of people [2].
As noted by the United States Forest Service, around 20% of global forested areas are currently impacted by excessive exploitation and development activities [3].Recognizing the importance of forest resources and the need to manage them effectively is essential.
Proper accounting and management of forest resources can serve multiple purposes.Accounting can ensure responsible resource extraction and development while preserving the natural balance in the ecosystems [4].It can also provide a solid foundation for policy-making and informed decision-making, increasing public awareness about the value of forests, and promoting sustainable development through various strategies.
Furthermore, reliable data supported by appropriate accounting methodologies can facilitate the monitoring of the state of forests and help identify trends in deforestation, degradation, and unsustainable forestry practices [5].This can enable governments, policymakers, and conservation organizations to make data-driven decisions and design effective strategies for forest management and preservation.
Finally, the inclusion of forest resources accounting in national and international economic systems can ensure fair and accurate reporting of the environmental impact of development activities and promote a more ecologically responsible business approach [6].
The importance of accounting for forest resources is unequivocal, as it facilitates informed decision-making, sustainable management, and the maintenance of ecological balance.Comprehensive and accurate forest accounting systems are vital for ensuring the long-term health and preservation of these precious and indispensable ecosystems.
UAVs are a reliable tool for collecting, analysing and accessing information about forest resources [7].They allow organizations and authorities to more accurately determine the state of forest ecosystems, the spatial distribution of various types of vegetation and monitor changes in forest areas.They can also be used to detect and prevent illegal activities in the forest, support sustainable forestry and make decisions based on objective data [8].

Methodology
Fig. 1 presents a preliminary portion of an image captured by a UAV, depicting a forest region with a spatial resolution of 5 centimetres per pixel.Watershed segmentation was then employed on the image, representing the raster as a three-dimensional surface with spatial coordinates and brightness level serving as height.However, the watershed segmentation algorithm often results in over-segmentation due to noise and local extremities, leading to numerous demarcated areas.
To control segmentation, a marker-based approach was utilized.Markers, which are connected components within an image, were designated using previously identified local brightness maxima.The outcome of this methodology is an automatically generated set of tree crown contours (Fig. 2).Afterward, crown contours were vectorized to enable integration and further processing within a geographic information system.By calculating the average pixel brightness of the digital image for different species, classification of the contours was achieved (Fig. 3).Crown diameter can be determined using the crown area.Assuming the crown has a circular shape, its diameter can be computed with the following formula: To convert the crown diameter to the trunk diameter at a height of 1.3 meters (d1.3), the suggested formula is: where d1.3 is the diameter of the tree trunk at the height of 1.3 m, cm; Dcr -tree crown diameter, m.
Using earlier acquired diameter measurements at 1.3 m height, tree trunk volumes can be calculated utilizing the Densin formula: where V is the volume of the tree, m 3 .The formula yields acceptable outcomes for tree trunks around 25 meters in height.For other instances, volumes should be increased by 3% for each meter exceeding 25 meters or decreased by 3% for each meter below.Subsequently, the stock is determined using the formula: where M -wood stock, m 3 /ha; n -the number of trees in steps of thickness, pcs.Further, when placing forest resources on the territory of a timber industry enterprise, the following sequence of steps is proposed: 1) Digital photography is being carried out from the UAV.Among the requirements for UAVs, it is necessary to highlight the presence of an onboard satellite navigation system, as well as the presence of a digital camera.
Digital photography from the UAV can be performed using different cameras at different heights, depending on the required measurement detail.For example, a digital camera with a matrix size of 12 megapixels at a height of 30 meters above the ground level will make it possible to form a digital terrain model (height model) with a detail of up to 1 cm/pixel.
2) Using specialized software (for example, Agisoft Metashape) performs automated photogrammetric processing of UAV digital photography data.The result of photogrammetric processing is a digital surface model (altitude values relative to sea level) -DSMs.l.. and an orthoimage of the territory (Fig. 4, 5).3) Using specialized geoinformation software (for example, QGIS , ArcGIS ) on the rendered image of the DSMs.l. points are fixed at the level of the earth's surface (site, road, open ground, etc.) on which there are no objects (Fig. 6).

6)
With the use of geoinformation software on the DSMg.l. the contours of round timber stacks are fixed and their storage volume is automatically calculated by summing the products of the areas of individual pixels multiplied by their height within the contour: where Vf -is the storage volume of a stack of round timber, Sp -is the area of an individual pixel (spatial resolution multiplied by 2), hp -is the height assigned to an individual pixel within the DTM at the sea level., n -is the number of pixels within the outline.7) The dense volume is calculated by multiplying the storage volume by the full-wood factor in accordance with GOST 32594-2013.

