The effects of plantation spacing on Pinus resinosa wood density variation and managing for increased carbon sequestration

Abstract

Pinus resinosa is found throughout a large portion of eastern North America. Dating back to the early settlement era, wood utilization has varied from solely infrastructure to bioenergy and carbon sequestration. Although today’s Pinus resinosa wood volume has increased, research shows that wood quality has decreased and the potential for increased carbon sequestration has gone largely unnoticed. This can be explained by the current silvicultural management of Pinus resinosa which encourages quick growth and shorter harvest rotations. Wood density is not only important for loadbearing, infrastructural purposes, but a higher density in wood is the basis for increased carbon storage. The methodology for this thesis involved extracting ten individual wood core samples: five from open-grown conditions in Pembroke, Ontario and five from tightly-spaced conditions in L’Isle-aux-Allumettes, Quebec; however, the trees at each site originated from the same seed source prior to being planted. Each core was separated into juvenile and mature wood sections and were then weighed in green and dry conditions. They were tested for wood density and with the use of the Thermogravimetric Analyzer, the carbon content for each juvenile and mature sample was recovered. It was found that although each tree was genetically alike, the stand spacing at each location resulted in the respective trees having significantly different wood densities. The results showed that the trees with increased wood densities also had a higher percent carbon sequestered. These results show the importance of strategically managing the plantation spacing of Pinus resinosa and how something as simple as increasing the stand density will increase both wood density and carbon sequestration levels, while improving the structural integrity of the wood at both the stem and stand scale. These findings could be used further by forest professionals to assist in reaching Canada’s Greenhouse Gas emission targets, and producing higher-value wood products to meet market demand.