Restoring Soil Features and Biodiversity Indicators in Managed Forests to the Levels of Protected Forests: After One Silvicultural Rotation Period

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This study examines the provision of ecosystem services in natural mixed broadleaf forests located in the Hyrcanian region of Iran. These services include habitat conservation, soil preservation, timber production, and carbon storage (C-stock). The forests are managed under three different silvicultural methods: shelterwood, selection cutting, and protection, allowing for a comparative analysis of their impact on these critical services. The time since the last cutting operation varied among the forest stands. In the shelterwood stand, 25 years had passed since the previous operation, while in the selection cutting stand, it had been 13 years. In contrast, the protected stand had remained untouched by logging for the past 40 years. This presents a valuable opportunity to assess the effects of the recovery period and evaluate the extent of ecosystem service restoration. Additionally, it allows for determining whether these services have reached the levels observed in a protected forest. The results show that habitat conservation, soil preservation, and carbon stock (C-stock) values ranked as follows: protection > selection cutting > shelterwood. In contrast, timber production values were highest under selection cutting, followed by shelterwood, and lowest in protected areas. Furthermore, the Stand Structural Complexity Index (SCI) was greatest in protected stands, with selection cutting and shelterwood-managed stands ranking second and third, respectively. Similarly, species diversity indices, the abundance of large-diameter trees, and the volume of deadwood followed this same trend. These findings highlight a trade-off in forest management practices. While selection cutting and shelterwood management simplify stand structure to enhance timber production and maximize economic returns, they also lead to a significant reduction in other critical forest ecosystem services. Our findings further revealed that, even decades after the cessation of forest operations, the ecological value of previously managed forests remains substantially lower than that of protected forests. Moreover, the results demonstrate that a single silvicultural rotation period is insufficient to fully restore the ecological value of managed forests, regardless of whether they were subjected to selection cutting or shelterwood management practices.