Regional factors drive these losses, with drought stress dominating in northern Sweden, particularly for pine planted in inverted turf on dry or fresh ground. In southern Sweden, the pine weevil creates the biggest losses. Small container seedlings are especially vulnerable to drought when planted in inverted turf in Norrland and Svealand.
Despite this, 17–27 percent of seedlings are planted in disturbed humus or unprepared spots, which is associated with lower survival across all regions. ' Effective planting methods can mitigate risks, as mineral soil spots—high pit, low pit, and hinge—give superior results for pine in all regions. ' However, climate change poses additional threats, with researchers at Stockholm University and the Swedish University of Agricultural Sciences warning that more spruce trees risk growing where they don't fit in a changed climate.
It is during the establishment phase that a large part of the future for the new forests is determined, and we clearly see that many seedlings lose out right from the start.
Large parts of spruce stands in Götaland, and also parts of Svealand, will be in poor spruce areas by the end of the century. Specific measures to reduce seedling mortality and the economic impact on the forestry industry remain unclear, as does how climate change will specifically affect survival rates of different tree species across regions.
In southern Sweden, planting where the ground is not site-prepared is a direct risk factor – here the pine weevil is unforgiving.