Artificial regeneration of an ericacees black spruce stand - Effects of scarification, fertilization and plant type 10 years later

Site invasion by ericaceous shrubs after perturbation, either natural or human, is a major concern on some sites of the boreal forest of Quebec. A dense cover of ericaceous shrubs often induces a conifer growth check, which can last several decades. An interaction study was initiated in 1991 with the general objective of developing silvicultural strategies to ensure plantation success on such sites. Black spruce, jack pine, and tamarack seedlings were planted. Stock type, scarification, and fertilization treatments were organised in a randomized block split plot design. We measured seedling total height periodically over a ten-year period and assessed basal area and survival ten years after plantation. Most responses to treatments were additive. Results indicated that mechanical soil scarification is of major importance to ensure seedling growth, both in height and basal area, on spruce-ericaceous shrub sites of northeastern Quebec. Scarification allowed a better expression of the site index, implying a sustainable impact on microsite characteristics that is greater than short-term effects on mineralization and nutrient availability. Fertilization positively influenced seedling growth, but less than soil scarification. Species choice had a strong impact on site productivity. Over a ten-year period, stock types only had a minor influence on plantation success, when compared to scarification or fertilization effects.