Crown plasticity in mixed forests—Quantifying asymmetry as a measure of competition using terrestrial laser scanning

By D. Seidel, Christoph Leuschner, Annika Müller, B. Krause. 2011

126 citations recorded by the source corpus.

Abstract Interspecific competition is a key process determining the dynamics of mixed forest stands and influencing the yield of multispecies tree plantations. Trees can respond to competitive pressure from neighbors by crown plasticity, thereby avoiding competition. We employed a high-resolution ground-based laser scanner to analyze the 3-dimensional extensions and shape of the tree crowns in a near-natural broad-leaved mixed forest in order to quantify the direction and degree of crown asymmetry of 15 trees (Fagus sylvatica, Fraxinus excelsior, Carpinus betulus) in detail. We also scanned the direct neighbors and analyzed the distance of their crown centres and the crown shape with the aim to predict the crown asymmetry of the focal tree from competition-relevant attributes of its neighbors. It was found that the combination of two parameters, one summarizing the size of the neighbor (DBH) and one describing the distance to the neighbor tree (HD), was most suitable for characterizing the strength of the competitive interaction exerted on a target tree by a given neighbor. By summing up the virtual competitive pressure of all neighbors in a single competitive pressure vector, we were able to predict the direction of crown asymmetry of the focal tree with an accuracy of 96° on the full circle (360°). The competitive pressure model was equally applicable to beech, ash and hornbeam trees and may generate valuable insight into competitive interactions among tree crowns in mixed stands, provided that sufficiently precise data on the shape and position of the tree crowns is available. Multiple-aspect laser-scanning proved to be an accurate and practicable approach for analyzing the complex 3-dimensional shape of the tree crowns, needed to quantify the plasticity of growth processes in the canopy. We conclude that the laser-based analysis of crown plasticity offers the opportunity to achieve a better understanding of the dynamics of canopy space exploration and also may produce valuable advice for the silvicultural management of mixed stands.

Subfields: Environmental Engineering, Mechanical Engineering, Nature and Landscape Conservation

View Paper: https://www.semanticscholar.org/paper/d106520e93c0381285520938a9a2c53f45880448

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Citations in the corpus

Comparison and Combination of Mobile and Terrestrial Laser Scanning for Natural Forest Inventories (2018, background): “Overlapping crowns and regions of interactions of an individual tree with its neighbors are detected by determining the intersection of alpha-shapes [51,52].”
Crown plasticity enables trees to optimize canopy packing in mixed-species forests (2015, background): “Although canopy packing (as defined above) is inherently related to the cumulative leaf area of trees within a plot, the two measures will not necessarily covary perfectly as leaf density can vary strongly within crowns (e.g., Seidel et al. 2011b).”
Response of sugar maple (Acer saccharum, Marsh.) tree crown structure to competition in pure versus mixed stands (2016, methodology): “Several authors have shown that this ability is partly explained by the position of the bigger and closer competitor using competition indices based on individual competitor tree metrics (DBH, height, CPA) (Brisson, 2001; Muth and Bazzaz, 2003; Schröter et al., 2012; Seidel et al., 2011a).”