Venceslas Goudiaby, Suzanne Brais, Yvon Grenier, Frank Berninger. (2011). Thinning effects on jack pine and black spruce photosynthesis in eastern boreal forests of Canada. Silva Fennica vol. 45 no. 4 article id 95. https://doi.org/10.14214/sf.95

Keywords: nitrogen; light; Picea mariana; Pinus banksiana; photosynthesis; thinning

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A decrease in the average diameter of commercially harvested tree species in the Eastern boreal forest of Canada has led to a decrease in availability of quality wood for the forest industry. Commercial thinning has been proposed as a means to increase stem diameter growth. However, little is known about physiological responses underlying species responses to thinning. We assessed the effect of canopy opening on the photosynthetic response of mature jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP) trees. Two years after thinning and for each species, light response curves and the diurnal course of photosynthesis were characterized from measurements taken in a completely randomized block experiment on current-year and one-year-old needles of 12 trees from stands subjected to different levels of canopy opening. Soil water content, air and soil temperatures, and needle N concentration were not affected by thinning for either species. However, light availability increased with basal area removed and could explain the significantly positive relationship between thinning intensity and diurnal course of photosynthesis for one-year-old needles of jack pine. Black spruce photosynthesis did not respond to increases in light. Light-saturated rate of net photosynthesis (A_max), photosynthetic efficiency (α), light compensation point (LCP), and diurnal respiration (R_d) did not vary with thinning for either of the species. Jack pine and black spruce responses to thinning should be interpreted in light of species autecology.

Goudiaby, NSERC/UQAT/UQÀM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, Québec, Canada E-mail: venceslas.goudiaby@uqat.ca
Brais, NSERC/UQAT/UQÀM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, Québec, Canada E-mail: sb@nn.ca
Grenier, NSERC/UQAT/UQÀM Industrial Chair in Sustainable Forest Management, Université du Québec en Abitibi-Témiscamingue, Québec, Canada E-mail: yg@nn.ca
Berninger, University of Helsinki, Faculty of Agriculture and Forestry, Department of Forest Sciences, Finland E-mail: fb@nn.fi

article id 330, category Research article

Benoit Lapointe, Robert Bradley, William Parsons, Suzanne Brais. (2006). Nutrient and light availability to white spruce seedlings in partial and clearcut harvested aspen stands. Silva Fennica vol. 40 no. 3 article id 330. https://doi.org/10.14214/sf.330

Keywords: foliar nutrients; DIFN light; Picea glauca; soil mineral nitrogen; vector analysis

Abstract | View details | Full text in PDF | Author Info

Lapointe, Université de Sherbrooke, Département de biologie, 2500 boulevard de l’Université, Sherbrooke, QC, Canada J1K 2R1 E-mail: bl@nn.ca
Bradley, Université de Sherbrooke, Département de biologie, 2500 boulevard de l’Université, Sherbrooke, QC, Canada J1K 2R1 E-mail: robert.bradley@usherbrooke.ca
Parsons, Université de Sherbrooke, Département de biologie, 2500 boulevard de l’Université, Sherbrooke, QC, Canada J1K 2R1 E-mail: wp@nn.ca
Brais, UQAT, 445 boulevard Université, Rouyn-Noranda, QC, Canada J9X 5E4 E-mail: sb@nn.ca

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