Jäärats, A., Sims, A. and Seemen, H. 2012. The Effect of Soil Scarification on Natural Regeneration in Forest Microsites in Estonia. Baltic Forestry 18(1): 133-143.

Soil scarification is one of the main methods for enhancing natural regeneration and it is widely used before seeding and planting as well. The aim of this research was to assess the effect of soil scarification on natural regeneration in the 11-year-old forest regeneration areas in fertile mineral soil and peatland sites. After clear-cutting, these areas were disc-trenched with Donaren 190 and inventoried after the first growing season. The inventory was performed using rectangular sample plots ranging in size from 10x10 to 15x20 m. The number of all woody plants was determined by microsites – untreated area, furrow, slope, and ridge. The same inventory was redone 11 growing seasons later.

After 11 growth years, a large number of Scots pine trees (Pinus sylvestris L.) was found in Vaccinium myrtillus, Vaccinium vitis-idaea, and Oxalis site types and drained peatlands, with 2,600–5,300 trees per hectare. The number of pine plants on microsites on mineral soil was the greatest in furrows and on slopes (33.5% and 30.4%), and on peat soil on slopes and in untreated areas (38.3% and 52.1%). The number of naturally regenerated Norway spruce (Picea abies (L.) Karst) trees was the largest in Oxalis-Vaccinium vitis-idaea, Vaccinium myrtillus and Oxalis site types, with 2,000–3,000 plants per hectare. With regard to microsites, spruce plants were the most abundant in untreated areas and in furrows on mineral soil (23.2% and 34.6%) and in untreated areas and on slopes on peat soil (54.3% and 37.0%). Among deciduous trees, birches (Betula pendula Roth., Betula pubecens Ehrh.) and aspens (Populus tremula L.) as well as other deciduous trees (Salix sp. L., Tilia cordata L., Alnus sp L., Sorbus aucuparia L., Prunus padus L., Fraxinus excelsior L.) were mostly growing in untreated areas on both mineral and peat soil. Soil scarification increased consistently the number of conifer seedlings in the sites typical of Norway spruce and Scots pine (p<0.05), where no effect was detected in the number of deciduous saplings.

 Key words: soil scarification, microsites, forest site types, natural regeneration