Evaluation of the Performance of Climatic Scenarios in the Basal Area Model of Trees (Case Study: the Farim Forest)

Extended Abstract Background: Currently, forests are not only considered an economic pole but also a support for the survival of other sectors. For this reason, decision-making, as the core of management, is an inseparable part of the tasks of managers and planners in natural resource units. Forest management planning is an important decision-making tool in forestry. The result is a management plan that defines the expected activities, their timing, and their control to achieve the objectives of forest management in a forested area. However, climate change over time affects the biological and ecological conditions of plant communities. Considering the importance of sustainable development, it is necessary to pay attention to this issue to offer solutions to adapt to these changes and reduce the risks. Global climate change is increasing with the rise in temperature and atmospheric carbon dioxide levels, as well as changes in precipitation. These changes also affect forest ecosystem services, growth, harvest patterns, and forest structure, posing new challenges to forest ecosystems. Predicting the future growth of forests and their performance under different scenarios is a key element in planning sustainable forest management. It is also essential to study and model the quantitative characteristics of forests to target the ecosystem toward desirable goals and implement conservation and restoration measures. Therefore, this study aimed to evaluate the basal area growth model of trees under climatic conditions for the next five decades. Methods: This study was conducted in the Jojadeh section of the Farim Forest in Mazandaran Province. This section covers approximately 2803 hectares with elevations between 782 and 1750 m above sea level. The climate of the region was classified as humid according to the Ivanov method. The annual rainfall and average annual temperature are approximately 833 mm and 11 °C, respectively. Forest species include Fagus orientalis, Carpinus betulus, Alnus subcordata, Quercus castaneifolia, Acer velutinum and other species. In this study, circular fixed sample plots (1 are) were established and measured in the deciduous and uneven‑aged Farim forest. A 200 m × 150 m rectangular census was established in the forest. The diameter and tree species of all living trees with a diameter of more than 12.5 cm were measured with calipers. The basal areas of both the trees and thickest trees were two important competitive factors used as indepen