Development of Norway spruce dominated stands after single-tree selection and low thinning

• Published in: Canadian Journal of Forest Research
• Main Authors: Lähde, Erkki, Laiho, Olavi, Norokorpi, Yrjö, Saksa, Timo
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2002
• Subjects: Ecology; Forestry; Global and Planetary Change; Norway; Northern Finland
• Online Access: http://dx.doi.org/10.1139/x02-075; http://www.nrcresearchpress.com/doi/pdf/10.1139/x02-075

The study included 23 stands (at least 2 ha each in size) distributed from southern to northern Finland. These Norway spruce (Picea abies (L.) Karst.) dominated stands grew on fertile (Oxalis–Myrtillus and Myrtillus site types) mineral soils. Each stand contained two substands randomly treated with single-tree selection or low thinning. The harvested volumes (trees > 9 cm) varied greatly but averaged 94 m 3 ·ha –1 in the former consisting of mainly medium-sized and larger (>15 cm) trees and 68 m 3 ·ha –1 in the latter of mainly medium-sized and smaller (<15 cm) trees. After treatment, mean diameter at breast height (DBH), basal area, and stand volume were 12–17% lower in single-tree selection than in low thinning. The stem distributions were reverse-J shaped and bell shaped, respectively. During the monitoring of a mean of 11 years, about one cutting cycle in single-tree selection, stand volume (trees > 9 cm) increased 38% in single-tree selection and 27% in low thinning. The respective current annual volume and relative increments were 5.4 (3.6%) and 4.6 m 3 ·ha –1 ·year –1 (2.4%). In 18 (volume) and in 22 (relative) of the 23 plot pairs the increment was higher after single-tree selection than after low thinning (p values 0.013 and <0.001, respectively). Single-tree selection plots additionally included 1300 saplings/ha (from breast height to DBH 9 cm) after cutting, with the transition of 80 saplings/ha into larger trees and with the ingrowth, mainly spruce, of 170 seedlings/ha into saplings during monitoring.