Generic and specific stem volume models for three subtropical forest types in southern Brazil

Abstract

& Methods Data from 418 sample plots were used to adjust generic models for forest types and specific models for 15 species. Regression assumptions, modelling efficiency, lack of fitness, goodness of fit and comparison between species-specific and generic models were assessed by analytical methods. & Results Logarithmic models presented the best results of adjustment and evenness of residual variance. Lack of fit F test showed acceptable adjust quality for nearly all speciesspecific and generic models; R 2 adj * and modelling efficiency measure presented values close to 1 for all fitted models; model identity F test showed differences between specific and generic models in some cases. & Conclusion Since regression assumptions were satisfied and because of their quality of fit, the fitted models compose useful tools for predicting total stem volume (with bark) for forest remnants in southern Brazil. Stratification of datasets by forest type for model fitting showed to be necessary, but, commonly, generic models for forest types produced estimates not less reliable than species-specific models.

Tree Height Reduction After Selective Logging in a Tropical Forest

“…Henceforth, bole height is a widely used measure in forestry to estimate the commercial volume of tree stems ( e.g ., Vibrans et al . ).…”

“…While small unreiterated or epicormics branches may still be found below crown base (Nicolini et al 2003, Barth el emy & Caraglio 2007, these branches do not affect timber quality and were hence disregarded. Henceforth, bole height is a widely used measure in forestry to estimate the commercial volume of tree stems (e.g., Vibrans et al 2015).…”

Robust volumetric models for supporting the management of secondary forest stands in the Southern Brazilian Atlantic Forest

“…However, legal restrictions and operational constraints in protected native forests may forbid the harvesting of trees, thus impeding data collection. A usual workaround is sampling collection by means of tree climbing, yet a viable alternative to gather stem volume data (e.g., Vibrans et al 2015). Partly, this could be the explanation for the scarcity of total tree volume models for the Atlantic Forest subdomains in Brazil.…”

Lumber volume modeling of Amazon Brazilian species

“…Logarithmic models are often used in Brazil, especially in different forests in the Amazon (Silva & Santana, 2014), although very few studies have applied the transformation back from the log-log scale to the original scale using the corrective factor (Sprugel, 1983;Vibrans, Moser, Oliveira, & de Maçaneiro, 2015). In addition, R 2 is often used to describe the fit quality of the model; however, very few studies have calculated the R 2 for transformed data back (or original scale), evidencing a misleading use of R 2 , since it has limitations of use in non-linear models (Anderson-Sprecher, 1994;Tellinghuisen & Bolster, 2011;Vibrans et al, 2015). Other parameters such as RMSE and Bias are rarely calculated based on the original scale of the residues.…”