Angle of inclination affects the morphology and strength of bifurcations in hazel (Corylus avellanaL.)

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.…”

“…A number of researchers have reported that the attachment angle is the most closely related to the strength of attachment (MacDaniels 1923;Ruth and Kelley 1932;Verner 1955;Buckley et al 2015); however, others found no relationship between branch angle and strength of bifurcation (MacDaniels 1932;Lilly and Sydnor 1995;Gilman 2003;Pfisterer 2003;Kane 2007). On the other hand, some researchers have indicated that the strength of the junction was mainly correlated with an increase in the branch-trunk diameter ratio (MacDaniels 1932;Miller 1959;Shigo 1985;Farrell 2003;Gilman 2003;Kane 2007;Kane et al 2008;Buckley et al 2015) in such a way that relatively larger forces were required to pull apart narrow branches attached to thick ones; forks with branches of equal diameter were considered weakest (Matheny and Clark 1994;Gilman 2003;Kane et al 2008). In a more recent study, Buckley et al (2015) showed that diameter ratio of branch and branch strength was significantly correlated with each other, but there was a significant negative relationship, in that, higher diameter ratio of the branches failed at lower breaking stresses.…”

“…On the other hand, some researchers have indicated that the strength of the junction was mainly correlated with an increase in the branch-trunk diameter ratio (MacDaniels 1932;Miller 1959;Shigo 1985;Farrell 2003;Gilman 2003;Kane 2007;Kane et al 2008;Buckley et al 2015) in such a way that relatively larger forces were required to pull apart narrow branches attached to thick ones; forks with branches of equal diameter were considered weakest (Matheny and Clark 1994;Gilman 2003;Kane et al 2008). In a more recent study, Buckley et al (2015) showed that diameter ratio of branch and branch strength was significantly correlated with each other, but there was a significant negative relationship, in that, higher diameter ratio of the branches failed at lower breaking stresses. A study by Slater and Ennos (2013) also found that diameter ratio is also an important parameter affecting how the forks fail.…”

“…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.…”

Examining Strain Propagation in the Lateral and Codominant Branch Attachment Using Digital Image Correlation

“…The angle of branch attachment has long been thought to be an indicator of attachment strength, especially by practitioners. Yet numerous studies have shown that the angle of branch in relation to the stem has little to do with the strength of that attachment (MacDaniels 1932;Miller 1959;Lilly and Sydnor 1995;Gilman 2003;Pfisterer 2003;Kane 2007;Buckley et al 2015). In a large study of red maple (Acer rubrum), callery pear (Pyrus calleryana), and sawtooth oak (Quercus acutissima) by Farrell (2003), several structural features were examined to explain differences in branch connection strength.…”