Skidding System Research Articles

Methodology for Assessing and Managing the Environmental Performance of Skidding and Feller Buncher Tractors

Systematic assessments on the effects of skidding systems on features of forest blueberry pine soil were conducted as part of this study. Assessing the ecological efficiency of forest skidding machines showed that the most significant impact (by 2.0–2.2 times) on soil compaction was observed at loading sites rather than during transportation. Lightweight loam density and sand density increased by 25% and 2%, respectively, after more than two passages of the skidding system. Pressure in 33L-32 tires of forestry machinery in operation on a solid surface varied from 46.5 kPa to 196 kPa at maximum load. Studying the impact of tires on soil compaction showed that the environmental efficiency of forestry equipment can be enhanced if the optimal tire pressure at average loads does not exceed 70 kPa for tracked vehicles and 150 kPa for wheeled vehicles in summer seasons. When ground grips were fully immersed, the pressure of forwarders on soil was reduced. These study results can be used to establish organizational and technological measures in order to manage the negative impact of skidding systems and to increase the environmental effects of their performance.

Моделирование взаимодействия лесных машин с почвогрунтом при работе на склонах

The urgency of the task of effective development of cutting areas on the slopes of mountains, hills, and hilly-ridge reliefs is primarily due to the depletion of available, special, lowland operational forests in Siberia and the Far East, which were once, not quite correctly, called forest-surplus regions of the Russian Federation. The operational woodlands that are convenient for development in Siberia and the Far East are largely depleted. To develop new ones, large-scale road construction is necessary, which requires significant financial expenses and reduces the already low profitability of logging production. It is also declining due to the ever-increasing volume of export of harvested timber, even if the cost of construction and maintenance of a new network of logging roads is not considered. Forest ecosystems located on slopes are among the most vulnerable. When working on the slopes with traditional systems of logging machines, it becomes necessary to cut a serpentine of skid trails, which later become concentrators of water and wind erosion. Currently, leading manufacturers of machinery and equipment for the forest industry, such as Ponsse, John Deer, Komatsu, and others, have developed technical solutions that significantly facilitate the operation of forest machine systems. Such solutions, first of all, include winches integrated into the transmissions of machines. Another solution is to use separate self-propelled winches remotely controlled by the operator of a forest machine, for example, T-winch. In this case, the machine does not receive additional weight from the winch integrated into it; however, the negative impact of forest machines on soils does not disappear, but has its own significant specifics. The article shows that when performing logging operations on slopes, primarily steep ones with slope angles exceeding 20–25°, it is necessary to make adjustments to the assessment of the destruction nature of the soil array and the patterns of the track depth formation under the influence of the skidding system. For citation: Rudov S.E., Shapiro V.Ya., Grigorev I.V., Kunitskaya O.A., Grigoreva O.I. Modeling the Interaction of Forest Machines with Soil when Working on Slopes. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 6, pp. 121–134. DOI: 10.37482/0536-1036-2021-6-121-134

Modernization of the cable skidding system by upgrading the articulated carriage

The article presents the constraining factors (including climatic) of the use of traditional solutions for skidding round wood (logs) in the winter cutting period of 2019-2020 years in the Northwestern Federal District of the Russian Federation on non-straight forwarding roads, a technical solution is proposed to improve the existing cable skidding systems (CSS) using a new carriage structures - articulated carriage (AC), as well as the improvement of this design by strengthening the structure with stiffeners to increase reliability based on the analysis of the stress-strain state of the AC parts by mathematical modeling in the SolidWorks Simulation environment. The implementation of the model of the proposed solution for the modernization of the AC by printing on the DF-Print 3D printer in the future is given. The use of the new modernized design of the AC contributes to solving the problem of the skidding of round wood in the winter cutting period.

Modeling the effect of wheeled tractors and skidded timber bunches on forest soil compaction

An increasing demand for forest products incites a large number of log transportation operations, which may lead to negative consequences for the soil and the ecosystem as a whole. This paper is focused on establishing a mathematical model to estimate the soil deformation and compaction processes under tires of wheeled forest machines and individual components of the skidding system such as forwarder, limbs, butts, and tops of tree-lengths in high latitudes, permafrost soil and forests. The method applied is based on simulating the impact processes of elastic tires and the skidding system on the soil through a mathematical device for the measurement of the compaction parameters for different types of soil and the size of the shelterbelt. The effectiveness of the proposed models was evaluated according to experimental results. The influence of the rheological (elastic, viscous, and plastic) properties of soil were studied. The elasticity of tires and the running speed of forest machines can help to control the performance of forest machines. This can be done by reducing the pressure exerted on the soil and increasing the number of skidder passes 1.5-2-fold. Comparative analysis showed that the calculated data differ from the experimental ones by no more than 10%. The obtained results and the developed model will allow for a qualitative and quantitative assessment of technological impact on the soil during the projecting maps for logging operations.

