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Physiological responses of black spruce layers and planted seedlings to nutrient addition

Summary

Published in Tree Physiology 20: 229-238

We investigated effects of nutrient addition on several physiological characteristics of 60-cm-tall black spruce (Picea mariana Mill. B.S.P.) layers (i.e., rooted branches of overstory trees) and 20-cm-tall planted seedlings on a clear-cut, N-limited boreal site. After two growing seasons, current-year and one-year-old needles of fertilized trees (layers and seedlings combined) had higher net photosynthetic rates (An) and maximum capacity of Rubisco for CO2 fixation (Vmax) than unfertilized trees. One-year-old needles of fertilized trees had higher stomatal conductance (gs), higher water-use efficiency, and lower intercellular to ambient CO2 ratio than unfertilized trees. Additionally, fertilized trees had higher predawn and midday shoot water potentials than unfertilized trees.

Stomatal conductance of 1-year-old needles was 23% higher in seedlings than in layers, but there were no significant differences in gs of current-year needles between the regeneration types. For both needle age-classes, An and Vmax of layers were 25 and 40% higher, respectively, than the corresponding values for seedlings. The higher values of An, Vmax and foliar N concentration of layers compared with seedlings after two growing seasons may be associated with the larger root systems of the layers compared with the transplanted seedlings.

Sector(s): 

Forests

Categorie(s): 

Scientific Article

Theme(s): 

Forestry Research, Forests, Silviculture

Author(s)

PAQUIN, Raynald, Hank A. MARGOLIS, René DOUCET and Marie R. COYEA

Year of publication :

2000

Keywords :

silvicultural regime, fertilization, photosynthesis, conifer, Picea mariana, black spruce, Rubisco capacity, stomatal conductance, water stress, water-use efficiency, Chibougamau, shoot water potential, gas exchange, chemical analysis, statistical analysis, foliar analysis, sylviculture des forêts naturelles résineuses, sylviculture des forêts naturelles, silviculture and yield of natural forests - softwood stands

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