An Alternative Method for Dating of Wildfire Occurrence from Tree-Ring Cores: A Case Study in Northeastern Asia

Abstract

The tree-ring fire scar stands as a pivotal proxy for reconstructing historical wildfire occurrences, providing invaluable context for comprehending contemporary wildfire activities during the Anthropocene era. Precise identification of fire scars often necessitates sampling complete tree disks. Yet, stringent forest resource protection policies limit such collection in certain regions, thus curtailing the application of tree-ring-based fire reconstruction. While current methods based on tree-ring cores can ascertain the age range of fire events, pinpointing the exact year remains challenging. In this study, we propose a novel approach for detecting fire occurrence years by recognizing abrupt shifts in the tree-ring geometric center (TRGC). This method entails extracting a minimum of three tree-ring cores from the uninjured side of the tree and in proximity to the fire scar. We validated this method’s efficacy using samples from Transbaikal of Russia, in northeastern Asia, where fire years have already been documented. Our results show that this method accurately identified the fire year in nine fire scars with a 67 percent probability of exact agreement with the actual fire year. It is noteworthy that this method particularly excels in cases of trees with a single fire scar. We recommend employing the traditional method of collecting tree-ring cores near the fire scar to establish the age range of the fire scar. Subsequently, within this determined range, we suggest detecting the shifts in the TRGC to accurately pinpoint the exact year of the fire scar.