REVIEW Literature review of acoustic and ultrasonic tomography in standing trees Andre ´s Arciniegas • Flavio Prieto • Loı ¨c Brancheriau • Philippe Lasaygues Received: 17 September 2013 / Revised: 22 February 2014 / Accepted: 28 July 2014 / Published online: 6 August 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Key message High-resolution imaging is possible if high-frequency sensors are used together with a signal- processing and inversion algorithm that is well suited to a low signal-to-noise ratio and the effect of wood anisotropy. Abstract Wood is a biological growth medium, and given that standing trees adapt themselves in their growth to environmental conditions, their material properties vary with age. These changes result in variations that are far more complex than anisotropy. Wood quality and intra- specific variability can thus be studied to gain an under- standing of the development mechanisms of trees, and this can be useful for clonal selection and the management of tree communities. A number of techniques are available to determine wood properties in standing trees, but the signal- processing approaches currently used are not always robust and do not always provide the image resolution needed in the particular cases of acoustic or ultrasonic tomography. This review paper thus aims to present important aspects that should be taken into account when using tomography techniques and addresses a number of open problems. A brief review of current non-destructive wood imaging techniques is initially presented followed by a comparison of the protocols, methods and models used in acoustic and ultrasonic tomography. The devices cited were studied in terms of measurement systems and signal processing. The analysis aimed to highlight and analyze the advantages and disadvantages of each device and describe challenges and trends. The effect of various parameters is discussed: fre- quency, signal-to-noise ratio, number of sensors and inversion algorithm. General conclusions are then drawn in relation to future signal-processing work in the acoustic and ultrasonic tomography of standing trees. Keywords Wood quality  Imaging  Acoustics  Tomography  Signal processing Introduction Twigs, branches, and the entire tree react to optimize access to light, implement a genetically determined geometry and maintain the mechanical stability of the tree in the face of external forces (e.g., wind) and gravity (development plasticity). Plant tissues, particularly the buds, are sensitive to light stimuli, gravity and mechanical stress (Fournier et al. 2006). Wood matter in the tree is therefore always preloaded, with specific prestresses being distributed according to location in terms of height and diameter. The accumulation of successive layers of matter also responds to a number of growth mechanisms that create considerable differences in the structure and the physical and mechanical properties of wood between the pith and the bark (juvenility, heartwood formation, tem- poral evolution of properties). Wood quality and intraspe- cific variability in standing trees can thus be studied to gain an understanding of the mechanisms of tree development (structural development and shape, biological functioning) Communicated by R. Matyssek. A. Arciniegas (&)  P. Lasaygues CNRS, LMA UPR 7051, Marseille, France e-mail: arciniegas@lma.cnrs-mrs.fr F. Prieto Universidad Nacional de Colombia, Bogota ´, Colombia L. Brancheriau CIRAD, UR BioWooEB–UMR AMAP, Montpellier, France 123 Trees (2014) 28:1559–1567 DOI 10.1007/s00468-014-1062-6