نوع مقاله : علمی - پژوهشی
نویسندگان
1 دانشجوی دکتری، گروه علوم جنگل، دانشکده کشاورزی، دانشگاه ایلام، ایلام، ایران
2 استاد، گروه علوم جنگل، دانشکده کشاورزی، دانشگاه ایلام، ایلام، ایران
3 دانشیار پژوهش، مؤسسه تحقیقات جنگلها و مراتع کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
4 استاد، گروه جنگلداری، دانشکده منابع طبیعی، دانشگاه علوم کشاورزی و منابع طبیعی ساری، مازندران، ایران
5 استادیار، گروه مرتع و آبخیزداری، دانشکده کشاورزی، دانشگاه ایلام، ایلام، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: In recent years, tree-related microhabitats have received increasing attention as a key component in the conservation of forest biodiversity. These microhabitats, which develop as morphological features on living trees or standing deadwood, play an essential role in providing habitat for a wide range of organisms and in maintaining forest ecological functions. Their formation is primarily driven by natural processes such as fungal activity, woodpecker excavation, and physical damage, and by increasing structural complexity they enhance overall forest habitat suitability. Consequently, the conservation of habitat trees is a fundamental element of sustainable forest management. The aim of this study was to investigate the diversity, composition, and occurrence probability of tree-related microhabitats at the degradation developmental stage of beech forests in northern Iran.
Material and Methods: This study was conducted in two one-hectare plots representing the degradation developmental stage in beech forests of the Shafaroud area in Gilan Province and the Sika area in eastern Mazandaran Province. Both plots are under the supervision of the Research Institute of Forests and Rangelands of Iran and are located within unmanaged, unharvested stands (control plots). In each plot, topographic variables including slope and aspect were measured using a clinometer and compass, and all trees were inventoried by species and diameter at breast height (DBH). Tree-related microhabitats were identified and recorded using a standardized microhabitat typology comprising seven main forms, 15 groups, and 47 microhabitat types. All living trees and standing dead trees were systematically surveyed, from the root collar to the crown, first with the naked eye and subsequently—particularly for elevated and sun-exposed parts—using binoculars. All observed microhabitats were recorded for each tree using unique codes. Logistic regression was applied to analyze the occurrence probability of different microhabitat types, while microhabitat diversity was compared using Hill numbers and rarefaction–extrapolation curves after standardization for sample size.
Results: The results indicated that Oriental beech was the dominant species in both study areas, accounting for 86.5% of the trees in Sika and 88.8% in Shafaroud. The mean DBH of beech trees differed significantly between the two sites; however, no significant difference was observed in the number of microhabitats per beech tree. A total of 455 tree-related microhabitats were recorded on beech trees in Sika and 442 in Shafaroud, corresponding to an average of 2.4 and 2.1 microhabitats per beech tree, respectively. In both areas, basal cavities represented the most frequent microhabitat form. Regarding microhabitat types, mosses, trunk rot cavities, and basal cavities were the most abundant, with 174, 146, and 118 records, respectively. The probability of occurrence of mosses was significantly higher in Shafaroud than in Sika, whereas no significant difference was found between the two areas for trunk rot cavities. For trees with a DBH of less than 50 cm, the probability of basal cavity occurrence was higher in Shafaroud, while no significant differences were detected at larger diameter classes. Comparison of overall microhabitat diversity revealed no significant difference between the two sites; however, diversity indices indicated that the diversity of common microhabitats (q = 1) in Sika was approximately twice, and the diversity of dominant microhabitats (q = 2) nearly three times, that of Shafaroud. These findings underscore the importance of considering microhabitat structure in the management and conservation of beech forests in northern Iran.
Conclusion: This study highlights the critical role of tree-related microhabitats in sustaining biodiversity in Hyrcanian forests. By improving our understanding of the relationships between forest structure and tree-related microhabitats, more effective conservation and management strategies can be developed. Based on the results, the Sika site shows considerable potential as a model area for biodiversity conservation. Finally, long-term investigations of tree-related microhabitats are recommended to achieve a comprehensive understanding of ecological processes and their impacts on biodiversity. Further research is also needed to examine the relationships between environmental conditions, forest structure, and tree-related microhabitats in order to provide a more robust scientific basis for conservation planning.
کلیدواژهها [English]
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