Surface and Crown Fuels and Wildfire Behavior in Natural and Planted Forests Ecosystem of the Watershed of 25 (Shenroud, Siahkal)

Siahkal forests in northern Iran experienced extended and devastating fire seasons in recent decades, in most cases, driven by dry, warm/hot, windy weather. Identifying forest fuel and wildfire risk dynamics is important for an integrated fire-forest management strategy. To understand how forest structure controls these dynamics, we quantified forest fuels and fire behaviour across different forest types in the study area. In this work, we present the results of an analysis of wildfire behaviour from historical fire records, vegetation type, weather, and fuel moisture. We used a modelling approach to estimate the physical parameters of surface fire behaviour: flame length and fire size; as well as the potential crown fire occurrence. We selected a large forest watershed area in Siahkal County of north Iran, under temperate broadleaf forests and mixed plantations with variable compositions. To run the model, we gathered data on forest structure and composition, and physical information. We detected moderate to high levels of fire size and flame length, ascribed to the high availability of very dry fine biomass. The crown fire potential varied greatly throughout the landscape. Low stands were more prone to crowning. The results show that crown fire potential in plantation stands especially conifers are higher compared to natural stands. In addition, the early stages of planted stands are more likely to experience crown fire due to their low mean height and low CBH. The findings can assist in the identification of priority areas where forest structure needs to be managed.