Gap Size in Hyrcanian Forest Affects the Lignin and N Concentrations of the Oriental Beech (Fagus orientalis Lipsky) Fine Roots but Does Not Change Their Morphological Traits in the Medium Term

Research Highlights: Fine roots play an important role in plant growth as well carbon (C) and nutrient cycling terrestrial ecosystems. Gaining a wider knowledge of their dynamics under forest gap opening would improve our understanding soil input below-ground stock accumulation. Single-tree selection is increasingly recognized alternative regime cutting sustaining biodiversity stock, along with timber production, among ecosystem functions. However, the fine root response terms morphological chemical composition to resulting harvest-created gaps remains unclear. Background Objectives: This paper investigates effect medium term (i.e., 6 years after logging) differently sized on composition. Materials Methods: A total 15 (86.05–350.7 m2) adjacent 20 m distant closed canopies (control) were selected temperate Fagus orientalis (Hyrcanian region, Iran). Eight cores collected at cardinal points edge, including four facing area—the same intact forest. Results: For edge trees, different size gaps, core position, tree orientation did not affect investigated traits, except for slightly higher specific length (SRL) larger fraction (1–2 mm) side area. Differently, traits such N concentration cellulose:lignin ratio significantly increased increasing size, opposite C:N lignin. Moreover, decreased diameter, respectively. Conclusions: work highlighted that, within adopted range, artificial derived from single-tree practice affected chemistry rather than biomass morphology gap-facing trees. The six creation might have been long enough recovery standing pre-harvest condition, particularly near stem clear threshold come out; nevertheless, 300 m2 may be considered possible cut-off determining marked change responses roots.