Estimating spatiotemporal dynamics of forest fire hazard using Analytical Hierarchy Process and geostatistical methods in Similipal Biosphere Reserve, India

Anthropogenic factors and climate change induced severe forest fires that are reoccurring globally. Because of the large spatial scale, frequent occurrence, and danger involved with the forest fires, remote sensing-based approaches are best suited to study this phenomenon. However, there are few studies addressing the temporal effects of the various factors associated with the  forest fire. In this work, by using Analytical Hierarchy Process (AHP), a multi-criteria decision support system and geostatistical methods namely Getis-Ord Gi* statstic and Mann Kendall trend test, we have developed a framework to understand the temporal dynamics of forest fire hazard and associated factors by demarcating the hotspots of forest fire using freely available datasets . The proposed framework has been applied on the Similipal Biosphere Reserve (SBR), Odisha, India. With an area of 5569 km², the SBR is the sixth largest biosphere reserve in India, comprising of a national park, bird sancturary, tiger reserve, and elephant corridor. Due to its biodiversity and importance in terms of rich and endemic species of flora and fauna, SBR was brought into the umbrella of world network of biosphere reserve under the Man and Biosphere (MAB) programme of UNESCO in the year 2008. Although being a biosphere of international importance, the SBR annually experiences nearly 12 km² of fire damage.Through this work, the most significant clusters of forest fire hotspots have been demarcated. We have used factors related to topographical, climatic, and physical characteristics of forest to generate forest fire hazard index at annual scale for 28 years (1988 – 2018) using AHP method. The geostatistical methods were applied on the generated annual fire hazard index data to demarcate the zones of emerging hotspots of forest fire. The results indicate that temporally, the trend of forest fire hazard in buffer zone of the area (Similipal Sanctuary) is decreasing, whereas in core area (Similipal National Park), it is increasing and corelates with the temporal trend of vegetation density in the whole area. However, vegetation density and land surface temperature in the core area does not changes significantly with time. The emerging hotspot analysis shows that most of the region (32% of the total area) is exhibiting an oscillating behaviour with respect to the fire hazard over the studied time-period of 28 years, with more than 50% of the years showing increasing trends of fire hazard. A total of 186 km² of the region is persistently a hotspot of fire hazard in studied time-period. Overall, 11% of the study area is either under persistent fire hazard or showing increasing trend of fire hazard. However, in the central part of the SNP, the fire hazard is decreasing with time. The same region also observes intense rain, and this could be a factor for the observed decrement in the fire hazard. The results can be used for mitigating the fire hazard of the SBR, alsothe proposed framework can be applied globally to any region with dense vegetation for fire hazard spatiotemporal assessments.