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Report2014

Report on methodology for reducing ground damages during forestry operations

Nordfjell, Tomas; Lindroos, Ola

Abstract

During forestry operations large volumes of timber are extracted from forest to road-side by heavy vehicles. During those operations, the annual distance driven off-road in Sweden is estimated to be at least 3 million km at a yearly harvest of 90 million m3 of wood. If using those numbers and estimating the total driven distance for the whole of Europe the corresponding distance will be something like 23 million km off-road driving with heavy forest machines. The aim of this study was to analyze the results from T2.7 and T8.3 (deliverables D2.11 and D8.3) regarding the applicability for sensor technique (Thermal camera, Short Wave Infra-Red camera and Multispectral camera) for estimation of soil moisture content, and by this the soil bearing capacity. The analysis was based on a literature review in relation to the presented results in D2.11 and D8.3. There are three ground related factors that mainly influence the soil bearing capacity for heavy forest machines; namely soil type, soil moisture content, and reinforcement of the ground. All types of forest soils are reinforced in a higher or lower degree. This reinforcement consists of e.g. rocks, boulders, stumps and root systems, ground vegetation mat (shrub and sprigs), as well as eventual logging residues. The ground vegetation can be used to estimate the most common soil moisture conditions at a specific forest site. The tests done with the different sensors in D2.11 and D8.3 are too limited for validation of how well the technique can estimate low ground bearing capacity. However, the different sensors seem to give interesting opportunities for further development of technique for such estimations. The short wave infra-red camera gives a good possibility to estimate the soil surface moisture content, after calibration. However, its capacity to make measurements below the soil surface is unclear, and probably non-existing. The test rig was also equipped with a multispectral camera that in this case was used to differentiate soil without vegetation from the vegetation and from other subjects. However, if a multispectral camera could also be used to differentiate between different types of vegetation, more information about the soil bearing capacity could be gained. It is most likely that a sensor technique based on the principles presented in D2.11 and D8.3 can add valuable information and together with new depth to water maps be used for online estimations of forest soil bearing capacity. It is however of vital importance that validation studies is done where comprehensive soil mechanical measurements are done on spots measured by such sensor technique.

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Publisher: Intelligent sensing and manipulation for sustainable production and harvesting of high value crops, clever robots for crops (CROPS), FP7 EU, grant agreement no 246252.