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

Seidel, Dominik; Leuschner, Christoph; Müller, Annika; Krause, Benjamin

doi:10.1016/j.foreco.2011.03.008

Cited by 112 publications

(104 citation statements)

References 37 publications

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“…Interspecific competition can also have a strong impact on crown structure (Bayer et al, 2013) and crown allometry . In this regard the study of crown plasticity by terrestrial laser scanning is a promising tool (Seidel et al, 2011;Metz et al, 2013).…”

Section: Species Interaction and Species Richness -Ecosystem Functioningmentioning

confidence: 99%

European Mixed Forests: definition and research perspectives

et al. 2014

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Aim of study: We aim at (i) developing a reference definition of mixed forests in order to harmonize comparative research in mixed forests and (ii) review the research perspectives in mixed forests.Area of study: The definition is developed in Europe but can be tested worldwide.Material and Methods: Review of existent definitions of mixed forests based and literature review encompassing dynamics, management and economic valuation of mixed forests.Main results: A mixed forest is defined as a forest unit, excluding linear formations, where at least two tree species coexist at any developmental stage, sharing common resources (light, water, and/or soil nutrients). The presence of each of the component species is normally quantified as a proportion of the number of stems or of basal area, although volume, biomass or canopy cover as well as proportions by occupied stand area may be used for specific objectives. A variety of structures and patterns of mixtures can occur, and the interactions between the component species and their relative proportions may change over time.The research perspectives identified are (i) species interactions and responses to hazards, (ii) the concept of maximum density in mixed forests, (iii) conversion of monocultures to mixed-species forest and (iv) economic valuation of ecosystem services provided by mixed forests.Research highlights: The definition is considered a high-level one which encompasses previous attempts to define mixed forests. Current fields of research indicate that gradient studies, experimental design approaches, and model simulations are key topics providing new research opportunities.Keywords: COST Action; EuMIXFOR; mixed-species forests; admixtures of species.

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Section: Species Interaction and Species Richness -Ecosystem Functioningmentioning

confidence: 99%

European Mixed Forests: definition and research perspectives

et al. 2014

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“…Nevertheless, we used the index of tangents, as it provides additional information, specifically a relationship between tree height and crown radius (distance of regular crown), which varies under different stocking densities. The intensity of the competition pressure is determined by the height and distance of the competing tree from the standard, canopy height and crown distance (Seidel et al 2011). We identified the strongest competitor in both sets by correlating the distance and height of different tree species with the index of crown compression (ratio of tangents), and evaluated whether height or distance of the competitor were more important.…”

Section: Discussionmentioning

confidence: 99%

“…In both sets, ash (F. excelsior) is the main competitor. Ash has more rapid height growth than its neighbours (Seidel et al 2011) and often occupies the upper storey or overstorey (Getzin et al 2008). The overstorey trees experience very low competition in the canopy but they act as competitors to their neighbours.…”

Section: Discussionmentioning

confidence: 99%

“…Crown parameters, relationships between crowns and other mensurational data (Hasenauer 1997;Rouvinen, Kuuluvainen 1997;Nilsson et al 2002;Webster, Lorimer 2003;Longuetaud et al 2008) as well as the influence of competitors on crown irregularity have been investigated in many studies, but mainly in high forests (Osada et al 2004;Getzin, Wiegand 2007;Getzin et al 2008;Seidel et al 2011). It was also noted that tree and crown competition indices are different for modelling competition between individual trees, and for the competition pressure of the entire stand (Fabrika, Pretzsch 2013).…”

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confidence: 99%

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Crowns of "forgotten" standards in hardwood floodplain forests

