Field measurements of moisture content of dead leaves of Pinus pinaster (2014-2023)

The Association for the Development of Industrial Aerodynamics - Forest Fire Research Centre (ADAI-CEIF) has developed a daily measurement program for the moisture content of a set of representative fine fuels in forests of Central Portugal since 1987. The sampling site is located is in Lousã, and samples are collected daily during the main fire season (15^th of May - 15^th of October) and twice a week for the rest of the year. These samples are then analyzed at the Laboratory for Forest Fire Studies (LEIF), located less than 1km from the sampling plot.

As part of a study named "The role of field measurements of fine dead fuels moisture content in the Canadian Fire Weather Index System – a case study in the Central Region of Portugal" (https://doi.org/10.3390/f15081429) we present the field measurements of surface litter (Pinus pinaster) carried out from 2014 to 2023. Based on this dataset, the study proposes a correction for the moisture factor (m_f) in the Fine Fuel Moisture Code (FFMC) of the Canadian Fire Weather Index System (CFWIS). This moisture correction was used to directly determine the Initial Spread Index (ISI) and, subsequently, the Fire Weather Index (FWI).

Acknowledgments:

We gratefully acknowledge the researchers and laboratory technicians of the ADAI-CEIF team, who dedicated part of their time to the field collection of samples to determine the moisture content of forest fuels in Lousã (Coimbra, Portugal). In particular, we would like to thank the MCFIRE project (PCIF/MPG/0108/2017, https://mcfire.adai.pt/) for coordinating and supporting these measurements from 2019 to 2023. We also gratefully acknowledge the ongoing efforts of Nuno Luís and João Carvalho in ensuring the collection and processing of samples in the laboratory.