Epsilon Archive for Student Projects

Abstract

Fire plays a critical role in shaping forest ecosystems, influencing biodiversity, nutrient cycling and
vegetation structure. Understanding the factors that control fire temperature is essential, as fire
strongly affects ecological outcomes such as regeneration and habitat composition. In particular, the
interaction between fuel characteristics, weather conditions and fire temperature remain
insufficiently understood, especially in the oak-dominated forest of Scandinavia.
This study aims to investigate how variations in weather and fuels influence temperature variability
during fires through: (1) calibrating the range of temperatures and respective residence times
observed during experimental fires in oak-dominated forests, (2) evaluating the relative importance
of weather conditions and fuels upon temperature during fires, and (3) ranking different fuel types
in respect to their impact in fire temperatures.
Using a field-based experimental approach, and controlled burns at six locations in southern Sweden
we collected data on fuel composition, fire temperature and concurrent weather variables. Analysis
was made using Principal Component Analysis and Random Forest regression models.
The results show that fuel characteristics, especially the presence and biomass of Calluna (Calluna
vulgaris L.), are the strongest predictors of maximum and cumulative fire temperatures. From 100
g/m2 of Calluna the fire temperatures increased rapidly and plateaued after. The more biomass of
Calluna the higher the fire temperatures were, mainly in the range of 700ºC. Weather variables, such
as relative humidity, mean temperature and wind speed, also influenced temperature but to a lesser
extent. Notably, mid-range humidity levels (55%) were associated with prolonged heat durations,
likely due to increased smoldering.
Results of this study support the development of more flexible and ecologically informed prescribed
burning strategies in Swedish forests through bringing new insights into the complex dynamics
between fuel types, weather and fire temperature.