Equations for estimating loblolly pine branch and foliage weight and surface area distributions

Abstract

Equations to predict foliage weight and surface area, and their vertical and horizontal distributions, within the crowns of unthinned loblolly pine (Pinus taeda L.) trees are presented. A right-truncated Weibull function was used for describing vertical foliage distributions. This function ensures that all of the foliage located between the tree tip and the foliage base is included. Foliage distribution prediction is based on actual two-dimensional foliage location. It is shown that the average time of full foliage, and hence average foliage weight or surface area prediction, is highly variable for loblolly pine and subject to considerable error. To help account for the old and new foliage differences during the approximate time of "full leaf," the prediction equations for new and old foliage weight and surface area include a day-of-year term. New equations to predict branch weight, surface area, and the vertical distributions of branch biomass and surface area were also developed. The vertical distributions of branch biomass and surface area are described with logarithmic equations constrained to equal zero when relative crown depth is equal to zero, and to equal one when relative crown depth is one.Résumé : Les auteurs présentent des équations qui servent à prédire le poids et la surface du feuillage ainsi que sa distribution verticale et horizontale dans la cime de pins à encens (Pinus taeda L.) non éclaircis. Une fonction de Weibull tronquée à droite a été utilisée pour décrire la distribution verticale du feuillage. Cette fonction assure que tout le feuillage situé entre l'extrémité et la base de la cime soit inclus. La prédiction de la distribution du feuillage est basée sur sa localisation actuelle selon deux dimensions. Il est démontré, qu'en moyenne, le moment où le feuillage est complet est très variable et que, par conséquent, la prédiction du poids ou de la surface du feuillage dans le cas du pin à encens est sujette à d'importantes erreurs. Afin d'aider à tenir compte des différences entre le vieux et le nouveau feuillages pendant la période approximative où le feuillage est complet, les équations de prédiction pour le poids et la surface du jeune et du vieux feuillages comportent un terme pour le jour de l'année. De nouvelles équations capables de prédire le poids des branches, la surface et la distribution verticale de la surface et de la biomasse des branches, ont également été développées. La distribution verticale de la surface et de la biomasse des branches est décrite par des équations logarithmiques dont la valeur est égale à zéro lorsque la profondeur relative de la cime est égale à zéro et à un lorsque la profondeur relative de la cime est égale à un. [Traduit par la Rédaction]

Estimating Leaf Bulk Density Distribution in a Tree Canopy Using Terrestrial LiDAR and a Straightforward Calibration Procedure

“…More complete allometric equations, that include crown dimension, competition, stand age, basal area, management practices, etc. are robust between sites [13][14][15], but requires a much larger data collection that in the present study. For the reasons stated below, the LiDAR calibration for a given species or group of species could be much more robust.…”

“…At forest plot scale, a common method, hereinafter referred to as the inventory-based approach, is to combine a stem inventory and allometric equations for biomass and its vertical cumulative distribution in order to estimate leaf load and bulk density profile [12,13]. However, in order to be robust, allometric equations require significant sampling since leaf biomass does not only vary with stem diameter, but also with crown dimension, competition, stand age, basal area, management practices and even day in the year [13][14][15]. Sensitivity to type of equation for vertical distribution may also be high [13].…”

“…However, in order to be robust, allometric equations require significant sampling since leaf biomass does not only vary with stem diameter, but also with crown dimension, competition, stand age, basal area, management practices and even day in the year [13][14][15]. Sensitivity to type of equation for vertical distribution may also be high [13]. Remote sensing techniques have long been used in forest management and research, especially for estimating leaf area index [16].…”

Canopy fuel characteristics and potential crown fire behavior in Aleppo pine (Pinus halepensis Mill.) forests

“…Nevertheless, current research efforts state that in certain fuel complexes, other fuel categories, such as the fine twigs, may significantly contribute to the heat released from the flaming zone of a crown fire [19,70,76]. Although numerous studies correlate crown or foliage biomass with tree dendrometric characteristics [13,37,46,51,53,55,56], only few studies measure crown fuel load by diameter size class at tree level [15,39,40,73] and at stand level [9,23], as it is required in crown fire behavior modeling.…”

Pr�diction de la biomasse a�rienne d'Acacia cyanophylla Lindl. (Syn. A. saligna (Labill.) H. Wendl) � partir de mensurations dimensionnelles

“…Ce qui explique la rareté des évalua-tions tentées dans les comptes rendus des divers projets ou les travaux de recherche. En effet, ces méthodes d'évaluation constituent dans la plupart des cas un bon moyen de prédiction de la biomasse ligneuse et feuillue des arbres et arbustes [3,4,6,13,29]. L'objectif de cette étude est d'établir des modèles de régression permettant de prédire la biomasse aérienne d'Acacia cyanophylla Lindl.…”