Seeing the Wood in the Trees: Unleashing the Secrets of Wood via near Infrared Spectroscopy

ISSn: 0967-0335 © IM publications llp 2011 doi: 10.1255/jnirs.913 all rights reserved forests and forest products play a major economic role in the world with global Gdp topping uS$45 trillion in 2005 (1% of global Gdp) and this is projected to reach uS$100 trillion by 2030.1 In a world of diminishing resources where deforestation of natural forests is of global concern, plantation forests, which globally cover 140 million ha, provide a sustainable approach to ensuring a continued supply of traditional building materials and, with the advent of emerging technologies, developing novel fuels, speciality chemicals and nano-crystalline cellulose, all of which will play a vital role in shaping our future society and economy. Wood and biomass are now regarded as renewable resources that can partially alleviate reliance on petrochemicals for every day needs and at the same time sequester carbon from the atmosphere to reduce atmospheric co2 levels. the transition from utilisation of natural forests to a plantation forest resource is, however, not without some problems. In many cases the drive to plantation forests is regulatory and in others it is through sheer need, as access to natural forests decline. processors, however, frequently maintain that the plantation logs are not the same as what they used to be. In many respects they are correct: the logs are often younger, smaller diameter and of greatly differing wood properties. the wealth of knowledge that has been established over a considerable period of time for the natural forest resource must now be replaced with new knowledge for the plantation forest resource—but the pressure of time requires this information to be available immediately. In current wood processing and manufacturing operations, knowledge of wood characteristics and the measurement of those characteristics are essential to ensure optimal utilisation. In order to accurately control the product quality before or during processing, there is the need to have a system which is capable of real-time monitoring of wood properties. one emerging technology that could fill the gap for wood and wood processing measurements is advanced vibrational spectroscopy, particularly near infrared (nIr) spectroscopy. It has been 20 years since Birkett and Gambino2 first reported the use of nIr to estimate the lignin content of wood pulps and Wright, Birkett and Gambino3 predicted the pulp yield and cellulose content of wood. Since then, a flurry of activity has taken place and many wood–nIr applications have been explored. It is timely to reflect on what this activity has achieved in the last 20 years and, importantly, to highlight some of the issues that still need to be overcome in order to further promote the utilisation and application of nIr in the forest and forest products industry. the earliest studies concentrated on wood properties directly related to wood chemistry and were based on milled chips obtained from composite whole-tree samples. the range of applications rapidly expanded and nIr was used to estimate the moisture content and basic density of intact chips, the physical and mechanical properties (mainly stiffness and strength) of solid wood, the characteristics of chemical pulps, and the density, microfibril angle and stiffness of radial strips Guest editorial Seeing the wood in the trees: unleashing the secrets of wood via near infrared spectroscopy