Département des sciences fondamentales, Université du Québec à Chicoutimi, 555 boulevard de l'Université, Chicoutimi (Québec) G7H 2B1, Canada.
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, 723 Xingke Road, Tianhe District, Guangzhou 510650, China.
Tree Physiol. 2017 Nov 1;37(11):1554-1563. doi: 10.1093/treephys/tpx082.
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.
通过疏伐减少竞争会增加许多针叶树种茎和根的径向生长。然而，人们对疏伐对木材形成动态和年轮年内发育的影响知之甚少，特别是在根中，根是树木稳定和资源获取的重要组成部分。本研究旨在评估实验性疏伐对黑云杉和香脂冷杉茎和根木质部形成动态和物候的影响。在两个成熟的同龄林分中选择了实验树和对照树，一个是黑云杉（Picea mariana (Mill.) BSP），另一个是香脂冷杉（Abies balsamea (L.) Mill.）。在 4 年的时间里，每周从 5 月到 10 月在茎和根中采集木微芯。计算了每个细胞分化阶段的开始和结束时间，以及生长速度和总细胞产量。结果表明，疏伐增加了黑云杉和香脂冷杉茎和根的细胞生产速率。这种更高的日生长速率导致形成层产生的细胞总数增加。处理的强度足以显著增加剩余树木的光照可用性，但不足以改变土壤温度和含水量，从而导致木质部形成的时间或持续时间发生显著变化。因此，疏伐增加了茎和根中细胞的生产速率和产生的细胞总数，但没有导致木质部形成物候的变化，从而不会增加春季或秋季遭受霜害的风险。
