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Short-term effects of cleaning-respacing in a silver fir-dominated stand in Romania

Nicolescu, Valeriu-Norocel, Hernea, Cornelia, Șimon, Diana-Cristina, Ciolan, Matei-Nicolae, Barti, Monica-Elena, Schubert, Hendrik, Borbely, Edina
Journal of forestry research 2018 v.29 no.6 pp. 1591-1599
Abies alba, basal area, branches, dieback, growers, shoots, silver, silviculture, softwood, trees, vigor, wood quality, Romania
This paper discusses the early silviculture of silver fir (Abies alba Mill.), a major softwood in Romania covering more than 294,000 ha. Three research plots (DRP1, DRP2 and DRP3) were established in a 25-year-old silver fir-dominated stand in May 2012. In DRP1 and DRP2, heavy cleaning-respacing were carried out while DRP3 was kept as a control. After the treatments in 2012, the plots had stocking between 1470 trees ha⁻¹ (DRP2) and 10,030 trees ha⁻¹ (DRP3), basal areas between 11.8 m² ha⁻¹ (DRP2) and 31.6 m² ha⁻¹ (DRP3). The average diameters were between 5.7 cm (DRP3) and 9.6 cm (DRP2). Measurements in September 2016 confirmed the rapid response of silver fir to cleaning-respacing. The best results in average diameter increments and basal area between 2012 and 2016 were in DRP2: 3.7 cm (36.4%) and 7.7 m² ha⁻¹ (85.0%) respectively. The largest diameter trees in 2012 were the best growers, and a strong linear correlation between the initial diameter of the remaining trees and their increment was established. Natural dieback of trees occurred only in DRP3 (8.6%). The selection of crop trees based on the vigour, quality, and spacing criteria during cleaning-respacing was possible as individuals stood out in terms of vigour and early diameter growth. An issue encountered in DRP1 and DRP2 was the occurrence of epicormic shoots, especially on less vigorous individuals with small crowns. However, four years after cleaning-respacing, these branches are small and do not significantly affect the wood quality.