Modeling the effect of skidded timber bunches on forest soil compaction

An increasing demand for forest products incites a large number of log transportation operations, which may lead to negative consequences for the soil and the ecosystem as a whole. This paper presents a mathematical model to estimate the soil deformation and compaction processes under the influence of individual components of the skidding system, such as the forwarder, limbs, butts, and tops of tree-lengths in high latitudes, permafrost soil, and forests of the cryolithic zone. The effectiveness of the proposed model was evaluated according to experimental results. Comparative analysis showed that the calculated data differ from the experimental data by no more than 10%. The deformation of the soil by the bunch of tree-length logs occurs due to shearing processes. It has been established that the initial vertical stress exceeds the radial stress by 30–40%. The result of estimating the dependency of the shelterbelt width on the number of tree-length logs showed that the limit values for logs amount to 4–6 units for the mild, medium, and solid soil categories. The obtained results and the developed model will allow for a qualitative and quantitative assessment of the technological impact on the soil during the projecting of maps for logging operations.

Прогнозная модель воздействия трелевочной системы на лесной почвогрунт в сложных сезонно-климатических условиях

In the Russian Federation logging operations are traditionally carried out in winter. This is due to the predominance of areas with swamped and water-logged (class III and IV) soils in the forest fund, where work of forestry equipment is difficult, and sometimes impossible in the warm season. The work of logging companies in the forests of the cryolithozone, characterized by a sharply continental climate, with severe frosts in winter, is hampered by the fact that forest machines are not recommended to operate at temperatures below –40 °C due to the high probability of breaking of metal structures and hydraulic system. At the same time, in the warm season, most of the cutting areas on cryosolic soils become difficult to pass for heavy forest machines. It turns out that the convenient period for logging in the forests of the cryolithozone is quite small. This results in the need of work in the so-called off-season period, when the air temperature becomes positive, and the thawing processes of the soil top layer begin. The same applies to the logging companies not operating in the conditions of cryosolic soils, for instance, in the Leningrad, Novgorod, Pskov, Vologda regions, etc. The observed climate warming has led to a significant reduction in the sustained period of winter logging. Frequent temperature transitions around 0 °C in winter, autumn and spring necessitate to work during the off-season too, while cutting areas thaw. In bad seasonal and climatic conditions, which primarily include off-season periods in general and permafrost in particular, it is very difficult to take into account in mathematical models features of soil freezing and thawing and their effect on the destruction nature. The article shows that the development of long-term predictive models of indicators of cyclic interaction between the skidding system and forest soil in adverse climatic conditions of off-season logging operations in order to improve their reliability requires rapid adjustment of the calculated parameters based on the actual experimental data at a given step of the cycles.

ОПРЕДЕЛЕНИЕ МАССЫ ГРУЗОЗАХВАТНОГО СРЕЗАЮЩЕГО МЕХАНИЗМА ДЛЯ АЭРОСТАТНОЙ СИСТЕМЫ ТРЕЛЕВКИ

The article presents the results of practical and theoretical studies in the field of application of balloon-cable systems capable of operating in the mode of vertical removal of a tree from a forest canopy and its subsequent transportation to a loading point. The relevance of this technological direction lies in the impossibility of traditional forestry equipment to carry out the process of harvesting and transporting wood without violating environmental requirements. It is noted that clear environmental effect can be achieved using air wood harvesting and transportation means, in particular when using balloon systems. A brief description of the operation of the load-gripping cutting mechanism used for the vertical skidding system using balloon-cable systems is given. It is indicated that the main parameters of these mechanisms that affect their effective operation are the mass of the mechanism and the speed of its lowering to the tree crown. The method of calculating the optimal mass of load-gripping cutting mechanism is given depending on the type of wood being processed and the speed of lowering. Brief recommendations for calculating mass and speed of movement with the possible use of an ascending load-gripping cutting mechanism are given

Исследование процесса разрушения мерзлых и оттаивающих почвогрунтов при воздействии трелевочной системы