Šálek¹,

Machar²,

Sıvacıoğlu³

et al. 2017

J. For. Sci.

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AbstractŠálek L., Machar I., Sivacioğlu A., Zahradník D., Simon J., Jeřábková L. (2017): Crowns of "forgotten" standards in hardwood floodplain forests. J. For. Sci., 63: 538-548.Floodplain forests have traditionally been managed using the coppice-with-standards silvicultural system for centuries. After abandoning this silvicultural system approximately in the 1950s the crown of standards (mature-aged trees) developed gradually under the growing influence of their tree competitors. This study examines the crowns of remnant oak and ash standards in a hardwood floodplain forest along the Morava River in the Czech Republic. 100 oak (Quercus robur Linnaeus) standards and 100 ash (Fraxinus excelsior Linnaeus) standards were randomly selected and the basic mensuration data as well as some ecological data, such as number of large dead branches, cavities, and height of the lowest large dead and green branches, were measured. The four nearest neighbour competitors were identified for each standard, and their height, distance and azimuth were measured. The DBH of the analysed oak standards ranged between 71 and 148 cm, and the projected oak crown area ranged between 125 and 533 m 2 . The ash DBH ranged between 71 and 127 cm, and projected ash crowns between 194 and 620 m 2 . To assess competitive pressure, we calculated an index as a ratio of the tangents of angles of regular and compressed crowns. Distance of competing trees was more important than their height in the ash data set, but not in the oak data set.

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“…However, similar to the α‐value, the voxel size has to be chosen with care as it can have a significant effect on the measured property, in particular when computing volumes. With respect to tree crowns, voxel grids have been used to compute leaf area index and foliage (Béland, Widlowski, Fournier, Côté, & Verstraete, 2011), crown plasticity (Seidel, Leuschner, Müller, & Krause, 2011), crown competition (Metz et al., 2013), and CVs (Fernández‐Sarría et al., 2013; Metz et al., 2013). Often, α‐shape and voxel grid approaches are used in combination (Fernández‐Sarría et al., 2013; Metz et al., 2013; Seidel et al., 2011), mainly because they enable faster point cloud processing and simplification.…”

Section: Introductionmentioning

confidence: 99%

A high‐resolution approach for the spatiotemporal analysis of forest canopy space using terrestrial laser scanning data

Hess

Härdtle

Kunz

et al. 2018

Ecology and Evolution

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Forest canopies and tree crown structures are of high ecological importance. Measuring canopies and crowns by direct inventory methods is time‐consuming and of limited accuracy. High‐resolution inventory tools, in particular terrestrial laser scanning (TLS), is able to overcome these limitations and obtain three‐dimensional (3D) structural information about the canopy with a very high level of detail. The main objective of this study was to introduce a novel method to analyze spatiotemporal dynamics in canopy occupancy at the individual tree and local neighborhood level using high‐resolution 3D TLS data. For the analyses, a voxel grid approach was applied. The tree crowns were modeled through the combination of two approaches: the encasement of all crown points with a 3D α‐shape, which was then converted into a voxel grid, and the direct voxelization of the crown points. We show that canopy occupancy at individual tree level can be quantified as the crown volume occupied only by the respective tree or shared with neighboring trees. At the local neighborhood level, our method enables the precise determination of the extent of canopy space filling, the identification of tree–tree interactions, and the analysis of complementary space use. Using multitemporal TLS data recordings, this method allows the precise detection and quantification of changes in canopy occupancy through time. The method is applicable to a wide range of investigations in forest ecology research, including the study of tree diversity effects on forest productivity or growing space analyses for optimal tree growth. Due to the high accuracy of this novel method, it facilitates the precise analyses even of highly plastic individual tree crowns and, thus, the realistic representation of forest canopies. Moreover, our voxel grid framework is flexible enough to allow for the inclusion of further biotic and abiotic variables relevant to complex analyses of forest canopy dynamics.

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

Cited by 112 publications

References 37 publications

European Mixed Forests: definition and research perspectives

European Mixed Forests: definition and research perspectives

Crowns of "forgotten" standards in hardwood floodplain forests

A high‐resolution approach for the spatiotemporal analysis of forest canopy space using terrestrial laser scanning data

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