The effect of planting stock and soil scarification on forest regeneration

Abstract The present research is a comparative analysis of how the main quality indices of containerized and barerooted coniferous (Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.)) planting stock conform to the existing standards in Estonia, how the plantation development depends on planting stock and natural regeneration on soil scarification. The height of Scots pine containerized seedlings exceeded that of barerooted seedlings by 20%. The height of barerooted Norway spruce transplants exceeded that of containerized seedlings by 19%. The root-collar diameter of containerized pine stock formed 70% and the corresponding index of containerized spruce stock formed 48% of the diameter of the barerooted plants of the same species. Typically, containerized plants had better initial growth increment during the first two to three years after planting but this difference disappeared during the latter years. The growth of Scots pine barerooted and containerized seedlings was similar, while the growth of Norway spruce containerized seedlings was slightly inferior compared to barerooted plants. Survival of both test species was independent of planting stock used. After clear-cutting, certain areas of peatland and mineral areas were disc-trenched and inventoried at the end of the first growing season. The number of all woody plants was determined by microsites – untreated area, furrow, slope, and ridge. The same inventory was repeated 11 growing seasons later. After 11 growth years, a large number of Scots pine trees was found in Rhodococcum, Oxalis and Vaccinium myrtillus site types and drained peatlands. The number of pine plants on microsites on mineral soil was the greatest in furrows and on slopes (34% and 30%), and on peat soil on furrows and in untreated areas (47% and 53%). The number of naturally regenerated Norway spruce trees was the largest in Vaccinium myrtillus, Oxalis-Rhodococcum and Oxalis site types. With regard to microsites, spruce plants were the most abundant in furrows and ridges on mineral soil (31% and 24%) and in untreated areas and on slopes on peat soil (46% and 42%).