Assessing soil organic carbon, N and P stocks and its relation to soil properties in artificial canopy gaps in a managed oriental beech (Fagus orientalis L.) forest

Background In the Hyrcanian temperate forests, different canopy gaps sizes have been created by logging under silvicultural methods. Understanding the effects of gaps on forest ecosystems can help in the planning and decision-making of forestry practices. Variations in ecological conditions caused by canopy gaps may have an impact on the forest stand, particularly soil nutrients. Aims The purpose of the present research was to investigate the changes in soil organic carbon (SOC), total nitrogen (N) and phosphorus (P) stocks under different gap sizes in the Hyrcanian oriental beech forest. Methods We measured SOC, N and P stocks of soil at the depth of 0-20 cm among 15 artificial gaps along with adjacent closed stand which was created by single-tree selection system in oriental beech stand, northern Iran. In the center and four cardinal positions of the edge of gaps as well as in the four adjacent closed canopy forests at the distance of 20 m from gaps, the soil sampling was performed. Results The difference in C, N and P stocks among the artificial canopy gaps was statistically significant, and higher mean values were observed in large gaps. No significant difference was observed between gaps and adjacent closed stands with regard to soil C, N and P stocks. At artificial gaps and closed stands, the SOC stock was negatively correlated with clay and positively correlated with bulk density, sand, N and OC. With increasing bulk density, sand, N, P, and OC, N stock was increased in gaps. In gaps, SOC and P stocks were both positively related to soil microbial C and soil microbial P, respectively. Conclusion Generally, it can be stated that there are similar relative ecological conditions between artificial gaps and closed stands, and the interaction among soil properties in gaps demonstrates gap dynamics in deciduous, broad-leaved beech forest.