Estimation of crown radii and crown projection area from stem size 
and tree position

Grote, Rüdiger

doi:10.1051/forest:2003031

Cited by 49 publications

(39 citation statements)

References 35 publications

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“…We have focused on obtaining a good spatial distribution of the total crown volume at a local scale and have not validated our approach by directly comparing modelled crowns to real ones, and only tested if the simulated stands with reconstructed crowns gave good results in the light model. An approach similar to the CROM algorithm has been proposed by Grote [32] in which potential crown radius is predicted from stem diameter without using crown volume, and by managing overlaps in a simpler way than in the CROM algorithm. In this work, validation is made in terms of crown geometry and shows a strong correlation of crown projection areas with measured ones but poor prediction for particular radii.…”

Section: Discussionmentioning

confidence: 99%

Reconstructing crown shape from stem diameter and tree position to supply light models. I. Algorithms and comparison of light simulations

et al. 2005

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-Light models provide an interesting way to analyse the influence of the forest canopy on understory biological processes but need a detailed description of tree crowns, requiring many field measurements. This study proposes supplying light models with only stem diameter and tree position and reconstructing crowns using diameter-related allometric relations. First, the diameter-related relations for total height, crown base height and mean crown radius were established for each species. Second, two reconstruction methods were compared: a simple isotropic method and a more sophisticated method, the Crown Reconstruction by Overlap Minimisation method. The latter method gave better results than the simpler one, even if some small bias was not completely resolved in the darkest areas. However, using crown centre position instead of stem position resolved this bias. crown reconstruction / crown competition / light model / heterogeneous forest / broadleavesRésumé -Reconstruction de la forme des houppiers à partir du diamètre des arbres et de leur position pour alimenter un modèle de lumière. I. Algorithmes et comparaison des simulations de l'éclairement. Les modèles de lumière constituent un bon moyen pour analyser l'influence du couvert forestier sur les processus biologiques sous-couvert. Malheureusement ils nécessitent une description détaillée des houppiers des arbres, ce qui implique des mesures de terrain assez lourdes. Cet article propose d'alimenter les modèles de lumière uniquement avec le diamètre et la position des arbres, et de reconstituer les houppiers en utilisant des relations allométriques en fonction du diamètre à 1,30 m. Les relations allométriques sont tout d'abord établies pour la hauteur totale, la hauteur de base de houppier et le rayon moyen du houppier, pour chaque espèce. Ensuite deux méthodes de reconstruction des houppiers sont comparées : une méthode simple dite isotrope et une plus sophistiquée, la méthode de reconstruction des houppiers par minimisation des chevauchements. Cette dernière donne de meilleurs résultats, même si un léger biais subsiste dans les zones les plus sombres. Cependant le fait d'utiliser la position des centres de houppiers au lieu de celle des troncs permet de complètement supprimer ce biais. reconstruction des houppiers / compétition des houppiers / modèles de lumière / forêt hétérogène / feuillus

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Section: Discussionmentioning

confidence: 99%

Reconstructing crown shape from stem diameter and tree position to supply light models. I. Algorithms and comparison of light simulations

et al. 2005

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“…With an estimated maximum diameter of the fine root system of 20 m (Carpinus and Tilia) to 40 m (Fagus and Acer), trees of these species may spread their fine roots over an area of ca. 300 m 2 and up to 1,200 m 2 , which is roughly 5-20 times the size of the corresponding crown projection area (Frech et al 2003;Utschig and Küsters 2003;Grote 2003;Hemery et al 2005;Frech 2006). While Hölscher et al (2002) found a maximum horizontal extension of only ca.…”

Section: Horizontal Fine Root Distribution and Species Overlapmentioning

confidence: 99%

No evidence of spatial root system segregation and elevated fine root biomass in multi-species temperate broad-leaved forests

Meinen

Leuschner

Ryan

et al. 2009

Trees

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Differences in spatial rooting patterns among coexisting species have been recognized as an important mechanism for generating biodiversity effects on ecosystem functioning. However, it is not yet clear whether complementarity in root space exploration is a universal characteristic of multi-species woody communities. In a temperate broad-leaved forest with a mosaic of speciespoor and species-rich stands, we tested two hypotheses related to putative below-ground 'overyielding' in more diverse forests, (1) that species mixture results in a partial spatial segregation of the fine root systems of different species, and (2) that stand fine root biomass increases with tree species diversity. We investigated 12 stands either with one, three, or five dominant tree species (4 replicate stands each) under similar soil and climate conditions for stand fine root biomass and spatial root segregation in vertical and horizontal direction in the soil. Fine roots of different tree species were identified using a morphological key based on differences in colour, periderm surface structure, and branching patterns. In species-poor and species-rich stands, and in all tree species present, fine root density (biomass per soil volume) decreased exponentially with soil depth at very similar rates. Stand fine root biomass in the densely rooted upper soil (0-40 cm depth) was not significantly different between stands with 1, 3 or 5 dominant tree species. We conclude that 'below-ground overyielding' in terms of higher fine root biomasses in species-rich stands as compared to monospecific ones does not occur in these broad-leaved forests which most likely results from a missing complementarity in vertical rooting patterns of the present tree species.

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“…Nowadays, allometric models are a common method for the estimation of CPA based on easily measurable proxy variables like basal area (BA) [30].…”

Section: Allometric Modelsmentioning

confidence: 99%

“…• , and 315 • ) were measured for a total of 132 trees located in the center of the stand using the "tangential-look-up-method" (tangentiale Hochblickmethode) [13,30] in winter 2016/17. Crown radii measurements were independently repeated by three persons to assess possible inter-observer bias.…”

Section: Data Collectionmentioning

confidence: 99%

Automatic Assessment of Crown Projection Area on Single Trees and Stand-Level, Based on Three-Dimensional Point Clouds Derived from Terrestrial Laser-Scanning

Ritter

Nothdurft

2018

Forests

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Abstract:Crown projection area (CPA) is a critical parameter in assessing inter-tree competition and estimating biomass volume. A multi-layer seeded region growing-based approach to the fully automated assessment of CPA based on 3D-point-clouds derived from terrestrial laser scanning (TLS) is presented. Independently repeated manual CPA-measurements in a subset of the stand serve as the reference and enable quantification of the inter-observer bias. Allometric models are used to predict CPA for the whole stand and are compared to the TLS-based estimates on the single tree-and stand-level. It is shown that for single trees, the deviation between CPA measurements derived from TLS data and manual measurements is on par with the deviations between manual measurements by different observers. The inter-observer bias propagates into the allometric models, resulting in a high uncertainty of the derived estimates at tree-level. Comparing the allometric models to the TLS measurements at stand-level reveals the high influence of crown morphology, which only can be taken into account by the TLS measurements and not by the allometric models.

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Estimation of crown radii and crown projection area from stem size and tree position

Cited by 49 publications

References 35 publications

Reconstructing crown shape from stem diameter and tree position to supply light models. I. Algorithms and comparison of light simulations

Reconstructing crown shape from stem diameter and tree position to supply light models. I. Algorithms and comparison of light simulations

No evidence of spatial root system segregation and elevated fine root biomass in multi-species temperate broad-leaved forests

Automatic Assessment of Crown Projection Area on Single Trees and Stand-Level, Based on Three-Dimensional Point Clouds Derived from Terrestrial Laser-Scanning

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