Wood logging in the forests of the cryolithozone is growing more urgent for the Russian Federation due to the depletion of available reserves of mature commercial forests in southern and Central Siberia, the Republic of Buryatia, and Khabarovsk Krai, while the development of woodworking enterprises in the Far Eastern Federal District. During the operation of modern forest machines, for instance wheeled forwarders, the issues of their efficiency, first of all, mobility and technological productivity in the specific production and geotechnical conditions are now becoming ever more relevant. These circumstances together with the necessity to minimize the anthropogenic load on the environment put forward the problem of optimizing the number of passes of the skidding system by one run into the most pressing ones. Special conditions for the operation of skidding systems take place in logging operations on frozen and thawing soils. In the first case, there is a sufficiently large volume of ice in the soil massif. The ice has a great impact on increasing the bearing capacity of the soil under the influence of the initial vertical load of the skidding system. In the second case, frozen soil is oversaturated with water when thawing; therefore, the natural bonds between the solid particles grow week, and the physical and mechanical properties of the soil lose their original values. The forwarder forms a rut in the immediate area of contact of the wheel with the soil. The larger the size of the area, the higher the force transferred to the soil for implementation of the necessary traction. We have developed the mathematical model of calculation of parameters of the destruction process of the thawing soil massif on the border with the permafrost zone. The model allows to make an assessment of hypothetical values of depth of the formed rut including engineering capabilities of forwarders and their maneuvering in the work environment at the design stage. For citation: Rudov S.E., Shapiro V.Ya., Grigorev I.V., Kunitskaya O.A., Grigoreva O.I. The Study of the Destruction Process of Frozen and Thawing Soils Exposed to the Skidding System. Lesnoy Zhurnal [Russian Forestry Journal], 2020, no. 2, pp. 101–117. DOI: 10.37482/0536-1036-2020-2-101-117

Особенности оценки расчетной рейсовой нагрузки на антецедентной стадии проектирования бесчокерной трелевочной системы на основе машинного эксперимента

Efficiency improving of the forest sector cannot be achieved without development of the forest machines design methods. Analysis of the studies devoted to this issue shows that insufficient attention was paid to it. The research objectives were to analyze the influence of the probabilistic nature of tree parameters on the load from moving tree bundle acting on a chokerless skidding system, and to determine the range of values of the necessary load-carrying capacity of the system’s chassis based on the analysis results. The research was based on computer experiment consist of tree bundle generating necessary for the full filling of the skidding system chain grapple. The parameters of generated trees were determined by the taxation conditions of the Karelian Republic forest stands. Forty five variation series characterizing the mass distribution of a skidding tree bundle were obtained based on the computer experiment results processing. The variation curve shifted to the right side along the mass axis of a tree bundle, and its shape changed with the increase of chain grapple size. The curve was stretched slightly and became more flat; the maximum value of the relative frequency of tree bundle mass decreased. Tree bundle mass fluctuated significantly at the same size of chain grapple. The difference between the maximum and minimum mass values of tree bundles was in the range of 3.7–5.6 tons. It increased with the increase of chain grapple size. The analytical dependence of tree bundle mass necessary for determina-tion the load-carrying capacity of the chokerless skidding system chassis on the chain grapple size was found. The recommended values of the chassis load-carrying capacity in the considered range of chain grapple sizes (1–2.2 m2) are in the range of 5.5–12.4 tons. The obtained results can be used at antecedent design stage of forest machines, as well as at technical and economic assessment of chokerless skidding systems operating in the Republic of Karelia.For citation: Shegelman I.R., Budnik P.V. Features of Calculated Truck Load Estimation at Antecedent Design Stage of Chokerless Skidding System Based on Computer Experiment. Lesnoy Zhurnal [Forestry Journal], 2019, no. 3, pp. 82–96. DOI: 10.17238/issn0536-1036.2019.3.82Funding: the research was carried out within the framework of the grant of the President of the Russian Federation no. MK-5321.2018.8.