Result
A site located in Shenkursk (Arkhangelsk region, Russia) was chosen as the object of study.The experimental area was 0.83 hectares.The result of determining the timber stock according to the previously described method.
After accounting for the height equation, the timber volume at the experimental area equaled 82.7 cubic meters per hectare.Multiple ground test areas were used to verify the outcomes.The maximum discrepancy in determining the timber volume was 15%, an acceptable margin of error when evaluating forest resources following forestry industry standards.
When estimating timber volumes in the form of stacks, the result of the described technique is a detailed plan for arranging roundwood stacks (Fig. 7) with an indication of their volumes in a warehouse or terminal of a timber enterprise.

Discussion
The development of a methodology for tracking the volume of forest resources from felling to enterprise utilization using unmanned aerial vehicles (UAVs) has garnered significant interest in recent years.This discussion explores the various aspects of such a system, while considering the potential advantages, challenges, and future prospects associated with its implementation.
Firstly, the advantages of employing UAVs in forestry operations are numerous.They provide an efficient and accurate means of data collection, reducing the costs and time involved in manual and ground-based approaches.By capturing high-resolution images and collecting multispectral data, UAVs facilitate informed decision-making to ensure sustainable forest management.Additionally, real-time monitoring allows for the prompt detection of unauthorized logging activities and accurate tracking of timber extraction volumes, ultimately promoting accountability and transparency within the industry.
However, there are challenges associated with the integration of UAV technology into forestry operations.To begin with, the regulatory framework surrounding UAV usage varies across jurisdictions and must be taken into consideration during implementation.Ensuring compliance with local airspace regulations, flight restrictions, and data privacy concerns is essential.Moreover, processing and analysing the vast amounts of data collected by the UAVs require advanced information technology infrastructure and expertise, which might pose challenges for forestry organizations with limited resources.
In spite of these challenges, the potential benefits of adopting UAV technology in forest resource tracking cannot be overstated.As technological advancements continue to emerge, the cost-effectiveness and efficiency of UAVs are likely to improve further, making them an increasingly viable solution for diverse forestry applications.
The growing need to develop a UAV-based methodology for tracking forest resources also opens up new avenues for interdisciplinary research and collaboration.For instance, combining remote sensing techniques with advanced machine learning algorithms can help in automating data analysis and pattern recognition tasks.Additionally, integrating the UAVbased forest resource tracking system with GIS (Geographic Information System) platforms can facilitate spatial data management and visualization, enabling stakeholders to make better-informed decisions.
The development of a UAV-based methodology for tracking forest resources from felling to enterprise utilization presents a promising opportunity to improve sustainable forest management practices.By overcoming the associated challenges and harnessing the advantages offered by UAVs, this innovative approach has the potential to significantly impact the future of the forestry sector.

Conclusion
The developed methodology is in demand by a wide range of users.
First of all, these are timber enterprises that carry out an inventory of warehouses: directly near the plot (lower warehouses), in logistics hubs (upper warehouses), directly on the territory of the enterprise (terminals) Second, the authorities for the purpose of state control.In Russia, the Federal Forestry Agency (Rosleskhoz) is entrusted with the functions of supervision in the field of acceptance, transportation, processing and storage of wood, wood accounting and transactions with it.Mandatory requirements in the field of timber turnover in relation to controlled persons include, among other things, the accounting and technical direction, that is, determining the characteristics of wood, accounting for changes in characteristics in order to form information about wood when organizing processes.
The accounted timber is reflected by the participants in the turnover of timber, in addition to the Unified State Automated Information System of timber accounting, even in accounting and tax accounting.Accuracy, reliability of accounting forms not only the idea of the timber owner and the state about the physical flows of timber, but also about the economic aspects of the activity, with all the associated risks.Credit organizations are also interested in the results of the study.In particular, banks in the course of collateral transactions can reliably assess the financial condition of the organization that requested credit.
Thus, the developed methodology will help both forest users and regulatory agencies to receive prompt and accurate information about the volume of timber in the territory of their storage.This, in turn, will reduce the cost of the procedure for assessing the volume of timber, make the control procedure more independent and transparent.

Acknowledgment
The research was supported by the Russian Science Foundation and the Government of the Arkhangelsk Region, project no.22-11-20025.

Fig. 1 .
Fig. 1.An example of a UAV digital imaging.

Fig. 6 .
Fig. 6.Points at ground level.4) Then the procedure for interpolating the height values at the points noted in the previous paragraph is performed.The result of this stage is a digital elevation model (DEM), that is, a model of the earth's surface without taking into account the objects placed on it.5) With the use of specialized geoinformation software (for example, QGIS, ArcGIS) from the pixel values of the DSMs.l.. the values of the DEM pixels are subtracted, as a result of which we obtain a digital surface model (height values relative to the ground level) -DSMg.l.: DSM s.l.-DEM = DSM g.l.,