Tree crown architecture and ice accretion

Despite a longstanding interest in tree species’ vulnerability to ice storms, analyses of the influence of crown structure on within-crown variation in ice accretion are rare. Nock et al. test the hypothesis that intra-crown ice accretion can be predicted by a measure of sheltering by neighbouring branches. Empirical results and simulations confirmed a key role for crown architecture in determining intra-crown ice accretion.

Simulated tree from a functional–structural modelling suite.
Simulated tree from a functional–structural modelling suite. Using the freezing rain simulation tool IceTree, we have simulated a freezing rain event. Simulated ice accretion on branches of secondary branching order of the simulated tree showing covariation between SF (α = 10 cm, β = 10°) and ice accretion. Colour gradients (scale on the figure) show: (A) the simulated radial ice accretion (mm), and (B) SF. Image by Nock et al. (2016).

As suspected, droplets are attenuated by passage through the crown, and thus higher branches accumulate more ice. This is the first step in developing a modelling approach to investigating intra-crown and inter-specific variation in freezing rain damage.

Reference List

Charles A. Nock, Bastien Lecigne, Olivier Taugourdeau, David F. Greene, Jean Dauzat, Sylvain Delagrange, Christian Messier, 2016, 'Linking ice accretion and crown structure: towards a model of the effect of freezing rain on tree canopies', Annals of Botany, vol. 117, no. 7, pp. 1163-1173 http://dx.doi.org/10.1093/aob/mcw059