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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2016

To document

Abstract

Black locust, poplar and spruce samples were steamed at 80°C and 120°C for 48 hours. IR difference spectra and the CIE Lab colour coordinates were measured for determining the chemical changes caused by the steaming. Steaming at 80°C caused only small changes in both IR spectra and colour. But steaming at 120°C produced intensive colour change and well-visible changes in IR spectra. The guaiacyl lignin in hardwoods underwent slight degradation but in spruce suffered substantial degradation during steaming at 120°C. The syringyl lignin absorbing around 1600 cm−1 did not show any changes, indicating that it is more stable to steaming than guaiacyl lignin. The absorption decrease at 1175 cm−1 indicated the cleavage of ether linkage in cellulose and hemicelluloses at both steaming temperatures.

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Abstract

There is evidence that recently occurring top dieback of Norway spruce (Picea abies (L.) Karsten) tress in southern Norway is associated with drought stress. We compared functional wood traits of 20 healthy looking trees and 20 trees with visual signs of top dieback. SilviScan technology was applied to measure cell dimensions (lumen and cell wall thickness) in a selected set of trunk wood specimens where vulnerability to cavitation (P50) data were available. The wall/lumen ratio ((t/b)²) was a quite good proxy for P50. Cell dimensions were measured on wood cores of all 40 trees; theoretical vulnerability of single annual rings could be thus estimated. Declining trees tended to have lower (t/b)² before and during a period of water deficit (difference between precipitation and potential evapotranspiration) that lasted from 2004 to 2006. The results are discussed with respect to genetic predisposition.