Potential of Pinus radiata plantations for use of harvest residues in characteristic soils of south-central Chile

Abstract

Given the growing demand for harvest residues for energy generation from Pinus radiata forest plantations in south-central Chile, models for estimating site-specific forest residue production are needed. In this study, allometric models were fitted to estimate the potential biomass resulting from the harvest of P. radiata plantations located in volcanic sand, recent volcanic ash and sedimentary soils, taking into consideration management gradients and site productivity, in characteristic sites of south-central Chile. The fitted models allowed estimating conversion factors and developing estimation models at individual tree and stand level. Results suggest that conversion factors for changing from stem biomass to potential residue biomass have a negative exponential relationship with tree size. Models fitted for estimating at individual tree level, starting with diameter and height variables, suggest that the models depend on soil origin, while in the case of stand-level estimates the fitted model is independent of soil origin, gradient management and productivity.Resumen D ada la demanda creciente sobre los residuos de cosecha para la generación de energía en plantaciones forestales de Pinus radiata en la zona centro-sur de Chile, resulta necesario disponer de modelos que permitan la estimación sitio-específico de la producción de residuos. En este estudio se realizó el ajuste de modelos alométricos de estimación de la biomasa potencial de residuos de cosecha para plantaciones de P. radiata, en suelos de arenas volcánicas, cenizas volcánicas recientes y sedimentarios, considerando gradientes de manejo y productividad, en sitios característicos del centro-sur de Chile. Los modelos ajustados permitieron la estimación de factores de conversión, y modelos de estimación a nivel de árbol individual y rodal. Los resultados sugieren que los factores de conversión de biomasa fustal a biomasa potencial de residuos tienen una relación exponencial negativa con el tamaño de los individuos. Los modelos ajustados para la estimación a nivel de árbol individual, a partir de las variables diámetro y altura, sugieren que los modelos dependen del origen del suelo, mientras que para el caso de las estimaciones a nivel de rodal, el modelo ajustado resulta independiente del origen del suelo, gradiente de manejo y su productividad. Palabras clave: Biomasa aérea, biomasa y bioenergía, residuos, modelos de biomasa, factores de conversión de biomasa.

Additive predictions of aboveground stand biomass in commercial logs and harvest residues for rotation age Pinus radiata plantations in New South Wales, Australia

“…These differences in the method of harvesting, in the composition of harvest residues, and in the drying temperature of biomass samples could lead to differences in the predicted residue biomass. For the same stand basal area, the predicted harvest residue biomass in dry weight from the simple linear relationship of Cartes-Rodríguez et al (2016) was on average more than 60% greater than what was predicted by the systems of equations developed in this study.…”

“…As the cut-to-length harvesting yields significantly higher levels of residue than the traditional whole-tree or tree-length harvesting (Ghaffariyan et al 2012Ghaffariyan and Apolit 2015), the systems of equations developed here are only applicable to plantations with similar log specifications and harvesting methods. A case in point is the simple linear relationship between the potential harvest residue biomass in dry weight and stand basal area reported by Cartes-Rodríguez et al (2016) for P. radiata plantations in south-central Chile. They destructively sampled 250 trees from 27 stands with stand basal areas over a range similar to that of the 61 plots in this study.…”

Product and Residue Biomass Equations for Individual Trees in Rotation Age Pinus radiata Stands under Three Thinning Regimes in New South Wales, Australia

“…It should be noted that trees in T2 stands had lower percentages of residue biomass than those in unthinned and T1 stands. These percentages were within the broad range of values reported by Madgwick and Webber [44], Ximenes et al [45] and Cartes-Rodríguez et al [46] for rotation age P. radiata, although there were some differences in the definition of residue biomass, and in the age and stand conditions among the studies.…”

“…In a 35-year-old stand in NSW, Australia, the dry weight of the crown section above the top log ranged from 7% to 33% with an average of 21% of the total aboveground tree dry weight [45]. In south-central Chile, the potential harvest residue biomass of individual trees amounted to an average of 29.2 ± 7.8% of their total aboveground biomass [46]. These results are dependent on the minimum merchantable small end diameter that is specified locally and on whether stem bark is taken as a part of harvest residue, as logs are often not debarked on the logging site, but in the sawmills.…”

Using Tree Height, Crown Area and Stand-Level Parameters to Estimate Tree Diameter, Volume, and Biomass of Pinus radiata, Eucalyptus globulus and Eucalyptus nitens

“…The reported functions have many important economic and ecological applications, especially when combined with remote sensing techniques capable of estimating tree height and projected crown area. Potential uses include estimating timber appraisal and the carbon stock of forest ecosystems, determining feedstocks for bioenergy production [39][40][41], evaluating fire hazard [42,43], and assessing the risk of soil erosion [40].…”