Die chronologische Liste zeigt aktuelle Veröffentlichungen aus dem Forschungsbetrieb der Hochschule Weihenstephan-Triesdorf. Zuständig ist das Zentrum für Forschung und Wissenstransfer (ZFW).
M.Sc. Caroline Bennemann,
Dr. rer. nat. Joachim Bernd Heppelmann,
Prof. Dr. Stefan Wittkopf,
Andrea Hauck,
Jochen Grünberger,
Bernd Heinrich,
Prof. Dr. Ute Seeling
Die Weiterentwicklung von Debarking Heads, die in mitteleuropäischen Wäldern einsetzbar sind, wurde seit 2014 bis zur Praxistauglichkeit durchgeführt. Durch den Umbau konventioneller Aggregate ist eine Einbindung der Entrindung in den Holzernteprozess möglich. Beim Einsatz entrindender Harvesteraggregate steigen die Holzerntekosten im Vergleich zur Nutzung von konventionellen Aggregaten verfahrensbedingt leicht an, diese Erhöhung wird jedoch von den vielfältigen Vorteilen aufgewogen. Der Verbleib der Rinde im Bestand sorgt für den Erhalt der rindengebundenen Nährstoffe im Wald. Bei Borkenkäferkalamitäten entzieht die Entrindung den Insekten den Brutraum. Bei der derzeitigen Waldschutzsituation entspannt die sofortige Entrindung der Fichte den Absatzdruck der Holzvermarktung. Der Wegfall der Rinde führt eine Gewichts- und Volumenreduktion der Rundholzsortimente mit sich. Das Holz trocknet schneller ab, beim Transport wird bei gleichem Holzvolumen weniger Gewicht transportiert, die Kraftstoffeinsparungen kommen der Umwelt und »dem Geldbeutel« zu Gute. Die Verbrennung entrindeter Sortimente führt zu weniger Ascheanfall im Brennraum und zu geringeren Feinstaubemissionen.
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Dr. rer. nat. Joachim Bernd Heppelmann,
Prof. Dr. Eric R. Labelle,
Prof. Dr. Stefan Wittkopf,
Prof. Dr. Ute Seeling
Berechtigungen: Open Access
Berechtigungen: Peer Reviewed
In-stand debarking with the use of modified harvesting heads: a potential solution for key challenges in European forestry (2019) European Journal of Forest Research 138 , S. 1067-1081.
DOI: 10.1007/s10342-019-01225-y
Modern forestry is increasingly confronted with challenges that appear with intensive forest management and the progression of the effects of climate change. The forestry sector is able to react to the changing conditions by adapting management plans, forest structure or planting tree species with a higher stress resistance. However, during stand management activities, silvicultural treatments and harvesting operations can have an impact on the further development of the remaining forest ecosystem. In Germany, the most widely used harvesting system for thinning operations is a single-grip harvester used for felling and processing trees followed by a forwarder for timber extraction from the machine operating trails to roadside. In this research project, debarking rollers and other modifications designed for Eucalyptus harvesting heads were tested on conventional harvesting heads for the first time to assess the possibility of adding debarking to mechanized forest operations under Central European conditions. Seven field tests with varying tree species, diameters and age classes, were established within German state forests in Lower Saxony and in Bavaria. These tests were repeated in both summer and winter seasons to evaluate the influence of associated tree sap flows on debarking quality. Three different harvesting heads were modified to assess the altered mechanical characteristics and setups. To assess debarking ability originating from head modifications, a photo-optical measurement system developed within the scope of the project was used. The results demonstrate that especially for summertime operations, simple modifications to currently used harvesting heads are able to provide an average debarking efficiency up to 90% depending on the modifications. Another key finding is that a negatively affected sap flow, experienced during wintertime operations, resulted in 46% lower debarking efficiency, while spruce bark beetle infestations only resulted in a wider spread of the variation. Additionally, the vertical position of the log within the tree proved to have an influence on debarking efficiency, resulting in 15% lower average debarking for butt logs and 9% for top logs as compared to middle logs. Since a debarking process requires the stem to be fed through the harvesting head on multiple occasions to remove bark, average harvesting productivity might be reduced by approx. 10% compared to productivity measured with conventional harvesting heads. Considering the results and the extent of the modifications, the system proved to be a potential addition to existing harvesting methods facing changing challenges in future forestry.
