A model‐based approach to wildland fire reconstruction using sediment charcoal records

Abstract

Lake sediment charcoal records are used in paleoecological analyses to reconstruct fire history including the identification of past wildland fires. One challenge of applying sediment charcoal records to infer fire history is the separation of charcoal associated with local fire occurrence and charcoal originating from regional fire activity. Despite a variety of methods to identify local fires from sediment charcoal records, an integrated statistical framework for fire reconstruction is lacking. We develop a Bayesian point process model to estimate probability of fire associated with charcoal counts from individual-lake sediments and estimate mean fire return intervals. A multivariate extension of the model combines records from multiple lakes to reduce uncertainty in local fire identification and estimate a regional mean fire return interval. The univariate and multivariate models are applied to 13 lakes in the Yukon Flats region of Alaska. Both models resulted in similar mean fire return intervals (100-350 years) with reduced uncertainty under the multivariate model due to improved estimation of regional charcoal deposition. The point process model offers an integrated statistical framework for paleo-fire reconstruction and extends existing methods to infer regional fire history from multiple lake records with uncertainty following directly from posterior distributions. keywords paleoecology, fire history, fire return interval, Bayesian hierarchical model, Poisson point process

Changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA

“…Paleoclimate and fire data Wildfire-derived charcoal deposited in lake sediments can be used to identify individual fire events and to estimate fire frequency over hundreds to thousands of years (Itter et al 2017). In combination with sediment pollen records, charcoal records help to determine how vegetation and fire frequency and severity shifted with climatic variability in the past (Gavin et al 2007).…”

Emerging palaeoecological frameworks for elucidating plant dynamics in response to fire and other disturbance

“…For instance, when working with palaeoenvironmental data, Simpson (2018) proposes the implementation of generalized additive models that estimate trends in the data as smooth functions of time, which can address common issues that arise in temporally uneven data (e.g., identifying nonlinear trends and constraining the timing of change). Moreover, multivariate statistical frameworks can also be used on networks of sites that share a common regional fire regime to reduce the individual fire return interval uncertainty for any single record (see Itter et al, 2017).…”

Guidelines for the use and interpretation of palaeofire reconstructions based on various archives and proxies

“…However, only one study has compared the fire histories resulting from these two methods (Oris et al, 2014a). To distinguish local and regional fire events in lake charcoal deposits is not an easy task and constitutes an ongoing research challenge (Itter et al, 2017). Several procedures and numerical analyses are required to isolate fire episodes (Higuera et al, 2007) that could enclose one or more fires occurring in the charcoal source area (Gavin et al, 2007).…”