Maximum Branch Diameter in Black Spruce Following Partial Cutting and Clearcutting

Audrey Lemay,Cornelia Krause,Émilie Pamerleau-Couture

doi:10.3390/f10100913

Abstract

Branch diameter is an important aspect of wood quality, as lumber grades can be determined based on the maximum diameter of branches. Crown and branch development can be influenced by the environment surrounding the trees, and silvicultural interventions, which reduce stand density and increase the growth of residual trees, could therefore alter branch properties. We evaluated maximum branch diameter within the crown of residual black spruce (Picea mariana (Mill.) B.S.P.) subjected to five types of silvicultural intervention—three partial-cutting and two clearcutting treatments—as well as trees within unmanaged control stands. We sampled a total of 41 stands and 223 trees. We collected 15 whorls from the live crown of each tree and measured the diameters of the largest branches. For all treatments, we observed a curvilinear relationship between maximum branch diameter and distance from the stem apex, and the largest branches were located in the lower third of the live crown. DBH before treatment and treatment were the variables that best explained maximum branch diameter in the lowest portion of the crown. A generalized additive model showed that maximum branch diameter in black spruce following silvicultural treatment will not differ significantly from trees of unmanaged control stands. Therefore, the studied partial cutting and clearcutting treatments do not have adverse effects on maximum branch diameter when compared to unmanaged control stands. However, DBH prior to treatment must be considered before any treatment is applied in forest management operations if maximum branch diameter is an important wood quality factor at the time of the final harvest of the stands.

Highlights

Black spruce (Picea mariana (Mill.) B.S.P.) is a dominant species in the boreal forest of eastern NorthAmerica
Wood quality can be defined as the wood characteristics and properties that make the wood valuable for a given end use [3,4]; wood quality represents a multi-faceted assessment that depends on the intended use the wood
Our study showed that the measured maximum branch diameter in black spruce varied depending on the harvesting treatment

Summary

Introduction

Black spruce (Picea mariana (Mill.) B.S.P.) is a dominant species in the boreal forest of eastern NorthAmerica. It is valuable to the forest industry for timber production and pulp and paper due to the excellent quality of its fiber [1,2]. Wood quality can be defined as the wood characteristics and properties that make the wood valuable for a given end use [3,4]; wood quality represents a multi-faceted assessment that depends on the intended use the wood. Stem diameter and form, wood density, strength and stiffness, juvenile wood content, tracheid length, microfibril angle, and compression wood are some of the most important attributes for defining wood quality in general [3,5]. Other attributes associated with the live crown are highly important for the study of wood quality; these properties include the number and size of branches and knots in the finished products. In particular large-diameter branches, create a zone of weakness

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