The anatomy and grain pattern in forks of hazel (Corylus avellana L.) and other tree species

Fracture properties of green wood formed within the forks of hazel (Corylus avellana L.)

“…The fracture surfaces of the samples were also examined using the scanning electron microscopy technique (SEM) to determine the influence of wood anatomy and microstructure on the failure patterns and toughening mechanism of specimens. The forks of hazel were studied particularly, because this study was carried out in conjunction with the previous studies by Slater and Ennos 2013, Slater et al 2014and Buckley et al 2015 which investigated the strength and failure mode properties of hazel forks in detailed. Together those previous studies, this research will provide broad understanding in the mechanism of tree forks.…”

“…Note that the route of each grain line passes from the parent stem into one or other arising branch, ensuring all sap-conducting routes run from 'source to sink' as they should. b Schematic diagram of the arrangement of the piths (yellow), vessels (blue), fibres (white), and rays (red) at a fork in Corylus avellana (Slater et al 2014) Fig. 3 Fracture systems in wood normal to the crack plane and the second letter "radial" refers to the direction of crack propagation) (Ashby et al 1985).…”

“…Several researchers, therefore, have sought to determine why and how forks failure and how they can be assessed for their risk of failure (MacDaniels 1923(MacDaniels -1932Miller 1959;Shigo 1985;Harris 1992;Hauer et al 1993;Matheny and Clark 1994;Farrell 2003;Smiley 2003;Kane 2007;Kane et al 2008;Ennos 2013, 2015;Slater et al 2014). In the previous studies, branch-trunk diameter ratio and branch angle have primarily been investigated to identify the best predictor for a fork's strength.…”

“…To date, several studies have mainly concentrated on the structural strength of tree forks, to explain how and why forks fail and how they develop a best-fit adaptation to lessen the risk of tree failure (MacDaniels 1932;Miller 1959;Shigo 1985;Harris 1992;Hauer et al 1993;Lilly and Sydnor 1995;Farrell 2003;Smiley 2003;Kane 2007;Kane et al 2008;Ennos 2013, 2015;Slater et al 2014;Buckley et al 2015). However, there is lack of knowledge concerning the fracture mechanism around the tree forks.…”

“…From the results, they concluded that the load-bearing capacity of the forks was mostly obtained from the central apex regions of bifurcations, with the central xylem contributing 35%, the peripheral regions, 50%, while resistance to bending of the wood contributed only around 15%. To determine why this was the case, Slater et al (2014) examined the anatomy and grain pattern in tree forks. Their anatomical analyses showed that centrally placed xylem at the apex of the bifurcation had more tortuous and interlocked wood grain than wood elsewhere.…”