Xylogenesis in stems and roots after thinning in the boreal forest of Quebec, Canada

Abstract

The reduction of competition through thinning increases radial growth in the stem and roots of many conifer species. However, not much is known about the effect of thinning on the dynamics of wood formation and intra-annual development of the growth ring, especially in the roots, which are an essential part of the tree for stability and resource acquisition. The aim of this study was to evaluate the effect of an experimental thinning on the dynamics and phenology of xylogenesis in the stem and roots of black spruce and balsam fir. Experimental and control trees were selected in two mature even-aged stands, one black spruce (Picea mariana (Mill.) BSP) and one balsam fir (Abies balsamea (L.) Mill.). Wood microcores were collected weekly in the stem and roots from May to October for a period of 4 years. The onset and ending of each cell differentiation phase were computed, as well as growth rate and total cell production. Results show that thinning increased the cell production rate of stem and roots of black spruce and balsam fir. This higher daily growth rate caused an increase in the total number of cells produced by the cambium. The intensity of the treatment was sufficient to significantly increase light availability for residual trees, but insufficient to modify soil temperature and water content to a point at which a significant change in the timing or duration of xylogenesis would be induced. Thus, thinning increased cell production rate and total number of cells produced in both stem and roots, but did not result in a change in the phenology of wood formation that could lead to increased risks of frost damage in the spring or autumn.

Primary and Secondary Branch Growth in Black Spruce and Balsam Fir after Careful Logging around Small Merchantable Stems (CLASS)

“…Besides the mechanical importance, the larger secondary growth also has a physiological importance. More resources invested in secondary growth implies that more cells are produced by the vascular cambium of the branches [5]. These additional cells can transport more water to the site of photosynthesis.…”

“…Stem growth can increase after silvicultural treatments such as CLASS or thinning [4][5][6]. Branch growth and size can also be influenced by stand conditions and modified through silviculture, with larger branches occurring generally on trees from stands that have been thinned or planted at a wider spacing [7][8][9].…”

Tree ring-based reconstruction of the long-term influence of wildfires on permafrost active layer dynamics in Central Siberia

“…However, despite the importance of roots for tree stabilization, as well as absorption and transport of water and minerals, investigations of tree roots in boreal and especially permafrost zones are relatively rare and mainly focused on root biomass estimations and above-to belowground carbon partitioning (Baret et al, 2015;Kurz et al, 1996;Mokany et al, 2006 and references therein). Most tree-ring studies of roots are devoted to specific questions, like understory competition (Zaitsev et al, 2018), effect of thinning (Krause et al, 2014;Lemay et al, 2017;Vincent et al, 2009;Ruel et al, 2003), species adaptation to local soil conditions (Kajimoto et al, 2003;Krause and Morin, 2005).…”

Maximum Branch Diameter in Black Spruce Following Partial Cutting and Clearcutting

“…In all cases, partial cutting and clearcutting reduce competition and increase the availability of light, water, and nutrients for the remaining trees; this leads to increased growth in the stem [25,26] and other parts of the tree, including roots and branches [13,27,28]. Increases in branch size due to a modified stand density (after thinning or partial cutting) can therefore result in bigger knots that could likely end in a marked downgrading of potential product recovery and quality.…”