Goodman, Rosa
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
Research article2019Peer reviewedOpen access
Jackson, T.; Shenkin, A.; Moore, J.; Bunce, A.; van Emmerik, T.; Kane, B.; Burcham, D.; James, K.; Selker, J.; Calders, K.; Origo, N.; Disney, M.; Burt, A.; Wilkes, P.; Raumonen, P.; Menaca, J. Gonzalez de Tanago; Lau, A.; Herold, M.; Goodman, R. C.; Fourcaud, T.; Malhi, Y.
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The relationship between form and function in trees is the subject of a long-standing debate in forest ecology and provides the basis for theories concerning forest ecosystem structure and metabolism. Trees interact with the wind in a dynamic manner and exhibit natural sway frequencies and damping processes that are important in understanding wind damage. Tree-wind dynamics are related to tree architecture, but this relationship is not well understood. We present a comprehensive view of natural sway frequencies in trees by compiling a dataset of field measurement spanning conifers and broadleaves, tropical and temperate forests. The field data show that a cantilever beam approximation adequately predicts the fundamental frequency of conifers, but not that of broadleaf trees. We also use structurally detailed tree dynamics simulations to test fundamental assumptions underpinning models of natural frequencies in trees. We model the dynamic properties of greater than 1000 trees using a finite-element approach based on accurate three-dimensional model trees derived from terrestrial laser scanning data. We show that (1) residual variation, the variation not explained by the cantilever beam approximation, in fundamental frequencies of broadleaf trees is driven by their architecture; (2) slender trees behave like a simple pendulum, with a single natural frequency dominating their motion, which makes them vulnerable to wind damage and (3) the presence of leaves decreases both the fundamental frequency and the damping ratio. These findings demonstrate the value of new three-dimensional measurements for understanding wind impacts on trees and suggest new directions for improving our understanding of tree dynamics from conifer plantations to natural forests.
natural frequencies; fundamental frequency; tree architecture; terrestrial laser scanning; finite-element analysis; wind damage
Interface
2019, Volume: 16, number: 155, article number: 20190116Publisher: ROYAL SOC
Forest Science
DOI: https://doi.org/10.1098/rsif.2019.0116
https://res.slu.se/id/publ/101007