Appraisal of Carbon Sequestration Capacity of Soil and Underground Biomass in Mixed stands of Beech and Hornbeam (A case study: Lirasar Forest- Tonekabon)

Forest ecosystems are one of the principal sources of carbon storage. The Lirehsar forest in Tonekabon was studied to assess the carbon sequestration capacity of underground biomass, soil, and roots of beech and hornbeam mixed stands. Thirty samples of uprooted beech and hornbeam trees were unintentionally selected. Soil sampling was carried out at three depths (0-10, 10-30, 30-50 cm), and root diameter sampling was conducted in six classes (50 mm) from distinct parts of the root. Soil samples were passed through a 2 mm sieve, and root samples were dried and pulverized with a grinder. The carbon storage value in beech and hornbeam roots was 8404 kg.ha-1 and 6235 kg.ha-1, respectively. The total amount of carbon deposited in soil mineral layers from 0-10 cm to 30-50 cm depth on beech and hornbeam was calculated 121 and 161 t.ha, respectively. Furthermore, the study results on soil carbon sequestration in beech and hornbeam revealed that the amount of soil carbon sequestration in all layers was 56.9, 72.5, and 62.3 t.ha for hornbeam, while its value for beech in all layers was 42, 43.6, and 35.7 t.ha. The independent t-test results showed no significant difference between carbon stored in diverse root diameters in beech and hornbeam. Findings showed that the amount of soil carbon sequestration on hornbeam was higher than on beech in all layers, revealing the influence of species diversity on soil carbon sequestration. It is expected that a variety of different tree species can be employed for reforestation in suitable areas as a result of the species diversity effect on carbon storage and carbon sequestration compared to pure beech species. It is supposed that hornbeam is a mitigated species for decomposition of soil elements and carbon sequestration in forest soil due to the developed distribution of the studied species in Hyrcanian forests.