FireLands 1.0: A landscape evolution model for simulating the effects of fires and post-fire erosion on sediment dynamics in evolving landscapes

Abstract. Wildfires play an important control on changing Earth surface processes across a wide range of landscapes. Although post-fire changes in erosion and deposition dynamics have been widely documented, feedbacks among wildfire, vegetation, sediment dynamics, and topographic adjustment across large temporal and spatial scales remain poorly understood. Landscape evolution models provide a powerful framework for integrating these processes and timescales, enabling assessment of how wildfire influences long‑term landscape evolution. Here, we present FireLands, a landscape evolution model that integrates a newly developed component for fire ignition and spread (WildfireGenerator) with existing components for landscape evolution processes. WildfireGenerator is a cellular automaton model simulating fire ignition and spread, aridity‑controlled fire severity and vegetation regrowth. Within FireLands, WildfireGenerator is coupled with components for soil production, erosion by channelized flow, and hillslope sediment transport. We link wildfire effects to geomorphic process efficiency by positing fire-driven increases in sediment erodibility and hillslope transport efficiency, with the highest increases occurring after high-severity fires. Model testing suggests that WildfireGenerator realistically simulates the effects of fire on vegetation and the emergence of landscape‑scale vegetation patterns. An observed fire magnitude–frequency relationship from Calabria, a wildfire‑prone region in southern Italy, is reproduced with good agreement. Simulations incorporating coupling between wildfire and landscape evolution show that FireLands captures key aspects of post‑wildfire geomorphic response, whereby vegetation controls the magnitude of erosion on hillslopes and deposition within higher-order fluvial channels. The magnitude and spatial extent of sediment redistribution across post‑fire landscapes depend on fire frequency and severity, vegetation recovery rates and landscape heterogeneity. FireLands is able to simulate these dynamics across large spatial and temporal scales, providing a tool for integrating short‑duration, high‑intensity geomorphic extremes driven by wildfire within a long‑term landscape evolution framework. Including fires in a landscape evolution perspective is powerful to understand the effects of fire-vegetation feedbacks on sediment transport over various spatial and temporal scales.