A System Dynamics Model Examining Alternative Wildfire Response Policies

Abstract

In this paper, we develop a systems dynamics model of a coupled human and natural fire-prone system to evaluate changes in wildfire response policy. A primary motivation is exploring the implications of expanding the pace and scale of using wildfires as a forest restoration tool. We implement a model of a forested system composed of multiple successional classes, each with different structural characteristics and propensities for burning at high severity. We then simulate a range of alternative wildfire response policies, which are defined as the combination of a target burn rate (or inversely, the mean fire return interval) and a predefined transition period to reach the target return interval. We quantify time paths of forest successional stage distributions, burn severity, and ecological departure, and use departure thresholds to calculate how long it would take various policies to restore forest conditions. Furthermore, we explore policy resistance where excessive rates of high burn severity in the policy transition period lead to a reversion to fire exclusion policies. Establishing higher burn rate targets shifted vegetation structural and successional classes towards reference conditions and suggests that it may be possible to expand the application of wildfires as a restoration tool. The results also suggest that managers may be best served by adopting strategies that define aggressive burn rate targets but by implementing policy changes slowly over time.

Responses of Plant Biomass in the Brazilian Savanna to Frequent Fires

“…We use the method of System Dynamics to combine qualitative analysis with quantitative analysis (Angerhofer and Angelides, 2000;Duggan, 2016). This method is widely used to describe the mechanism of a disturbance using a dynamic view, thus analyzing the relationships and links between various factors caused by the disturbance, as well as the consequences of these factors on the event over time (Godde et al, 2019;Thompson et al, 2019). We used the system dynamics simulation software Vensim (2017) to simulate these processes.…”

“…System Dynamics (SD) is a modeling tool that integrates multiple mathematical equations to describe the general behavior of a system and is used with a view to unifying empirical knowledge (Angerhofer and Angelides, 2000;Duggan, 2016). SD can be used as a quantitative modeling tool for analyzing the impact of recurrent disturbances such as fire, in complex dynamic systems over time (Collins et al, 2013;Yan et al, 2016;Godde et al, 2019;Thompson et al, 2019). It also considers essential fire-related processes, such as interdependence between system components, temporal feedback, and the non-immediate responses of each component (Angerhofer and Angelides, 2000;Duggan, 2016).…”