Dr. rer. nat. Joachim Bernd Heppelmann,
Prof. Dr. Eric R. Labelle,
Prof. Dr. Stefan Wittkopf
Berechtigungen: Open Access
Berechtigungen: Peer Reviewed
Static and Sliding Frictions of Roundwood Exposed to Different Levels of Processing and Their Impact on Transportation Logistics (2019) Forests 10 (7), S. 1-18.
DOI: 10.3390/f10070568
Load safety is a critical component of successful logistic operations. Different influencing factors can affect the necessity of intensive load securing methods. The most dominant factor is the friction characteristics of the intended cargo. A cargo with special requirements on load safety is debarked roundwood. Due to modern forestry challenges, larger amounts of debarked roundwood assortments are now being produced within German forest operations. To assess the influence of debarking onto the static and sliding frictions of Norway spruce, pulling tests were performed and compared to barked assortments. Results showed that a significant difference in both static and sliding frictions exists between barked and debarked assortments within the first seven days after harvesting. However, this significant difference became less prominent after the logs continued to dry out and no difference was detected after 21 days. Over the monitored period, debarked assortments presented a 40%–45% faster drying rate than barked assortments. This resulted in a calculated 11%–28% additional transportable net load (m3) of debarked roundwood assortments for long trailer systems. Hence, debarked roundwood can be treated similarly to barked roundwood if stored long enough prior to road transportation, while having the potential of increased savings within the wood logistic chain.
Dr. rer. nat. Joachim Bernd Heppelmann,
Prof. Dr. Eric R. Labelle,
Thomas Seifert,
Stefan Seifert,
Prof. Dr. Stefan Wittkopf
Berechtigungen: Open Access
Berechtigungen: Peer Reviewed
Development and Validation of a Photo-Based Measurement System to Calculate the Debarking Percentages of Processed Logs (2019) Remote Sensing 11 (9), S. 1-16.
DOI: 10.3390/rs11091133
Within a research project investigating the applicability and performance of modified harvesting heads used during the debarking of coniferous tree species, the actual debarking percentage of processed logs needed to be evaluated. Therefore, a computer-based photo-optical measurement system (Stemsurf) designed to assess the debarking percentage recorded in the field was developed, tested under laboratory conditions, and applied in live field operations. In total, 1720 processed logs of coniferous species from modified harvesting heads were recorded and analyzed within Stemsurf. With a single log image as the input, the overall debarking percentage was calculated by further estimating the un-displayed part of the log surface by defining polygons representing the differently debarked areas of the log surface. To assess the precision and bias of the developed measurement system, 480 images were captured under laboratory conditions on an artificial log with defined surface polygons. Within the laboratory test, the standard deviation of average debarking percentages remained within a 4% variation. A positive bias of 6.7% was caused by distortion and perspective effects. This resulted in an average underestimation of 1.1% for the summer debarking percentages gathered from field operations. The software generally performed as anticipated through field and lab testing and offered a suitable alternative of assessing stem debarking percentage, a task that should increase in importance as more operations are targeting debarked products.
Prof. Dr. Stefan Wittkopf
Beitrag zur Wuchsleistung und zur Klimaschutzfunktion von Mischwäldern (2018) Gut zu wissen, Bayerischer Rundfunk, Bayerisches Fernsehen .
Prof. Dr. Stefan Wittkopf
Debarking Heads am Harvester – Renaissance der Entrindung im Wald für den Waldschutz? (2018) Informationstagung der Forstwirtschaftlichen Zusammenschlüsse an der Bayerischen Waldbauernschule in Kelheim .
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Gerhard Radlmayr
Referent für Wissenstransfer und Forschungskommunikation
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