Transversal tracheid dimension in thinned black spruce and Jack pine stands in the boreal forest

Abstract

Commercial thinning has recently been applied in the boreal forest of Quebec (Canada) to increase the volume growth of the residual trees. We aimed to discover if the growth response influences the transversal tracheid dimension of thinned black spruce (Picea mariana (Mill.) B.S.P.) and Jack pine (Pinus banksiana Lamb.) stands at 0.2 m stem height. All 20 studied stands have shown a significant growth response after the treatment (p<0.0001), especially trees with the lowest radial growth before thinning in comparison with the stand mean. Growing conditions met by suppressed trees before thinning might favour them in the competition for light, water and biomass production after the treatment. Trees with a positive growth response did not significantly modify their measured transversal tracheid dimension except for trees which increased twofold their ring-width after thinning. In this case, lumen area and radial cell diameter extended significantly. However individuals with a growth decrease after thinning registered significantly lower values in their ring width, earlywood and latewood cell numbers (p<0.0001) in both species.

Keywords:

• Transversal tracheid dimension
• radial growth
• commercial thinning
• black spruce
• Jack pine
• boreal forest

Acknowledgements

Special thanks to Dr. Sergio Rossi for his helpful comments on the article as well as Denis Walsh for his advice on statistics. We would also like to thank Mireille Boulianne, Maxime Thibeault-Martel, Andres Castro Estupinan, Patrick Émond, Émilie Lapointe, Manon Vincent, Marie-Claude Duchesne and Mehrdad Matboueriahi who helped during the fieldwork.