On simplifying allometric analyses of forest biomass

Biomass Modeling of Larch (Larix spp.) Plantations in China Based on the Mixed Model, Dummy Variable Model, and Bayesian Hierarchical Model

“…West et al [46] applied a process-based model which is called the WBE model, to estimate values of scaling exponents using a functional relationship; it indicated that the aboveground biomass of a tree species should scale against stem diameter with b = 8/3 (2.67), regardless of species, site, and age. However, Zianis and Mencuccini [12] estimated another empirical exponent (b = 2.36) based on a worldwide list of 279 biomass allometric equations, which is different from the scaling exponent (b ≈ 2.67). They indicated that the ratio of biomass and DBH for trees growing in different environmental conditions cannot be constant.…”

“…Allometric equations have been widely used to estimate forest biomass in many studies, but the use of allometric equations in regions outside the area in which they were developed or for different species, has been strongly debated in forestry literature. Some authors have even recommended using general allometric equations [12,13]. In this study, the scaling coefficient in allometric equations was varied in different biomass components (stem wood, branches, stem bark, needle, root and total biomass), and across different larch species and regions.…”

“…In this study, the scaling coefficient in allometric equations was varied in different biomass components (stem wood, branches, stem bark, needle, root and total biomass), and across different larch species and regions. Although it is generally known that the scaling exponent b is between two and three [12], it is also usually realized as a species-specific equation, with different coefficients a and b, because trees may differ in architecture as well as wood density [6,45]. West et al [46] applied a process-based model which is called the WBE model, to estimate values of scaling exponents using a functional relationship; it indicated that the aboveground biomass of a tree species should scale against stem diameter with b = 8/3 (2.67), regardless of species, site, and age.…”

On the geometry and allometry of big-buttressed trees - a challenge for forest monitoring: new insights from 3D-modeling with terrestrial laser scanning

“…Tree variables commonly used for such models are the diameter at breast height (DBH, measured at 1.3 m height) or DBH in combination with total tree height. These allometric relationships (from the ancient Greek word "αλλος" = "other") are commonly modeled as power functions (Niklas 1994, West et al 1999a, Zianis & Mencuccini 2004, Pilli et al 2006, Fehrmann & Kleinn 2006 of the form M = aDb, where M is the mass of dry matter, D is the diameter, b is the allometric scaling factor and a is a coefficient determining the allometric intercept (Parresol 1999). The general model formulation also complies with assumptions of process models in plant allometry that are based on considerations on the hydraulic architecture and structural design of vascular plants and derive a particular scaling exponent of 8/3 (West et al 1997, 1999a, 1999b, Enquist 2002, Niklas 2004.…”

Inventory data usage in carbon stock assessment for targeting Kyoto protocol requests

“…D'altro canto, la scala temporale, normalmente superiore al decennio, e la disomogenea distribuzione spaziale dei rilievi dendrometrici nelle particelle, possono rendere inutilizzabili dati preziosi, quali la distribuzione diametrica e la composizione del soprassuolo che, opportunamente impiegati, potrebbero fornire una stima dettagliata dello stock di carbonio presente in foresta mediante l'applicazione di coefficienti di espansione o di equazioni allometriche (Schroeder et al 1997, Joosten et al 2004. Queste ultime, in particolare, consentirebbero di stimare non solo la massa assestamentale, ma la stessa biomassa arborea totale (almeno a livello epigeo), attraverso la conoscenza della sola distribuzione diametrica del popolamento (Zianis & Mencuccini 2004). L'impiego di equazioni allometriche risulta tuttavia ostacolato sia dal fatto che in molte particelle vi è solo una stima visiva dei principali parametri dendro-auxometrici, sia dalla difficoltà di confrontare seriazioni spesso rilevate in anni diversi nelle particelle in cui è stato effettuato un rilievo relascopico o un cavallettamento.…”