Spatial pattern of subalpine forest-alpine grassland ecotones in the Spanish Central Pyrenees

Camarero, J. Julio; Gutiérrez, Emília; Fortin, Marie‐Josée

doi:10.1016/s0378-1127(99)00241-8

Cited by 99 publications

(97 citation statements)

References 63 publications

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“…In the L m (d) analysis for plot V1, it can be seen that, when the young cohorts develop in small gaps, the asymmetric competition from the larger tree strata leads to a higher structural heterogeneity in the young cohort. The height heterogeneity added to the cluster pattern at short scales in plot V8, similar to that found in other studies at the altitudinal tree line (Camarero et al 2000), may be due to the smothering effect provided by the windward neighbours. This effect allays the extreme, high-altitude conditions within the cluster and results in ''wave regeneration'' (Satō and Iwasa 1993), which seems to favour regeneration performance in the vicinity of the established tree groups.…”

Section: Discussionsupporting

confidence: 86%

Evaluating height structure in Scots pine forests using marked point processes

et al. 2008

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Abstract:In this study, the second-moment analysis of marked spatial point processes is applied to the characterization of the tree height distribution in two Scots pine (Pinus sylvestris L.) forests in the Central Mountain Range of Spain. The cumulative function Lm(d) weighted by the normalized mark variance is proposed to analyse the second-order properties of marked point patterns. The empirical Lm(d) was compared with two null models to assess the relationship between the spatial distribution of the trees and the tree height correlations: the first null model was used to characterize the spatial clustering of the trees and was derived from the complete spatial randomness model used with Ripley's K(d) function. The second null model, which is derived from the random labelling model used with the intertype second-moment measure K12(d) (type 1 intensity conditioned to the type 2 intensity and vice versa), allows us to identify the mark correlations. The performance of the technique was assessed through simulated marked point patterns. The second-moment analysis showed that most of the analysed Scots pine stands have a uniform height distribution at small scale and greater heterogeneity at large scales, with the exception of an upper altitudinal stand, which exhibited heterogeneity at short distances. These results demonstrate the utility of second-moment analysis of marked point processes for characterizing height structure in forest stands and the interaction between the height and the spatial pattern of the trees.Résumé : Dans cette étude, l'analyse du moment de second ordre des processus ponctuels marqués est utilisée pour caractériser la distribution des hauteurs d'arbre dans deux forêts de pin sylvestre (Pinus sylvestris L.) situées dans la cordillère centrale en Espagne. La fonction cumulative L m (d) pondérée par la variance normalisée est proposée pour analyser les propriétés du moment de second ordre des structures spatiales. La fonction empirique L m (d) est comparée à deux modèles de référence pour évaluer la relation entre la distribution spatiale des arbres et les corrélations entre les hauteurs d'arbre. Le premier modèle de référence, dérivé du modèle spatial entièrement aléatoire basé sur la fonction de Ripley K(d), est utilisé pour caractériser le regroupement spatial des arbres. Le deuxième modèle de référence, dérivé du modèle de marquage aléatoire utilisé avec la mesure inter type du moment de second ordre K 12 (d) (intensité de type 1 conditionnelle à l'intensité de type 2 et vice-versa), permet d'identifier les corrélations. La performance de la technique est évaluée par l'intermé-diaire des structures spatiales simulées. L'analyse du moment de second ordre montre que la plupart des peuplements de pin sylvestre analysés présentent une distribution uniforme des hauteurs à petite échelle et une plus grande hétéro-généité à grande échelle, à l'exception d'un peuplement situé à plus haute altitude dont l'hétérogénéité se manifeste sur de courtes distances. Ces résultats démontrent l'utilité de ...

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Section: Discussionsupporting

confidence: 86%

Evaluating height structure in Scots pine forests using marked point processes

et al. 2008

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“…Most of all, the role of Gotjawal terrain in terms of creating extremely diverse microhabitats, and subsequently, stochastic processes of survival or mortality of trees need to be emphasized. In stressful habitats such as the rocky coasts and alpine forests, spatial structure largely depends on constraining factors such as topography and disturbances (Camarero et al 2000;Scarano 2002;Humphries et al 2008). If so, we can draw a couple of inferences regarding the ecological role of Gotjawal terrain.…”

Section: Influence Of the Rocky Gotjawal Terrainmentioning

confidence: 99%

Spatial distribution patterns of old-growth forest of dioecious tree Torreya nucifera in rocky Gotjawal terrain of Jeju Island, South Korea

