Comparing modeled soil temperature and moisture dynamics during prescribed fires, slash-pile burns and wildfires

Background: Wildfires, prescribed fires and slash-pile burns are disturbances that occur in many terrestrial ecosystems. Such fires produce variable surface heat fluxes causing a spectrum of effects on soil, such as seed mortality, nutrient loss, changes in microbial activity and water repellency. Accurately modeling soil heating is vital to predicting these second-order fire effects. The process-based Massman HMV (Heat–Moisture–Vapor) model incorporates soil water evaporation, heat transport and water vapor movement, and captures the observed rapid evaporation of soil moisture. 

Aims: Improve the Massman HMV model and compare it with Campbell soil heating model using four independent soil temperature datasets collected during burning. 

Methods: The models were evaluated using similar BFD curves against observed temperature and soil moisture using standard statistical methods. 

Key results: Results suggest reasonable agreement between the Massman HMV model and field soil temperature data under various burn scenarios and it was consistently more accurate than the Campbell model. 

Conclusions: The Massman HMV model improved soil heating predictions and provided soil moisture predictions. 

Implications: The Massman HMV model was incorporated in the First Order Fire Effects Model (FOFEM ver. 6.7) with a user-friendly interface that allows managers to assess the heating impacts of fire on soil temperature and moisture.