Value of merchantable timber in Scots pine stands of different densities

Differences in the intensity of silvicultural treatments, as well as natural tree mort-ality, insect damage and fungal disease can eventually lead to variable stand density even on sites of the same quality. In addition, the bigger the initial stand density,the smaller the crown and trunk volume of single trees. The objective of theresearch was a detailed analysis of the impact of stand density on the total stand volume and value of merchantable timber. The area studied was in Drawno ForestDistrict, north-west Poland, on sites with sandy soil conditions typical for Scots pine (Pinus sylvestris L.). The total volume of merchantable roundwood wasmeasured on 20 sample plots (each covering an area of 0.5 ha) of which 19 were in 82-year-old stands and one in an 87-year-old stand. The stands were divided into three stand density groups (SDG), where the average number of trees growing per group was as follows: 547 (SDG I), 651 (SDG II) and 765 (SDG III). The volume ofa single tree was calculated using diameter (DBH) and height measurement. A qualityclassification of all 6432 tree stems was carried out in accordance with the Polish Standard. Statistical analysis did not indicate that density influenced the total timber volume of the stands studied, which was recorded as an average of 323 m3∙ha-1. However,statistically significant differences in the value of merchantable timber were observed:the highest value of 100 m3 of merchantable timber was recorded in SDG I (€ 5118.87), 6 and 12% higher than in SDGs II and III (€ 4842.09 and € 4565.80, respectively).The results obtained suggest that in the final phase (the last two age classes), pine stands growing in Polish conditions should be maintained at a lower stand density.