An analysis of spatial forest structure using neighbourhood-based variables

Aguirre, Oscar; Gao, Hui; Gadow, Klaus von; Jiménez, Josefina

doi:10.1016/s0378-1127(03)00102-6

Cited by 195 publications

(152 citation statements)

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“…K(d) was calculated from the equation: (1) where λ is the density of stems per unit area, d ij the distance from tree i to tree j, and n the number of trees in a circular area of radius d. The K value is compared to the expected value of a Poisson distribution obtained through 99 simulations of the Poisson process [25]. Discarding the 2.5% higher and lower values of the 99 simulations we can establish also a 95% confidence bounds.…”

Section: Stand Structure Characterisationmentioning

confidence: 99%

“…The spatial pattern was also analysed using Gadow's uniform angle index [12]: (3) where n is the number of neighbours considered (in this case n = 3), w ij is the angle formed by the two lines issued from a reference tree and going through i and j neighbours and w is the ratio of 360º to n. If stems were very uniformly distributed, w ij should be more wide than under clumped distribution, so I Gi = 1 indicates that the trees in the neighbourhood of the reference tree are clumped, I Gi = 0 indicates a regular distribution of trees [1].…”

Section: Stand Structure Characterisationmentioning

confidence: 99%

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The effects of thinning on the structural diversity of coppice forests

Montes¹,

Cañellas²,

Rı́o³

et al. 2004

Ann. For. Sci.

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-Coppices are currently at a turning point: traditional uses have been abandoned and silviculture must be redefined according to new uses. Thinning to improve the development of trees is often the silvicultural treatment chosen. This paper attempts to assess the changes in forest structural diversity induced by different thinning regimes applied in coppice stands of Quercus pyrenaica and Quercus faginea. Structural diversity is analysed through spatial pattern, crown dimensions, vertical and horizontal differentiation and foliage height diversity. Moderate and heavy thinning have similar effects on stand structure, but the effects of light thinning are quite different for both species. The spatial pattern shows a greater regularity as the intensity of the thinning regime increases. The response of Q. pyrenaica to thinning is noticeable both in tree height and crown diameter, whilst in the case of Q. faginea, trees reacted to thinning by developing epicormic sprouts on the stem from the base of the crown. Vertical differentiation shows opposite trends in both species: increasing the intensity of thinning leads to an increase in vertical differentiation with Q. pyrenaica, but to a greater homogenisation shortly after thinning with Q. faginea. A neighbourhood analysis using Gadow's differentiation index is able to provide useful information on the changes in microstructure, while foliage height diversity index can be used to describe complex changes in the vertical structure of the stand. coppice / Quercus pyrenaica / Quercus faginea / structural diversity / thinning Résumé -L'effet des éclaircies sur la diversité structurale des taillis. Aujourd'hui, les taillis se trouvent à une phase de changement : on a renoncé à leur usage traditionnel, et alors la sylviculture est obligée de les redéfinir selon les nouveaux usage qu'on propose. Le recours aux éclaircies pour améliorer le croissance des arbres est le traitement de préférence. Ce travail a pour but l'identification des changements qui se sont produits dans la diversité structurale du peuplement, et qui ont été induits par l'application des divers types d'éclaircies sur les taillis de Quercus pyrenaica y Quercus faginea. La diversité structurale est étudiée avec l'analyse du modèle de répartition des tiges, de la taille des cimes, de la différenciation tant horizontale que verticale et des variations de hauteur du feuillage. Les éclaircies moyennes et fortes ont à peu près le même effet sur la structure du peuplement, mais l'effet des éclaircies plus légères est bien différent dans les deux espèces. Le modèle spatial montre une plus grande régularité au fur et à mesure que l'intensité de l'éclaircie augmente. La réponse de Quercus pyrenaica à l'éclaircie est bien évidente tant en ce qui concerne la croissance en hauteur que le diamètre de la cime. Mais pour Quercus faginea, les arbres vont réagir d'une autre façon, avec l'émission de bourgeons adventifs dès la partie inférieure de la couronne. La différenciation verticale va montrer deux tendances diffé...

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Section: Stand Structure Characterisationmentioning

confidence: 99%

Section: Stand Structure Characterisationmentioning

confidence: 99%

The effects of thinning on the structural diversity of coppice forests

Montes¹,

Cañellas²,

Rı́o³

et al. 2004

Ann. For. Sci.

View full text Add to dashboard Cite

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“…The index values of trees in the strip along the crest line of a ridge were calculated by means of the following formulas (Eqs. 1 and 2) Aguirre et al 2003;). The mean value of all trees was then calculated to find the total diversity value of each landscape.…”

Section: Calculation Of Form Diversity and Height Dominance Indicesmentioning

confidence: 98%

“…Many indices have been developed to assess structural diversity (Shannon and Weaver 1949;Simpson 1949;Clark and Evans 1954;Holdridge 1967;Gadow et al 1998;Aguirre et al 2003;Ozdemir and Karnieli 2011). However, a neighbour-based index will more accurately reflect the landscape effect of neighbouring trees within the immediate vicinity of a reference point (tree).…”

Section: Calculation Of Form Diversity and Height Dominance Indicesmentioning

confidence: 99%

Assessment of landscape silhouette value in urban forests based on structural diversity indices

Özkan

Özdemir

2015

Int. J. Environ. Sci. Technol.

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Urban forests form an important component of the urban environment. They make a significant contribution to landscape silhouettes due to species diversity and the differences observed within forest communities such as tree composition, size and form. Visual effects such as these are referred as aesthetic value. Therein, quantitative assessments of targeted forest structures that will optimize aesthetic values are vital during urban forest planning. However, the silhouette effect, which is an important component of aesthetic value, has not been extensively studied to date. This study aims to reveal the relationship between forest structure, the visual quality of tree composition and the different forms and sizes that create the silhouette effect. To this end, virtual landscapes of different structures were created using computer-assisted images. The forest structure was characterized by a Form Mingling Index (FMI) and Height Dominance Index (HDI). A Pearson correlation was applied in order to find the relationship between the landscape silhouette values through a perceptual test as well as the FMI and HDI. The results of the analyses showed that there was a strong positive relationship between the FMI and HDI (r = 0.78, r = 0.75, P \ 0.01, respectively) and landscape silhouette values. The combined effect of FMI ? HDI was found to have the highest relationship with landscape silhouette values (r = 0.80, P \ 0.01). In conclusion, FMI and HDI offer a rapid, cost-effective method which can be used by managers to assess the silhouette value of an urban forest landscape.

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“…In addition, sampling design allows integration of this dataset with other ones available from previous studies (e.g. Aguirre et al 2003;Hui and Pommerening 2014;LeMay et al 2009), useful for comparative, large-scale studies. The data allowed a traditional set of forest parameters to be extracted like stand variables (stocking rate, basal area, species composition, dominant height, mean diameter).…”

Section: Reuse Potential and Limitsmentioning

confidence: 99%