Особенности контактного взаимодействия трелевочной системы с мерзлым почвогрунтом

Особенности контактного взаимодействия трелевочной системы с мерзлым почвогрунтом

Shape of skidder productivity function for ground based skidding system in Caspian forests

Understanding how stand and terrain parameters impact the productivity of harvesting machines is important for determining their optimum use Time and motion studies were conducted to evaluate the impact of terrain characteristics and work methods on skidder productivity in cut to length skidding system in easy and difficult terrain condition in Caspian forests It was found that the productivity for skidding operation on selective cutting sites classified as easy and difficult terrain conditions ranged from to m h The results proved that logarithmic model in both skidding distance R and Y ln x and volume per turn R and Y ln x entered in the model in easy condition Also the results proved that the logarithmic model in both skidding distance R and Y ln x and volume per turn R and Y ln x entered in the model in difficult condition These observations suggest that maximization of payload and optimization of timber extraction distance are more crucial for economic skidding on difficult sites Also skidding in easy terrain condition can increase productivity until m h It can be concluded that correct design of skidding trails can resulted in more production during ground based skidding in the region

Effect of the skid trail cross section and horizontal alignment on forest soil physical properties

Horizontal alignment and cross section characteristics of a skid trail in a ground-based skidding system including curves, wheel ruts and cross slope can impact on the forest soil. In this study the measurement of cross section and vertical alignment of skid trail in Bahramnia forestry plan was done using a levelling instrument. Horizontal alignment of skid trail including straight routes and curves was taken using polar methods. A 3D map of skid trail was produced in AutoCAD Civil3D software. Soil bulk density was measured after sampling the soil with a core sampler. Results showed that in straight routes, soil bulk density increased by increasing the cross slope of skid trail. Moreover, soil porosity decreased with the increasing cross slope. There was a significant difference between cross slopes in soil moisture. On curves, maximum bulk density occurred when the cross slope was 10%. Findings about soil porosity and moisture on curves of skid trails were similar to those of straight routes. Based on our findings, soil bulk density in wheel ruts was significantly lower than that in the middle part of skid trail. Soil bulk density in the silty soil texture of studied skid trails was a little more than ideal bulk density, so it cannot affect and restrict root growth.

Substantiation of Skidding System Trajectory when Changing Lanes Skidding

Отримано рівняння, що дає змогу будувати доцільну траєкторію руху початкової точки малогабаритної трелювальної системи під час її плавного переходу на нову смугу трелювання. Обґрунтування стосуються трелювання сортиментних лісоматеріалів у напівзавантаженому стані під наметом штучно створеного рядного лісового насадження. При цьому враховують таксаційні показники насадження, габарити трелювальної системи та схема розміщення дерев. Отримане рівняння доповнює відомі положення кінематики трелювальної системи і може використовуватися також для побудови перехідних кривих трелювальних волоків. Буде корисним для комп'ютерної імітації руху трелювальної системи під наметом штучно створеного рядного лісового насадження.

An optimization model to solve skidding problem in steep slope terrain

Abstract Designing an optimal off-road transportation network to allow access of logging systems to harvest sites is an important task in operational harvest planning. To address this issue, we have designed two variants of the capacitated network flow problem based on an integer programming (IP) approach with two sets of inter-dependent decisions. One set of decisions involves finding a feasible k -tree path network through segment linkages (routing flow) at a minimum variable cost, while another attends to the schedule of an even wood flow to the landing location(s) (transporting flow), within the scope of operational planning horizon. The mathematical models are then linked to a heuristic algorithm to identify the landing locations at the parcel level. The models were applied to a 680 ha area in the highlands of the Hyrcanian forests, in the north of Iran. The new formulation solved the problems using binary decision variables to represent transport of saw-logs from timber entry nodes to destination(s) by use of a ground-based machine skidder system. Then, the model uses continuous decision variables to represent transport of wood fuel to the same destination(s) by use of an animal skidding system. The results showed that the skidding costs and the length of the designed skid-trails were different based on the skidding systems and the types of products desired. Even though the models could generate an optimal solution, both of them could not address the real isolated timber node problem, where there is no accessible pathway for a skidding operation. As a promising point, the second model (splittable, animal systems) could partially solve the temporarily isolated timber nodes problem, where the timber nodes were not accessible by ground-based machine skidder systems.

