Linkages between the Structure of Annual Rings of Scots Pine and Stand Density in the Region of the Chernobyl Accident

Abstract

We have studied the features of annual ring development in stands of Bryansk oblast polluted by radionuclides from the Chernobyl accident. The evidence of relationships between average annual radial increment and the average width of spring and summer layers of timber within an annual ring and stand density is observed in 80-year-old blueberry pine forests. We find direct links between annual increment and its spring and summer components with average distance between trees. The stand density has the most pronounced effect on the spring growth of timber, with an increment gradient from 0.204 to 0.244 mm m^–1. In summer it varies from 0.038 to 0.066 mm m^–1. The contribution of the late timber in a tree ring increases from 50.4–54.8% in the least dense to 72.5–75.8% in the densest stands. However, chronic irradiation does not differ across the stand density gradient. The stimulation of the annual growth increment by irradiance is estimated from 50.4 to 51.9%. It contributes from 39.1 to 46.1% of the spring increment to 43.2–58.6% of the summer increment with 95% confidence.