Tomi Kaakkurivaara, Nuutti Vuorimies, Pauli Kolisoja, Jori Uusitalo. (2015). Applicability of portable tools in assessing the bearing capacity of forest roads. Silva Fennica vol. 49 no. 2 article id 1239. https://doi.org/10.14214/sf.1239

Keywords: stiffness; light weight deflectometer; dynamic cone penetrometer; falling weight deflectometer; elastic modulus

Highlights: The dynamic cone penetrometer (DCP) and light falling weight deflectometer (LFWD) are useful tools for measuring bearing capacity; The measurement results are not same as with the falling weight deflectometer (FWD), but comparable.

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Forest roads provide access to logging sites and enable transportation of timber from forest to mills. Efficient forest management and forest industry are impossible without a proper forest road network. The bearing capacity of forest roads varies significantly by weather conditions and seasons since they are generally made of poor materials and the constructed layers may be mixed with subgrade. A bearing capacity assessment is valuable information when trafficability is uncertain and rutting is obvious. In this study, bearing capacity measurements were carried out using the light falling weight deflectometer (LFWD), the dynamic cone penetrometer (DCP) and the conventional falling weight deflectometer (FWD). The aim was to compare their measurement results in relation to road characteristics and moisture conditions. Data were collected from 35 test road sections in four consecutive springs and during one summer. The test road sections had measurement points both on the wheel path and the centre line. The data show logical correlations between measured quantities, and the study presents reliable regression models between measuring devices. The results indicate that light portable tools, the DCP and the LFWD, can in most cases be used instead of the expensive falling weight deflectometer on forest roads.

Kaakkurivaara, Natural Resources Institute Finland, Green technology, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: tomi.kaakkurivaara@gmail.com
Vuorimies, Tampere University of Technology, P.O.Box 600, FI-33101 Tampere, Finland E-mail: nuutti.vuorimies@tut.fi
Kolisoja, Tampere University of Technology, P.O.Box 600, FI-33101 Tampere, Finland E-mail: pauli.kolisoja@tut.fi
Uusitalo, Natural Resources Institute Finland, Green technology, Kaironiementie 15, FI-39700 Parkano, Finland E-mail: jori.uusitalo@luke.fi

article id 195, category Research article

John R. Moore, Andrew J. Lyon, Gregory J. Searles, Leena E. Vihermaa. (2009). The effects of site and stand factors on the tree and wood quality of Sitka spruce growing in the United Kingdom. Silva Fennica vol. 43 no. 3 article id 195. https://doi.org/10.14214/sf.195

Keywords: wood quality; acoustics; timber properties; wood stiffness

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The extent and sources of variation in the wood quality of Sitka spruce (Picea sitchensis (Bong.) Carr.) were quantified using data collected from 64 stands in northern Britain. These stands were selected on the basis of elevation, latitude, longitude, yield class, initial spacing and the presence or absence of thinning. Dynamic modulus of elasticity (MOE) was calculated from measurements of stress wave velocity made on standing trees and qualitative descriptions were made of stem form. Dynamic MOE of individual trees ranged from 3.81 kN/mm² up to 12.29 kN/mm², with a mean of 7.71 kN/mm². Approximately 55 percent of the variation in dynamic MOE was due to differences between individual trees within a site, while 35 percent was due to differences between sites. The remaining 10 percent was due to differences between the measurements made on opposite sides of each tree. Variation in dynamic MOE at the site level was significantly influenced by yield class, elevation as well as by a number of the interactions between these factors and latitude, longitude and initial spacing. A multiple regression model incorporating these variables was able to explain 45 percent of the variation in dynamic MOE. Ramicorn branches were the most commonly recorded defect (37.2% of all live trees), followed by stem scarring and basal sweep (6.9% and 6.3%, respectively). Dynamic MOE was not influenced by stem straightness (p = 0.10) which indicates the utility of stress wave velocity measurements for segregating Sitka spruce stands based on potential grade recovery.

Moore, Centre for Timber Engineering, Napier University, 10 Colinton Road, Edinburgh EH10 5DT, United Kingdom E-mail: j.moore@napier.ac.uk
Lyon, Centre for Timber Engineering, Napier University, 10 Colinton Road, Edinburgh EH10 5DT, United Kingdom E-mail: ajl@nn.uk
Searles, Centre for Timber Engineering, Napier University, 10 Colinton Road, Edinburgh EH10 5DT, United Kingdom E-mail: gjs@nn.uk
Vihermaa, Department of Analytical and Environmental Chemistry, University of Glasgow, Glasgow, UK E-mail: lev@nn.uk

article id 221, category Research article

Glen Murphy, Rod Brownlie, Mark Kimberley, Peter Beets. (2009). Impacts of forest harvesting related soil disturbance on end-of-rotation wood quality and quantity in a New Zealand radiata pine forest. Silva Fennica vol. 43 no. 1 article id 221. https://doi.org/10.14214/sf.221

Keywords: Pinus radiata; harvesting; compaction; wood density; tree growth; stiffness; litter removal; nitrogen deficiency

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The long-term effect of soil disturbance (litter removal, topsoil removal and compaction) from forest harvesting on wood quality and quantity of second-rotation Pinus radiata growing on a clay loam soil, was assessed at the end the rotation, 26 years after planting. Relative to Control plots, average tree and stand total volume at rotation end was not significantly affected by litter removal and nil or light compaction, but was significantly reduced by 28% by litter and topsoil removal and moderate subsoil compaction, and further reduced by 38% by heavy compaction. Wood density at breast height in the inner rings of trees in the most disturbed treatments was elevated by up to 30 kg m^–3. This occurred because these treatments were more N deficient as reflected by foliar N levels during the first 11 years of growth relative to the Control. However, no treatment differences in wood density were evident in outer rings, and by rotation age overall mean density did not differ significantly between treatments. Neither acoustic velocity of standing trees, nor acoustic velocity of logs, was significantly affected by soil disturbance, indicating that stiffness of lumber cut from trees in the trial was likely to be similar for all treatments. Economic impacts of soil disturbance and compaction on this soil type will therefore result largely from the considerable negative impacts on final tree size, with little or no compensation from improved wood properties.

Murphy, Forest Engineering, Resources and Management Department, Oregon State University, Corvallis, Oregon, USA E-mail: glen.murphy@oregonstate.edu
Brownlie, Scion Research, Rotorua, New Zealand E-mail: rb@nn.nz
Kimberley, Scion Research, Rotorua, New Zealand E-mail: mk@nn.nz
Beets, Scion Research, Rotorua, New Zealand E-mail: pb@nn.nz

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