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Comparison of SilviScan and optical imaging measurements of tracheid dimensions and wood density

Formally Refereed

Abstract

SilviScan uses X-ray transmission measurements along with optical imaging to profile tracheid dimensions and wood density in specially prepared cores. These measurements are useful for predicting the properties of pulp and paper generated from the wood. SilviScan measurements are resolution-limited by the width of the X-ray beam, which was 50 m in the present study. Trees with growth rings smaller than 200 m have latewood regions too small to measure without sampling adjacent earlywood, producing erroneous latewood measurements. For these suppressed-growth trees, we developed an all-optical imaging approach called Ring Profiler to contrast with SilviScan. Ring Profiler uses higher magnification than SilviScan, allowing direct measurement of tracheid wall thicknesses. Ring Profiler showed that SilviScan overestimated latewood tracheid radial diameters by as much as 100% in growth rings under 200- m width. It also showed that SilviScan underestimated density of suppressed-growth latewood by 15-20%. Use of higher magnification limits Ring Profiler’s measurements to fewer tracheids than SilviScan’s (3% as many in the present study). Ring Profiler lacks the ability of SilviScan to measure microfibral angle by means of X-ray diffraction, and density measurement by Ring Profiler is indirect. Otherwise, all dimensional information provided by SilviScan can be generated at higher resolution using widely available optical imaging technology.

Keywords

Douglas fir, wood density, pulping, image analysis, wood anatomy, tracheary cells, latewood, earlywood, thinnings, pulpwood, Ring Profiler, small-diameter timber, smallwood, stand density, SilviScan, tracheids, suppressed growth, small timbers, utilization

Citation

Vahey, David W.; Zhu, Junyong; Scott, C. Tim. 2006. Comparison of SilviScan and optical imaging measurements of tracheid dimensions and wood density. Proceedings of 2006 Progress in Paper Physics, 2006 October 1-5, Oxford, OH. Oxford, OH : Miami University, 2006: pages 73-76.
https://www.fs.usda.gov/research/treesearch/33695