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Timber harvesting operations using heavy forest machinery frequently results in severe soil compaction and displacement, threatening sustainable forest management. An accurate prediction of trafficability, considering actual operating conditions, minimizes these impacts and can be facilitated by various predictive tools. Within this study, we validated the accuracy of four terramechanical parameters, including Cone Index (MPa, Penetrologger), penetration depth (cm, Penetrologger), cone penetration (cm blow−1, dual-mass dynamic cone penetrometer) and shear strength (kPa, vane meter), and additionally two cartographic indices (topographic wetness index and depth-to-water). Measurements applying the four terramechanical approaches were performed at 47 transects along newly assigned machine operating trails in two broadleaved dominated mixed stands. After the CTL thinning operation was completed, measurement results and cartographic indices were correlated against rut depth. Under the rather dry soil conditions (29 ± 9 vol%), total rut depth ranged between 2.2 and 11.6 cm, and was clearly predicted by rut depth after a single pass of the harvester, which was used for further validations. The results indicated the easy-to-measure penetration depth as the most accurate approach to predict rut depth, considering coefficients of correlation (rP = 0.44). Moreover, cone penetration (rP = 0.34) provided reliable results. Surprisingly, no response between rut depth and Cone Index was observed, although it is commonly used to assess trafficability. The relatively low moisture conditions probably inhibited a correlation between rutting and moisture content. Consistently, cartographic indices could not be used to predict rutting. Rut depth after the harvester pass was a reliable predictor for total rut depth after 2–5 passes (rP = 0.50). Rarely used parameters, such as cone penetration or shear strength, outcompeted the highly reputed Cone Index, emphasizing further investigations of applied tools.
Marian Schönauer; Stephan Hoffmann; Joachim Maack; Martin Jansen; Dirk Jaeger. Comparison of Selected Terramechanical Test Procedures and Cartographic Indices to Predict Rutting Caused by Machine Traffic during a Cut-to-Length Thinning-Operation. Forests 2021, 12, 113 .
AMA StyleMarian Schönauer, Stephan Hoffmann, Joachim Maack, Martin Jansen, Dirk Jaeger. Comparison of Selected Terramechanical Test Procedures and Cartographic Indices to Predict Rutting Caused by Machine Traffic during a Cut-to-Length Thinning-Operation. Forests. 2021; 12 (2):113.
Chicago/Turabian StyleMarian Schönauer; Stephan Hoffmann; Joachim Maack; Martin Jansen; Dirk Jaeger. 2021. "Comparison of Selected Terramechanical Test Procedures and Cartographic Indices to Predict Rutting Caused by Machine Traffic during a Cut-to-Length Thinning-Operation." Forests 12, no. 2: 113.
In Germany, management restrictions for Norway spruce ( (L.) H. Karst.) due to climate change lead to increasing interest in Douglas fir ( (Mirb.) Franco) as a potential substituting species. However, Douglas fir requires cost-intensive silvicultural treatments, such as periodic thinnings and, in particular, pruning. In order to improve the efficiency of such treatments, a new tending system with an adapted two-step work system was analyzed. The new system, using electric pruning shears and the backpack clearing saw Husqvarna 535FBX âSpacerâ, was compared to the conventional three-step work system, using handsaw and chainsaw and characterized by tree selection previously conducted as an independent work step. Time and motion studies to determine productivity and costs, as well as ergonomic analysis through heart rate measurements and posture analysis were conducted. Overall, the new system was found to be more productive and to have lower costs, with 8.9 trees per scheduled system hour (4.17 ⬠tree), compared to the conventional system with 8.1 trees per scheduled system hour (4.44 ⬠tree). Ergonomic improvements with the new system could be mainly observed during the felling of competing trees, when the level of heart rate reserve was reduced by 9.3 percent points, compared to the conventional system. However, significant advantages in reducing unfavorable body postures expected for the âSpacerâ could not be confirmed. Since time savings within the new system were mainly attributed to the adaptation of workflow and the use of the electric shears during pruning, it should be considered to replace the âSpacerâ within the new system by light chainsaws for best results under the conditions investigated.Picea abies Pseudotsuga menziesii â1 â1
Marian Schönauer; Stephan Hoffmann; Martin Nolte; Dirk Jaeger. Evaluation of a new pruning and tending system for young stands of Douglas fir. Silva Fennica 2021, 55, 1 .
AMA StyleMarian Schönauer, Stephan Hoffmann, Martin Nolte, Dirk Jaeger. Evaluation of a new pruning and tending system for young stands of Douglas fir. Silva Fennica. 2021; 55 (2):1.
Chicago/Turabian StyleMarian Schönauer; Stephan Hoffmann; Martin Nolte; Dirk Jaeger. 2021. "Evaluation of a new pruning and tending system for young stands of Douglas fir." Silva Fennica 55, no. 2: 1.
Recently, forest operations are facing unfavorable climatic conditions more frequently. In Central Europe, machine trafficability and induced soil disturbances are negatively affected by periods of high precipitation and less intensive frost during ground-based harvesting operations. Winch-assist technology is assumed to reduce soil disturbance by forest machines in steep terrain. Still, the potential positive effects of winches to assist traction of forest machines in flat terrain have rarely been surveyed. In this study, a field trial was conducted in flat terrain (slope < 5%). There, a forwarder with an integrated traction-assist was monitored during six consecutive machine passes on a permanent machine operating trail. The first section of the machine operating trail was passed without traction-assist, the remaining section with traction-assist, resulting in two treatment groups. To assess soil impacts, three test plots were positioned per treatment group. Within these plots, pre- and post-operational soil bulk density, soil displacement and rutting were determined. Additionally, wheel slippage and cable tensile force were examined, using incremental rotary encoders and a flexible tensile force measurement kit, respectively. It was observed, that wheel slippage responded inversely with tensile force. Traction-assist technology reduced wheel slippage from 5.3 ± 11.9% to 0.37 ± 10.19% along the section of the machine operating trail, as compared to results from the unassisted section. Although wheel slippage was significantly reduced, no mitigating effect by the usage of traction-assist technology on soil disturbance could be observed, probably due to the low volumetric water content of 27%.
Marian Schönauer; Thomas Holzfeind; Stephan Hoffmann; Franz Holzleitner; Bastian Hinte; Dirk Jaeger. Effect of a traction-assist winch on wheel slippage and machine induced soil disturbance in flat terrain. International Journal of Forest Engineering 2020, 1 -11.
AMA StyleMarian Schönauer, Thomas Holzfeind, Stephan Hoffmann, Franz Holzleitner, Bastian Hinte, Dirk Jaeger. Effect of a traction-assist winch on wheel slippage and machine induced soil disturbance in flat terrain. International Journal of Forest Engineering. 2020; ():1-11.
Chicago/Turabian StyleMarian Schönauer; Thomas Holzfeind; Stephan Hoffmann; Franz Holzleitner; Bastian Hinte; Dirk Jaeger. 2020. "Effect of a traction-assist winch on wheel slippage and machine induced soil disturbance in flat terrain." International Journal of Forest Engineering , no. : 1-11.