VOLUME AND TAPER EQUATIONS FOR COMMERCIAL STEMS OF Nothofagus obliqua AND N. alpina

Abstract

Timber volume of standing trees is essential information for management decisions. The increasing need to optimize the potential capacity of forests maintaining their conservation, requires the quantification of the different potential possible timber products. The aim was to adjust taper equations to determine volumes of different timber products for commercial stems of Nothofagus alpina and N. obliqua. Trees of both species were randomly selected in harvesting areas of Lanin National Park (Argentina). Trees were felled and cut into commercial logs, measuring diameter with bark at different heights up to the beginning of the crown, and for each tree the diameter at breast height and total height. Five taper equations were selected and non-linear regression processes were employed for the fittings. We obtained the volume through the integration of the stem profile equation and the rotation in the space thereof through solid of revolution. The Bennet and Swindel (1972) model was selected for both Nothofagus species, obtaining similar equation parameters and differences were observed at the top of the stems of larger trees. For this the use of an integrated model is not recommended. With the obtained equations it is possible to: (i) estimate volume at different heights and for different commercial diameters, and (ii) predict the height at which both species reach to a certain diameter. The model presented some statistical limitations (e.g. multicollinearity), however, the fitting of the equation and the easy understanding of the outputs support it as a useful tool in a broad range of forest applications. EQUAÇÕES DE AFILAMENTO E VOLUME PARA TAMANHOS COMERCIAIS DE Nothofagus obliqua E N. alpinaRESUMO: O volume de madeira das árvores em pé é uma informação essencial para as decisões de gestão. A crescente necessidade de otimizar a capacidade potencial das florestas mantendo sua conservação, requer a quantificação dos diferentes possíveis produtos de madeira possíveis. O objetivo era ajustar equações de afilamento para determinar volumes de diferentes produtos de madeira para hastes comerciais de Nothofagus alpina e N. obliqua. As árvores de ambas as espécies foram selecionadas ao acaso nas áreas de colheita do Parque Nacional Lanin (Argentina). As árvores foram derrubadas e cortadas em troncos comerciais, medindo o diâmetro com a casca em diferentes alturas até o início da coroa, e para cada árvore o diâmetro na altura do peito e altura total. Foram selecionadas cinco equações cônicas e foram empregados processos de regressão não-linear para ajustar. Obtivemos o volume através da integração da equação do perfil do caule e da rotação no seu espaço através do sólido da revolução. O modelo de Bennet e Swindel (1972) foi selecionado para as duas espécies de Nothofagus, obtendo parâmetros de equação semelhantes e observando-se diferenças no topo das hastes de árvores maiores. Portanto, o uso de um modelo integrado não é recomendado. Com as equações obtidas é possível: (i) estimar o volume em diferentes alturas ...

Semi-empirical estimation of log taper using stem profile equations

“…In that case, the statistical background for nonlinear least squares is violated, thus ordinary least-squares regression can result in the bias of parameter estimates. Many recent studies have proved the advantage of mixed-effect modelling to deal with the problem of highly correlated data (e.g., Yang et al 2009;Beltran et al 2017;Adamec et al 2019). According to Burkhart and Tomé (2012), one of the solutions to overcome the problem of multicollinearity is to reduce the number of variables.…”

“…Science, 67, 2021 (7): 318-327 Original Paper https://doi.org/10.17221/209/2020-JFS few of them are focused on log taper (Larsen 2017;Clutter 1980). It is also worth noting that the use of stem taper equations that describe a gradual decrease in diameters along the stem (West 2015;Beltran et al 2017) can be complicated due to the need of diameter at breast height (DBH) and stem height measurements for each felled tree. The complexity of stem taper models limits their use during the round wood volume estimation, however modelling stem profiles provides necessary input data for the further calculation of log taper that are harvested from different parts of the stem.…”

Efeito de variáveis de copa em funções de afilamento

“…Diante disso, Beltran et al (2017) relatam que diferente da floresta plantada, a nativa dificilmente fornece perfeição teórica para as equações, uma vez que possui maior heterogeneidade que pode ser atribuída as irregularidades do perfil do fuste das árvores. Nesse sentido, deve-se ressaltar que no presente trabalho os indivíduos de X. brasiliensis se encontram estabelecidos em um fragmento típico de floresta nativa, sofrendo as influências de todo o ambiente ao redor, em competição contínua com outros indivíduos por espaço, luz e nutrientes.…”

Serratia strains isolated from the rhizosphere of raulí ( Nothofagus alpina ) in volcanic soils harbour PGPR mechanisms and promote raulí plantlet growth

“…Oerst. (= N. nervosa) commonly known as raulí, is an endemic tree species of subantarctic deciduous-temperate forests (Donoso et al, 2006;Beltran et al, 2017). Raulí is a species that can reach up to 3 m in diameter and 35-40 m in height.…”

“…Overall, raulí has the potential to become one of the most important commercial forestry species in Chile (Beltran et al, 2017).…”