Soil carbon stocks and nutrient stratification differ across age-related development stages of oriental beech forests in northwestern Türkiye

Abstract

Studies on stand development and nutrient dynamics in temperate forests have reported inconsistent patterns, indicating that underlying mechanisms remain incompletely understood. This study examined soil and forest floor properties across four stand development stages (young, middle-aged, mature, and overmature) in Oriental beech (Fagus orientalis Lipsky) forests in Northwestern T & uuml;rkiye, integrating forest floor chemistry with soil carbon and nutrient stocks across the full 0-100 cm soil profile. A total of 32 plots (eight per stage) were established, and soil samples were collected from four depth intervals (0-10, 10-30, 30-60, and 60-100 cm). Soil analyses covered bulk density, fine earth content (<2 mm), texture, pH, electrical conductivity, carbonate, organic carbon, and nutrients. Forest floor samples were analyzed for mass and nutrients. Differences among stand development stages were tested using ANOVA and Duncan's test. Stand development affected soil attributes, with young stands having lower bulk density but higher concentrations of C, N, S, Fe, Cu, and Zn. Variations across soil depths were significant for all properties except P and Cu. Organic C and N stocks were highest in young stands (127 and 12 t ha(-1)). Forest floor N declined (15.2 -> 12.2 mg g(-1)) and the C/N ratio increased (29 -> 36) with stand development. Fe and Cu also varied significantly, with their stocks ranging from 41.5 to 67.5 kg ha(-1) and 0.28-0.55 kg ha(-1), respectively. Overall, young stands exhibited more favorable soil and forest floor nutrient conditions than older stands. These results demonstrate that stand development strongly regulates below- and aboveground organic matter and nutrient dynamics, providing a basis for ecological assessment, silvicultural planning, and sustainable management of Oriental beech forests.