294 2010 Biomechanics Week event prevented collection of a larger data set, and this may have influenced the ability to gain clear comparative differences within the testing groups. Also, with more time and funding, finer detail in branching character and cross-sectional shape profile and area data could have been developed. While the replication is low and the final results are not definitive, it is important to remember that the trees which were destructively har- vested were standing and in sound condition and selected to make the specific observational comparisons. Too often we can only observe failed trees and make inferences with- out having information from trees which did not fail, since it takes decades (over 50 years in this case) to develop a testing block from which to attempt this study. In general, there were no observations of specific growth shape profiles such as T-beam or I-beam/figure-eight roots as noted in other works (Nicoll and Ray 1996; Coutts et al. 1999; Weber and Mattheck 2005). However, it is important to note those studies were looking at gymnosperms in the Pinaceae, whereas this study used species in the Sapinda- ceae with very different wood organization and vascular tissue differences. A generally greater ZRT and UBT dis- tance was observed from the trees in the 2016 Acer rubrum harvest as compared to the 2010 Acer saccharinum. The study’s observations are certainly consistent with a pattern of growth which is influential on load transfers in the redirection from trunk to roots. While the data set is too small to yield any conclusive observations, it is interesting in the 2016 Acer rubrum harvest to observe plantation-edge windward roots have a slightly shorter UBT distance with thicker roots on average. Coupled with the anastomosis effect and rapid branching of the windward roots, any con- sideration of the influence of the collective (or aggregated) root geometry demonstrates the importance of dimensional size, which would contribute to an argument of added stiff- ness (Coutts 1987) with a caveat that the external surface of the root belies a potentially discontinuous volume of heterogeneous tissue structure rather than a material. As a pattern of nonconcentric radial growth, the study’s observations were consistent with a tensile loading empha- sis. This finding is further bolstered by a generally short (within a single section thickness) downward bias, to the point of no observation prior to concentric root develop- ment and associated loss of taper. The differences in UBT comparing the perpendicular roots to the windward and leeward roots in the 2010 silver maples are consistent with the observations of Nicoll and Dunn (2000) insomuch as the roots perpendicular to the wind were different than those in the windward/leeward orientation. It supports a notion that the flexing of roots (compression down and a pulling outward) produces a difference in growth patterns from the roots if perpendicular to a prevailing wind. Urban trees can be seen to have impacts from specific wind ©2019 International Society of Arboriculture Grabosky et al.: Wind Load Influence on Root Growth Dissymmetry directions in a designed space, or take wind from any direction if planted as an isolated specimen rather than in a more natural grove configuration. With that view, the data could be helpful in future studies to frame the design and observation methods for future opportunities. While sectioning did not go down to an anatomic anal- ysis, observations from both harvests in the gross scale are consistent with observations in tissue organization and morphology discussed in Christensen-Dalsgaard et al. (2008), where growth in proximal zones of the buttress roots is highly mechanically loaded from initial growth, whereas further out, the mechanical loads become less influential during early tree growth stages. That influence further out on the root increases progressively over years of growth of the tree above ground, both in the change in trunk proxim- ity with growth, and with the stature of the tree and its interception of wind. ACKNOWLEDGEMENTS Thanks to Allyson Salisbury and Pam Zipse for their efforts and assistance in developing and supervising students in the Rutgers Urban Forestry Group resulting in this manu- script. The following persons were instrumental in collecting roots and processing root sections as field technicians or as students in the Rutgers Urban Forestry Lab Group: Irene Donne, Ward Peterson, Alan Siewert, Stephanie Foster- Miller, Mark J. Hoenigman and his group from Busy Bee Services Ltd., Bernie Car and Son from Organic Air, Josh Caplan, Matt McKinney, Jake Spooner, Gregory Dahle, and Jess Sanders. Also, many thanks to ISA, The TREE Fund, Rinn Tech, Bartlett Tree Experts, Davey Tree Com- pany, and other sponsors of the Biomechanics Week events. Funding from the John and Eleanor Kuser Faculty endowment for Urban Forestry and varied McIntire Sten- nis projects over the years have helped with students under urban forestry project grants. LITERATURE CITED Barker, P. 1989. Tree root and sidewalk conflicts. pp. 15-19. In: P. Rodbell (Ed.). Make Our Cities Safe for Trees: Proceedings of the Fourth Urban Forestry Conference. National Urban Forest Council. Christensen-Dalsgaard, K.K., A.R. Ennos, and M. Fournier. 2008. Are radial changes in vascular anatomy mechanically induced or an ageing process? Evidence from observations on buttressed tree root systems. Trees 22(4): 543-550. Costello, L.R., and K.S. Jones. 2003. Reducing Infrastructure Damage by Tree Roots: A Compendium of Strategies. West- ern Chapter of the International Society of Arboriculture (WCISA), Porterville, California, U.S.A. pp. 6-21. Coutts, M.P. 1983. Root architecture and tree stability. Plant and Soil 71(1-3): 171-188. Coutts, M.P. 1987. Developmental processes in tree root systems. Canadian Journal of Forest Research 17(8): 761-767.
November 2019
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