Effect of log length on productivity and cost of Timberjack 450C skidder in the Hyrcanian forest in Iran

This paper presents research results on the performance of the Timberjack 450C skidder in timber skidding at two working sites of broadleaved trees in mountainous conditions in the Hyrcanian forest. To evaluate the current skidding system in the Hyrcanian forest in northern Iran and possibility of finding out better techniques and group organization an empirical time study has been conducted. The elements of the skidding work phase were identified and 123 cycles were recorded for short-log and long-log method. The models for effective time consumption, total productivity and unit cost of skidding in short-log and long-log method were calculated. The time consumption and productivity of skidding depend on several variables such as distances and slope, number of logs per cycle and volume. The average load per cycle in short-log and long-log method was 2.77 m<sup>3</sup> and 3.08 m<sup>3</sup>, the average one-way skidding distance was 380 and 497 m, the average slope was 18 and 20% in the short-log and long-log method, respectively. The average travel speeds of unloaded skidder were 5.74 km·h<sup>–1</sup> and the average speeds of loaded skidder were 7.67 and 6.16 km·h<sup>–1</sup> in short-log and long-log method, respectively. The average speeds of pulling the cable were 1.71 km·h<sup>–1</sup>, and of load winching 0.72 km·h<sup>–1</sup> and 0.69 km·h<sup>–1</sup>. The average outputs in short-log and long-log method were 10.86, 11.11 m<sup>3</sup>·effective h<sup>–1</sup>. Results indicated that hourly costs of operation were higher for the short-log method than for the long-log method (12.69 vs.12.40 USD·m<sup>–3</sup>).

Time consumption, productivity, and cost analysis of skidding in the Hyrcanian forest in Iran

The performance of the skidder Timber jack 450 C was presented in timber skidding of non-coniferous trees in hilly and mountainous conditions. An empirical time study was conducted to evaluate the current skidding system in Hyrcanian forest in northern Iran for improving production rate of skidding and finding out the production cost for planning. Based on the identified elements of skidding work phase and 130 recorded cycles, we calculated the models for effective time consumption, total productivity, and unit cost. The validity of the model was tested at 95% confidence interval. The average load volume per cycle was 2.82 m3, average one way skidding distance was 450 m, and the average slope was 18%. The average travel speed of unloaded skidder was 5.8 km·h−1, and the average speed of loaded skidder was 0.1 km·h−1 higher than the speed of the unloaded ones. The travel speed was predominantly affected by longitudinal slopes and types of strip roads. The average speed of pulling the cable was 1.16 km·h−1, and that of load winching was 0.74 km·h−1. The average outputs in skidding was 10.6 m3·h−1 and the unit cost was 12.1 US$ per hour. The time consumption and productivity of skidding depends on distances and slope, number of logs per cycle, volume, log length, etc. However, the influence of variables is not the same.

Evaluation of full tree skidding by HSM-904 skidder in patch cutting of aspen plantation in Northern Iran

This paper presents research results of the performance of HSM-904 grapple skidder using a full tree harvesting method in a non-native aspen Populus deltoides plantation in even terrain conditions in Shafaroud, Northern Iran. Patch cutting as a silvicultural method was used in the plantation (2,000 ha). To evaluate the newly introduced machine to a ground skidding system in the aspen plantation and the possibility to increase the production rate, an empirical time study was conducted. The elements of the skidding work phase were identified and 58 cycles were recorded for the study. The models for effective time consumption, total productivity and work phase models are calculated. The average load per cycle was 2.2 m<sup>3</sup>, the average one-way skidding distance was 253 m. The average travel speed of unloaded skidder was 5.53 km·h<sup>-1</sup> and the average speed of loaded skidder was lower than the speed of the unloaded one by 2.94 km·h<sup>-1</sup>. The average output in the study was 7.1 m<sup>3</sup> per effective hour and the unit cost was 13.9 USD·m<sup>-3</sup>.

Application of Artificial Neural Network in the Modeling of Skidding Time Prediction

Correct skidding time prediction and having precise information about the efficiency of skidding system rescues in a high quality of harvesting in a variable conditions of woodlands. This paper represents one of the Artificial intelligence methods, that is called Artificial Neural Network (ANN), for creating the predicting time model of wheeled skidder Timberjack 450C. The study of components of project has been done by continuous time study method. Effective factors on time of skidding were: skidding distance, skidding slope, winching distance, number of logs, and volume of load. In the present study, the time of 105 skidding cycles were investigated and used as the training data for neural network. The determination coefficient and the root mean square error for the best trained network were, 71% and 0.1778, respectively. The results showed that ANN provides a good accuracy for estimating the time of one cycle skidding time.

