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Since 1950, the creation of open woodlands has increased in Canada's northeastern continuous boreal forest and recent studies have demonstrated that the mechanisms underlying their creation are similar to those found in the lichen woodland zone. Since no natural re-densification of open woodlands has been observed to date, afforestation is necessary to counteract an increase of these types of stands in the continuous boreal forest. The aim of this study was to test the operational feasibility and success of afforestation efforts in open woodlands, 10 years after planting. The experimental design included different containerized seedling stocks and site preparation approaches, such as patch and disk scarification, and covered most of the geographical range of accessible continuous boreal forest in Quebec. In open woodlands, regardless of black spruce stock size, disk scarification increased planted seedling survival and growth compared with patch scarification and direct planting, possibly due to a beneficial effect on seedling nutrition. However, even if seedling growth in open woodlands and feathermoss stands submitted to disk scarification was comparable, growth was higher in the latter stands. Nonetheless, we conclude that disk scarification followed by planting is an appropriate method to afforest boreal open woodlands.

Black spruce-lichen woodlands (LW) are naturally occurring unproductive low tree density stands within the eastern North American closed-crown boreal forest. Natural reforestation in LWs is impeded by the lichen mat and ericaceous shrubs that inhibit seedling establishment. Disk scarification is a mechanical site preparation method that creates furrows where lichens and shrubs are removed and mineral soil is exposed, which is the preferred seedbed for black spruce natural regeneration. The objective of this study was to quantify the impact of disk scarification on black spruce establishment in LWs by natural seeding. Disk scarification was performed amid scattered seed trees in six study sites located in the central area of boreal Quebec's spruce-moss bioclimatic domain. Newly established black spruce seedlings were significantly more abundant (ca. 81%; χ2 = 28.72, P < 0.001) in the furrows of scarified plots even though the proportion of disturbed soil was small (ca. 20%). Seedling establishment occurred for at least 3 years following scarification, with a peak in the first year. The distribution and density of seed trees (112‐363 stems ha−1) did not limit natural seedling establishment in this study. Five years after scarification, observed densities and stocking levels of newly established black spruce seedlings were sufficient to expect afforestation without planting in scarified LWs.

We investigated the effects of foliar absorption of dew by eastern white pine (Pinus strobus L.) seedlings on midday shoot water potential, as well as on other water relations variables and growth. Two-year-old container-grown eastern white pine seedlings were subjected to contrasting watering regimes (normal and deficient) and three frequencies of artificial dew (none, once and three times per week) for 10 weeks in a greenhouse. Midday shoot water potential was measured on four occasions during the study. Other water relations variables (relative water content, stomatal conductance, pressure-volume curves) and growth (hypocotyl diameter, aboveground dry mass, root dry mass) were also measured. Artificial dew significantly increased shoot water potential, stomatal conductance and seedling root growth, with greater responses observed for seedlings subjected to a deficient watering regime than for well-watered seedlings. Because dew can be a frequent microclimatic event in some areas, this finding has practical implications for field studies of water relations of eastern white pine and possibly of other coniferous species.