Fractional composition of phytomass and annual production of Scots pine (Pinus sylvestris) under the conditions of the dry steppe zone of chestnut soils

Increasing phytomass stocks in steppe zones can be achieved through agroforestry reclamation measures, specifically by establishing artificial protective forest plantations (PFPs). Artificially created protective forest plantations perform important functions in dry-steppe regions, including soil protection, environmental regulation, water conservation, and sanitary-hygienic roles. Scots pine (Pinus sylvestris L.) is widely used for sand stabilization, preventing desertification, and restoring degraded lands. In addition, it is an effective carbon sink, sequestering up to 2.4 t of CO₂ per year, thereby enhancing ecosystem resilience to climate change. The aim of this study was to assess the phytomass stocks and annual production of artificially established Pinus sylvestris plantations in the dry-steppe zone of chestnut soils, taking into account the age dynamics of the stand. The primary calculation method was allometric modelling based on forest inventory data obtained from a complete enumeration survey conducted on 10 sample plots. Phytomass stocks were calculated for the following fractions: stem with bark (Pst), branch skeleton (Pbr), needles (Pf), and roots (Pr). The results showed that phytomass stocks ranged from 29.2 t/ha in young stands of age group I to 120.3 t/ha in mature stands. The dominant fraction in the phytomass structure is the stem with bark (Pst), accounting for 51.7–59.6% of the total. Annual production strongly depends on tree age. A gradual increase from young to mature stands was observed, reaching maximum values at an optimal balance between growth and physiological stability in middle-aged stands (3 t/ha/year), while the minimum values were recorded in age group I young stands (1.26 t/ha/year). The obtained data on phytomass stocks in artificial pine plantations can be used for planning agroforestry reclamation measures and assessing their contribution to greenhouse gas sequestration in the development of climate adaptation projects.