Nutrient status of black spruce (Picea mariana [Mill.] BSP) forest soils dominated by Kalmia angustifolia L.

Sites dominated by Kalmia angustifolia L. are often associated with slow decomposition of organic matter, decreased nitrogen (N) mineralization rates, and low black spruce (Picea mariana (Mill.) BSP) productivity. The objective of this study was to separate the effects of belowground competition by Kalmia from the effects of water-soluble soil phenols on black spruce seedlings growing under different levels of Kalmia cover. A factorial greenhouse bioassay was established in which black spruce seedlings were grown for 6 months in intact blocks of soil with three different levels of Kalmia cover. The soil was treated with charcoal to reduce the amounts of water-soluble phenols, and (or) tubes were inserted to exclude Kalmia roots. At low Kalmia cover, reducing the level of belowground competition increased seedling biomass by 134%. However, reducing belowground competition did not increase seedling biomass at the two higher levels of Kalmia cover. It is possible that seedling biomass remained low because of an increased immobilization of N in the organic layer. Furthermore, the proportion of ectomycorrhiza morphotypes differed among seedlings growing under different levels of Kalmia cover. The effect of water-soluble phenols on seedling growth remains uncertain, since we observed a confounding effect of the charcoal treatment on soil microbial biomass and seedling response.

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Croissance et statut nutritif de marcottes, de semis naturels et de plants d'épinette noire à la suite du scarifiage : résultats de 10 ans

Canadian Journal of Forest Research ◽

10.1139/x03-130 ◽

2003 ◽

Vol 33 (11) ◽

pp. 2097-2107 ◽

Cited By ~ 26

Author(s):

Marcel Prévost ◽

Daniel Dumais

Keyword(s):

Boreal Forest ◽

Picea Mariana ◽

Natural Regeneration ◽

Black Spruce ◽

Nutrient Status ◽

Height Growth ◽

Site Preparation ◽

Tree Planting ◽

Initial Growth ◽

Artificial Regeneration

Careful logging around advance growth (CLAAG) and tree planting following site preparation or not (fill planting) are widely used to regenerate black spruce (Picea mariana (Mill.) BSP) stands in the boreal forest of Quebec, Canada. However, few mid-term studies have compared these different regeneration modes. In this study, we examined height growth and nutrient status of black spruce layers, natural seedlings, and planted seedlings over a 10-year period, in an experimental design combining CLAAG, natural seeding, planting, and two types of scarification (cones and disks). Without scarification, growth of planted seedlings (5.8 cm·year1) was slightly greater than that of layers (4.4 cm·year1) and natural seedlings (4.1 cm·year1). Scarification improved growth of the three types of regeneration, but the treatment was more beneficial for planted seedlings (+7.1 cm·year1) than for natural seedlings (+1.6 cm·year1) and layers (+1,0 cm·year1). Five years after treatment, scarification had increased the current-year needle N concentration of the three types of regeneration, but this beneficial effect on N was still detectable only in foliage of layers after 10 years. The effect of the treatment was variable for P and K contents, for which natural regeneration seems to have taken advantage more than plants. Our results indicate that scarification can improve the initial growth and nutrient status of both natural and artificial regeneration of black spruce and thus accelerate site recovery after cutting in the boreal forest. Furthermore, fill planting without site preparation appeared to be clearly less efficient than planting combined with scarification.

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