Influence of Chemical Properties on Soil Carbon Storage of a Tropical Peat Swamp Forest

Problem statement: It is important to investigate the seriousness of degradation of peat swamp forest caused by skidding system in terms of its function as a carbon sink. In this study, we formulated assumptions that conditions of our research site before the introduction of skidding system were in their natural states, thus that changes measured are clearly caused by skidding system. The objective of this study was to determine soil carbon storage of a tropical peat swamp forest in their natural state. Approach: Peat soil samples and bulk density were taken at 0-15 cm in a 0.3 ha plot at Sibu, Sarawak, Malaysia. The soil samples were analyzed for acidity, organic matter content, total carbon and total nitrogen. The humic acid extraction was also done and soil carbon storage values obtained by calculation. The calculation of carbon storage was by the bulk density method. Correlation analysis was used where applicable using Statistical Analysis System (SAS) version 9.1. Results: The results indicated that this tropical peat swamp forest rich in soil organic matter (97.645 %) but had extreme acidic environment (pH 3.737), thereby inhibiting organic matter decomposition rates. This tropical peat swamp forest also had large amounts of total carbon (48.823 %), low mineral nitrogen (0.896 %) and high C/N ratio (58.427). Stable carbon (soil carbon storage) positively correlated with unstable carbon (p<0.01, r = 0.43). The value of soil carbon storage was found to be 67.550 Mg Ha-1 (±61.49 % of unstable carbon). Furthermore, soil carbon storage positively correlated with soil organic matter (p<0.01, r = 0.43), total carbon (p<0.01, r = 0.43) and humic acid yield (p<0.01, r = 1.00). However, soil carbon storage negatively correlated with soil acidity (p<0.01, r = -0.55). Conclusion: From the results, it can be concluded that the tropical peat swamp forest indicates its specific natural state. This natural tropical peat swamp forest plays an important role as a sink rather than a source of carbon. The soil carbon storage in this natural tropical peat swamp forest was derived from unstable carbon and sensitive to soil acidity.

Effect of Skidding Operations on Soil Carbon Storage of a Tropical Peat Swamp Forest

Problem statement: There is still lack of a study that compares the soil carbon storage of kuda-kuda skidding system and excavator skidding system in tropical peat swamp forests. The objective of this study was to determine whether skidding operations affects soil carbon storage of a tropical peat swamp forest. Approach: Soil sampling was conducted on two different plots (0.3 ha each plot) to a depth of 15 cm under different skidding systems at Sibu, Sarawak, Malaysia. Plots were in the same forest concession area but considerably independent from each other. The soil samples were analyzed for acidity, organic matter content, total carbon, total nitrogen and total phosphorus. The humic acid extraction was also done and soil carbon storage values were obtained by calculation. The calculation of carbon storage was by the bulk density method. Unpaired t-test was used to compare variables under the two systems and correlation analysis was used to correlate variables (pH, soil organic matter, total carbon, total nitrogen, total phosphorus, C/N ratio, C/P ratio, humic acid yield, unstable carbon and stable carbon). Results: Soil organic matter, total carbon and unstable carbon were found to be negatively correlated with nitrogen but positively correlated with C/N ratio under kuda-kuda skidding system indicating that the lower nitrogen and higher C/N ratio markedly slowed decomposition process and enabled soil organic matter to accumulate as well as total carbon. Unstable carbon stocks under excavator skidding system was found to be higher (130.200 Mg ha-1) compared with kuda-kuda skidding system (117.124 Mg ha-1), under kuda-kuda skidding system, unstable carbon stock seemed to be preserved better and this was because of the better carbon storage. Although stable carbon contents of the two systems were similar, the excavator skidding system had faster decomposition processes, thus unstable carbon stocks decomposed more and this probably affects its function as carbon storage for further periods. Total phosphorus positively correlated with nitrogen but negatively correlated with C/N ratio under kuda-kuda skidding system, indicating that low nitrogen (0.914%) results in high C/N ratio (55.236) and this may have affected phosphorus (0.024%), thus enabled organic material to accumulate instead of losses through decomposition process. The low phosphorus (0.024%) or high C/P ratio (2346.345) under kuda-kuda skidding system resulted in decreased soil pH (3.552), thus enabled soil organic matter (97.603%) and total carbon (48.802%) to accumulate as well as unstable carbon stocks (117.124 Mg ha-1). Conclusion: The application of skidding systems in this peat swamp forest possibly alters their carbon storage particularly unstable carbon by altering their decomposition rates. Kuda-kuda skidding system is able to maintain decomposition process in this peat swamp forest. Hence, unstable carbon stocks can be preserved for further persistent breakdown processes, hence maintaining their function for carbon storage.