Summary
Published in Forest Ecology and Management 260: 219-228
Vegetative layering of black spruce (Picea mariana [Mill.] B.S.P.) is the principal mode of regeneration for over mature, uneven-aged stands subject to long fire cycles (>300 years) in northeastern Québec, Canada. However, growth response of black spruce layers following disturbance by fire or harvest can be slow, due to a lag of morphological acclimation and potential nutrient limitation. This phenomenon can be accentuated if black spruce is associated with ericaceous shrubs such as Kalmia angustifolia and Rhododendron groenlandicum, which are known to interfere with conifer growth through direct and indirect competition. Such interactions can result in productive stands being converted to unproductive heathlands. It is not known whether these effects of ericaceous shrubs on black spruce are accentuated on low fertility sites, or if the impacts are independent of inherent site fertility. The objectives of this study were to evaluate the effects of ericaceous shrubs on both resource availability and on functional traits of black spruce advance regeneration across a gradient of site fertility (as defined by a site classification system). We monitored black spruce advanced regeneration physiology and soil nutrient availability over two growing seasons on a gradient of ecological site types in northeastern Québec (Canada). The eradication of competing vegetation favored higher soil NH4-N and K availability, with increases of 67% and 28% compared to control conditions, respectively. Black spruce photosynthesis rate (A) and foliar K content were higher in plots where vegetation was eradicated, compared to the control plots, but did not vary among ecological site types. Photosynthesis did not appear to be limited by nitrogen or water relations, but was possibly limited by a deficit of foliar K+, probably resulting from reduced availability following sequestration by the ericaceous root systems. The absence of interaction between inherent site fertility and the eradication of ericaceous shrubs suggests that vegetation management of ericaceous shrubs must be planned independently from the ecological site type.
Sector(s):
Forests
Categorie(s):
Scientific Article
Theme(s):
Forestry Research, Forests, Silviculture
Departmental author(s):
Author(s)
HÉBERT, François, Nelson THIFFAULT, Jean-Claude RUEL and Alison D. MUNSON
Year of publication :
2010
How to get the publication :
Keywords :
éricacées, épinette noire, photosynthèse, fertilité, compétition, coupe forestière, sylviculture des forêts naturelles résineuses, picea mariana, sylviculture et rendement des forêts naturelles - peuplements résineux, black spruce, ericaceous shrub, photosynthesis, site fertility, competition, logging, silviculture and yield of natural forests - softwood stands
