Impact of Thinning Levels on Cone Production in Natural Stands of Scots Pine (Pinus sylvestris L.)

Abstract

Scots pine (Pinus sylvestris L.) grows from sea level up to 2700 m as small groups or individually in Türkiye. Cone and seed production is the main tool in sustainability of forest tree species. However, many biotic and abiotic factors such as stand structure and forestry practices could impact production. The impact of thinning levels (unthinned or known control, moderately thinned, and heavily thinned in 2021) together with growth characteristics on mature cone production was examined based on two-year cone data (2024 and 2025) in natural stands. Stands and individuals within stands were evaluated for both cone production and growth. Heavily thinned stands had higher cone production for both years (16.8 and 96.6) than moderately thinned (9.7 and 40.7) and unthinned (9.5 and 32.6). The year 2025 produced more abundant cones (55.4) than 2024 (11.9). Significant (p < 0.05) differences were found with respect to thinning level for growth characteristics and cone productions except for tree and crown heights. Years showed significant (p < 0.05) differences among grades and within grade for cone productions. Additionally, growth characteristics had generally significant (p < 0.05) impact on cone production in both grade and years.