Spatially-explicit modeling of the intensity of environmental hazards occurrence at the level of forest density classes

The assessment of forest stands' exposure to multiple environmental hazards constitutes a pivotal dimension in vulnerability assessments, serving as the initial stage in comprehensively evaluating the resilience of these ecosystems. Such evaluations, through the quantification and mapping of various environmental hazards, furnish indispensable insights for strategic planning aimed at mitigating forest degradation. Consequently, this study sought to evaluate the exposure of forest stands within the Kooh-e-Dil protected area in Kohgiluyeh and Boyer-Ahmad province of Iran to a suit of environmental hazards.

For modeling and assessing the intensity of multiple hazards, initially, risk maps related to 11 environmental hazards including drought, dust storms, evapotranspiration, wildfires, maximum temperatures, floods, storms, landslides, human presence intensity, soil erosion intensity, and road impact ratio were prepared. Subsequently, employing the Delphi method in conjunction with expert opinion analysis, the relative weight of each environmental hazard was determined. These risk maps were then classified into four classes: low, moderate, high, and very high, and multiplied by the respective relative weights derived from the Delphi method. Consequently, an exposure map for the protected area was generated by averaging the weighted environmental risk maps, subsequently classified into the aforementioned categories. Furthermore, the intensity of exposure for each of the five forest density categories of 1-5%, 5-10%, 10-25%, 25-50% and 50%< to multiple hazards was delineated.

The Delphi method implementation and determination of relative hazard weights indicated that drought (0.151) and wildfires (0.145) carried the highest relative weights, whereas floods (0.043) and landslides (0.036) were of comparatively lower priority. Analysis of the weighted maps and subsequent calculation of exposure intensity maps revealed a range in the index value from 0.116 to 0.276, indicative of spatial variability. Classification of exposure intensity maps highlighted that regions with low intensity were predominantly concentrated in the eastern portion, while those with very high intensity were clustered in the northern and southern segments of the protected area. Notably, forest density class of 1-5% exhibited minimal extent in categories with high and very high intensity (25.1%), yet the highest extent in categories with low and moderate intensity (74.9%) of multiple environmental hazards. Conversely, forest density class of 10-25% demonstrated the highest extent in categories with high and very high intensity (53.7%) and the lowest extent in categories with low and moderate intensity (46.3%) of multiple environmental hazards. Among the total extent of two density classes of 50%< and 25-50%, accounting for more than one-third of the protected area's forests, 49.4% lay within categories with high and very high intensity, while 50.7% fell within categories with low and moderate intensity of multiple environmental hazards.

The escalation of human activities and the ramifications of climate change pose a potential threat, potentially elevating the proportion of high-density forest extent within categories with high and very high intensity of multiple environmental hazards, thereby augmenting the vulnerability of the protected area. The outcomes of this research furnish detailed spatial insights into the exposure intensity of various forest density classes to multiple environmental hazards, thereby facilitating the formulation of targeted protective and supportive measures.