Shin

Lee²,

Kang

2017

j ecology environ

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Background: Spatial structure of plants in a population reflects complex interactions of ecological and evolutionary processes. For dioecious plants, differences in reproduction cost between sexes and sizes might affect their spatial distribution. Abiotic heterogeneity may also affect adaptation activities, and result in a unique spatial structure of the population. Thus, we examined sex-and size-related spatial distributions of old-growth forest of dioecious tree Torreya nucifera in extremely heterogeneous Gotjawal terrain of Jeju Island, South Korea. Methods: We generated a database of location, sex, and size (DBH) of T. nucifera trees for each quadrat (160 × 300 m) in each of the three sites previously defined (quadrat A, B, C in Site I, II, and III, respectively). T. nucifera trees were categorized into eight groups based on sex (males vs. females), size (small vs. large trees), and sex by size (small vs. large males, and small vs. large females) for spatial point pattern analysis. Univariate and bivariate spatial analyses were conducted. Results: Univariate spatial analysis showed that spatial patterns of T. nucifera trees differed among the three quadrats. In quadrat A, individual trees showed random distribution at all scales regardless of sex and size groups. When assessing univariate patterns for sex by size groups in quadrat B, small males and small females were distributed randomly at all scales whereas large males and large females were clumped. All groups in quadrat C were clustered at short distances but the pattern changed as distance was increased. Bivariate spatial analyses testing the association between sex and size groups showed that spatial segregation occurred only in quadrat C. Males and females were spatially independent at all scales. However, after controlling for size, males and females were spatially separated. Conclusions: Diverse spatial patterns of T. nucifera trees across the three sites within the Torreya Forest imply that adaptive explanations are not sufficient for understanding spatial structure in this old-growth forest. If so, the role of Gotjawal terrain in terms of creating extremely diverse microhabitats and subsequently stochastic processes of survival and mortality of trees, both of which ultimately determine spatial patterns, needs to be further examined.

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“…Para los dos límites del bosque de P. uncinata antes mencionados (Ordesa, Tessó), Camarero et al (2000) calcularon correlogramas de Mantel omnidireccionales usando un conjunto de variables estructurales (diáme-tros basal y normal, altura, etc.) para distintos tipos de individuos clasificados según su forma (arbustivo, arbóreo) y tamaño (plántula, vástago, joven y adulto).…”

Section: Dutilleulunclassified

Spatial surface-pattern analyses and boundary detection techniques applied in forest ecology

Camarero

Rozas

2006

For. syst.

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ResumenEn este trabajo se revisan los métodos de análisis univariable y multivariable de los patrones de superficies y de detección de fronteras más utilizados en ecología forestal. El patrón de superficies es un patrón espacial continuo definido por las posiciones de los puntos (árboles) en el espacio y una o varias variables asociadas a cada punto. Se ilustran métodos útiles para describir patrones espaciales e inferir los procesos que los generaron. Se muestra el fundamento estadístico y ejemplos aplicados de métodos de análisis univariables para variables binarias (conteo contiguo) y cuantitativas (correlogramas de Moran y Geary, semivariogramas, dimensión fractal). Se detalla el cálculo e interpretación de métodos multivariables para la descripción de patrones de superficies (correlograma y test de Mantel) y su relación con los métodos de ordenación. Finalmente, se muestran ejemplos de métodos para la detección de fronteras. La mayor parte de los patrones reales analizados provienen de bosques de Pinus uncinata del límite altitudinal superior en los Pirineos o bien de una población relíctica. Se discuten las ventajas y desventajas de cada metodología y sus aplicaciones en ecología forestal.Palabras clave: autocorrelación espacial, correlograma, semivariograma, ordenación, fronteras Abstract Spatial surface-pattern analyses and boundary detection techniques applied in forest ecologyWe review methods for uni-and multivariate surface pattern analysis and boundary detection used in forest ecology. A continuous surface pattern is defined as the locations of points (trees) in the space and the associated variable or variables. We illustrate useful methods to describe spatial patterns and infer the generating processes. We show the statistical basis and applied examples of univariate methods for binary (join counts) and quantitative variables (Moran and Geary correlograms, semivariograms, fractal dimension). We explain the calculus and interpretation of multivariate methods to describe surface patterns (Mantel test and correlogram) and their relationships with ordination methods. Finally, we show examples of techniques for boundary detection. Most analysed patterns corresponded to Pinus uncinata forests from the upper altitudinal limit in the Pyrenees or from a relict population. We discuss the advantages and disadvantages of each methodology and their applications in forest ecology.

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Spatial pattern of subalpine forest-alpine grassland ecotones in the Spanish Central Pyrenees

Cited by 99 publications

References 63 publications

Evaluating height structure in Scots pine forests using marked point processes

Evaluating height structure in Scots pine forests using marked point processes

Spatial distribution patterns of old-growth forest of dioecious tree Torreya nucifera in rocky Gotjawal terrain of Jeju Island, South Korea

Spatial surface-pattern analyses and boundary detection techniques applied in forest ecology

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