Characterising and managing fire risks to plantations under changing climates

Abstract

Wildfires are a common threat to the sustainability of commercial plantations in fire-prone regions. Large losses of plantations from wildfires can lead to the disruption of forest yield, with flow-on impacts to downstream industries, resulting in significant social and economic impacts to local communities. Future climate projections indicate an increase in wildfire activity, including increases in fire extent, severity or frequency in many fire-prone ecosystems. Land and fire management agencies around the world invest significant resources to reduce the likelihood and impact of future fires and increase the capacity for fire suppression. However, we currently know very little about how commercial plantations will be impacted by fire as the climate changes, or if strategic management can mitigate some of these risks into the future. In this study we sought to quantify fire risks to plantations and nearby community assets under current and changing climates; and to evaluate the effectiveness of management options for mitigating some of these risks under changing climates. This research included the customisation of a fire simulation tool for use in plantation landscapes by developing plantation-specific fuel functions (derived from field-sampling in hardwood and softwood plantations around Australia) that were integrated into fire spread models. To quantify longer-term risks, these advancements were also integrated into a stochastic fire regime simulator (FROST– Fire Regimes and Operation Simulation Tool) that is proposed for future use in operational risk assessments. Fire risks to both environmental and community assets were evaluated under current and changing climates to support evidence-based management to help guide investment, insurance negotiations, and fire mitigation in the plantation sector. The fire regime simulator (FROST) was also used to evaluate a range of different management options for reducing risk as a basis for efficient allocation of fire prevention and response resources both by plantation growers and by broader fire regions. We found that reducing suppression response times (to 15 minutes or less for all ignitions) and the current approach to management (a construction rate of 2km/h for suppression and 15-minute response times, with 4000ha/year of prescribed burning) were consistently the best management strategies for reducing fire risks to plantations and adjacent communities, regardless of the climate model used. These strategies offer the greatest scope for reducing future wildfire risks to plantation assets and adjacent communities as the climate changes. High pruning in strategic locations may also be worthy of future investment but should be considered in combination with more rapid suppression and prescribed burning. Plantation owners currently have little influence over the amount and location of prescribed burning adjacent to plantations, and fuel reduction burning is not regularly undertaken in Australian plantations. Therefore, rapid suppression response times is the single best investment for minimising impact to plantation assets under a hotter or drier climate.