Exploring land cover change patterns in Hyrcanian forests through spatiotemporal trend analysis (2000–2022)

Forests play a crucial role in maintaining environmental balance by providing a wide range of valuable ecosystem services. Monitoring their change dynamics is increasingly important for planning, decision-making, and especially for evaluating conservation policies. Due to the significance of this issue, the number of studies examining global forests in terms of change trends is not uniform. The Hyrcanian forests, recognized as one of the most important temperate forests in the world and listed as a UNESCO World Heritage site since 2019, serve as a notable example. The study of their change trends, particularly in light of recent conservation policies, has gained increasing importance. This study aims to analyze the spatial-temporal change trends of the Hyrcanian forests from 2000 to 2022 using remote sensing products. To assess the intensity and direction of changes, Sen’s slope and Mann-Kendall tests were employed. The results indicate 78,609.51 ha of degradation and 85,579.15 ha of deforestation during the study period in this region. Meanwhile, the forest restoration effort has only covered 45,525.90 ha, emphasizing the imbalance between deforestation and restoration. Deforestation is primarily driven by the expansion of agricultural lands, accounting for 79.45% of the total changes. Impervious surfaces and shrublands follow with 7.66% and 5.67%, respectively. In contrast, forest restoration has mostly occurred through the conversion of agricultural land into forests, with agricultural land contributing 74.26% to this process. Grasslands and shrublands follow with 8.14% and 7.65%, respectively. The economic analysis also revealed that deforestation has led to a loss of $1.033 billion in ecosystem service value from the Hyrcanian forests. Among the major policies, the implementation of the forest rest plan in 2016 and the inclusion of the Hyrcanian forests in the UNESCO World Heritage List in 2019 have played a significant role in mitigating forest degradation. Prior to these policies, forest degradation in some years reached approximately 4000 ha, but following their implementation, it was reduced to around 1500 ha. Additionally projections for 2030, 2040, and 2046 show that, without continued protective policies, the forest area could decrease by up to 64,340 ha by 2046, while with the continuation of policies, the forest area could increase by up to 28,554 ha. These findings demonstrate the effectiveness of conservation policies and emphasize the necessity for their continuation and strengthening, along with revising land management practices, planning for ecosystem restoration, and ensuring the sustainable use of natural resources.