Habitat trees in mixed stands and mid-altitude elevation in Hyrcanian forests (Case study: Kheyrud forest, Nowshahr)

Background and objectives: Certain structural elements of forests, such as habitat trees, serve as crucial habitats and environmental modifiers for a multitude of organisms. This leads to an enhancement in the structural richness and resilience of ecosystems. The focus on habitat trees and biodiversity conservation in forests entails the management of specific elements inherent in the forest’s natural evolutionary cycle. Consequently, this study aimed to examine the structural characteristics of habitat trees in mixed and transition forests within some managed stands in the Kheyrud forest, Nowshahr County.
Methodology: Stands 305, 306, 309, 310, and 311 in Gorazbon were chosen for the study. Gorazbon is a part of the mixed broadleaf forests of the Caspian region, situated within the Khairud educational and research Forest of Tehran University. It is located seven kilometers east of Nowshahr city in the Hyrcanian forest belt of Iran. For this research, all trees exhibiting specific characteristics were measured for their diameter with 100% accuracy across all the mentioned parcels. The conditions sought included broken trees, fungi, hollow from the stump, uprooted, broken stems, deformed, curved, tuberous, with nests, dead trees, old trees, and with witch’s broom. A variety of criteria and methods were employed to identify and recognize each of the qualified trees as a habitat tree, enabling the most favorable evaluation of each. For instance, to identify trees with bird nests, special cameras were utilized alongside human observation. The number per hectare in diameter classes was calculated for all habitat trees in each parcel. Furthermore, the average number and diameter of microhabitat types per hectare were determined across the five study sites.
Results: The findings indicated that the highest frequency per unit area in hollow trees is from the stem and roots, equating to 10.95 trees per hectare, while the lowest is in trees with witches'-brooms, amounting to 0.55 trees per hectare.
Conclusion: The objective of modifying policies in the management of Hyrcanian forests is to emphasize sustainable management practices, enhance forest protection methods, and conserve the forests’ natural values. These endeavors aim to ensure that forest ecosystems persist in providing a diverse array of services to society, such as recreation, water supply, food, wood, clean air, and carbon sequestration. Accordingly, in the study management units, there exist various types of habitat trees, which exhibit diverse quantities and abundances based on the type, developmental stages, and vegetative stage, and are distributed across different diameter classes.