Using Macronutrient Distributions within Trees to Define a Branch Diameter Threshold for Biomass Harvest in Sugar Maple-Dominated Stands

Abstract

Abstract:As the use of forest harvesting residues for energy production gains popularity, debate continues regarding the long-term sustainability of whole tree harvesting (WTH). This practice removes nutrient-rich twigs that only account for a small fraction of harvest residues, emphasising the need to develop nutrient-efficient alternatives to WTH. This study assessed N, P, K, Ca, and Mg distributions within sugar maple (Acer saccharum Marshall) and yellow birch (Betula alleghaniensis Britton) branches of various sizes in order to determine the branch diameter threshold that would represent the best compromise between the quantity of harvested biomass and nutrient losses that were generated. Quantities of nutrients that were exported with harvesting were then modelled at the stand level using different biomass harvest scenarios to explore what factors ultimately drove total quantities of nutrients exported with harvest. We found that the branch diameter threshold for biomass harvesting should be set at 2 cm for most nutrients in both tree species. An exception was Mg in yellow birch, for which the harvesting of branches larger than 10 cm would always generate larger nutrient export than gains in terms of biomass. At the stand scale, we provide evidence that the intensity of biomass harvest (i.e., the number of branch compartments harvested) is the principal factor responsible for the quantity of nutrient that is exported with harvesting.

Fiber morphology in walnut branchwood: Relation to the branch diameter, branching level, and tension wood

“…Compared to thick branches, thin branches had smaller fibers, which may be due to the effects of the cambial age and the control of the meristem at the top of the branches (Nicolini et al 2001;Peterson et al 2007). The branch diameter is an important tree variable in plantation management because it has considerable influence on the tree growth, timber quality, fruit yield, and important physiological processes (Dong et al 2016;Royer-Tardif et al 2017;Jin et al 2019). Although significant correlations exist between the fiber morphometrics and the diameters of the branches at pvalue less than 0.05 or p-value less than 0.01 levels, the branch diameter may not be adequate to forecast fiber morphometrics, due to the absolute value of Pearson's correlation coefficients (r is less than 0.13).…”