Fuel moisture content (FMC) is an important fuel property for assessing wildfire hazard, since it influences fuel flammability and fire behavior. The relationship between FMC and fire activity differs among land covers and seems to be a property of each ecosystem. Our objectives were to analyze pre-fire FMC among different land covers and to propose a wildfire hazard classification for the Sierras Chicas in the Chaco Serrano subregion (Argentina), by analyzing pre-fire FMC distributions observed for grasslands, shrublands and forests and using percentiles to establish thresholds. For this purpose, we used a fire database derived from Landsat imagery (30 m) and derived FMC maps every 8 days from 2002 to 2016 using MODIS reflectance products and empirical equations of FMC. Our results indicated that higher FMC constrains the extent of wildfires, whereas at lower FMC there are other factors affecting their size. Extreme and high fire hazard thresholds for grasslands were established at FMC of 55% and 67% respectively, at 72% and 105% for forests and at 106% and 121% for shrublands. Our FMC thresholds were sensitive to detect extreme fire hazard conditions during years with high fire activity in comparison to average conditions. The differences in the distributions of pre-fire FMC among land covers and between ecosystems highlighted the need to locally determine land cover-specific FMC thresholds to assess wildfire hazard. Our wildfire hazard classification applied to FMC maps in an operational framework will contribute to improving early warning systems in the Sierras Chicas. However, moisture alone is not sufficient to represent true fire hazard in Chaco forests and the combination with other variables would provide better hazard assessments. These operational wildfire hazard maps will help to better allocation of fire protective resources to minimize negative impact on people, property and ecosystems. To the best of our knowledge, this is the first study analyzing pre-fire FMC over several fire seasons in a non-Mediterranean ecosystem, aiming at assessing wildfire hazard.

Moisture content of live fuels (LFMC) is one of the main factors determining fuel flammability and, therefore, a key indicator of fire danger. In this study, we modeled the relationship between spectral indices derived from satellite imagery and field estimations of LFMC in the Chaco Serrano subregion; then, we analyzed the relationship between fire danger estimations based on LFMC calculations and fire activity. Empirical LFMC models fitted for grasslands, Chaco Serrano forests, and glossy privet forests may be considered very accurate R ² > 0.80, whereas the model corresponding to shrublands still needs to be improved (R ² = 0.57). Monthly maps of fire danger reflected the occurrence of fires consistently during years of both high and low fire activity. Most fires occurred mainly in areas with high or extreme fire danger, demonstrating a clear relationship between LFMC and fire activity in the Chaco Serrano subregion. Our LFMC models may be useful to assess the spatiotemporal distribution of fire danger in the Chaco Serrano subregion using remote sensing data. The associated fire danger maps represent a valuable tool for improving decision making processes to organize early warning and fire suppression activities.

In 2020, the Sierras of Córdoba suffered the most extreme fire season in recent collective memory, causing severe ecological and socioeconomic damage. In this study, we mapped the fires of 2020 using Sentinel 2 imagery, we compared the season with historical statistics from 1987-2019 in terms of number of fires, burned area, fire size distribution and fire frequency. Additionally, we analyzed fire incidence in areas of ecological value (protected natural areas [PNA], priority areas for biodiversity conservation [CPA] and native forests protected by Federal Law [#26331/07]) and in areas of socioeconomic value (productive and residential lands, considering their tax value). In 2020, nearly 291866 ha burned in the Sierras of Córdoba —becoming the fire season with the second largest burned area in 34 years—, with a record of 5 megafires (≥10000 ha). Many burned areas had fire return intervals from 3 to 9 years on average, constituting as hotspot regions of fire in our study area. Flames affected more than 5% of PNA, 12% of CPA and 12% of forests protected by federal law. Fires affected mainly the rural areas, and to a lesser extent, urban lands with tax values of AR$8677 and 24592 million, respectively. Extreme drought and fuel availability were determinants for the occurrence of megafires, while the pandemic lockdown suggests that fires were not set by negligent urban inhabitants. The damages caused by the 2020 megafires and the possibility of similar scenarios in the future require policies towards an integral management of the fire issue in Córdoba province. En el año 2020, las Sierras de Córdoba registraron la temporada de incendios más extrema de la memoria colectiva reciente, con daños ecológicos y socioeconómicos severos. En este trabajo se cartografiaron los incendios de 2020 utilizando imágenes Sentinel 2, se comparó la temporada con estadísticas históricas en función del número de incendios, la superficie quemada, la distribución del tamaño de los incendios y la frecuencia en relación con el período 1987-2019. También se analizó la incidencia del fuego en áreas de valor ecológico (áreas naturales protegidas [ANP], áreas prioritarias para la conservación [APC] y áreas de bosque nativo protegidas por la Ley de Bosques [Ley Nacional 26331/07]) y en áreas de valor socioeconómico (tierras destinadas a usos productivos y residenciales, considerando su valor fiscal). En 2020 se quemaron 291866 ha en las Sierras de Córdoba, constituyéndose en la segunda temporada de incendios con mayor superficie quemada en 34 años, con 5 megaincendios (≥10000 ha). Muchas áreas quemadas presentaron recurrencias de fuego entre 3 y 9 años en promedio, lo que las hace áreas hotspot de fuego en las sierras. Las llamas afectaron más del 5% del territorio declarado como ANP, 12% de las APC y 12% de los territorios protegidos por la Ley de Bosques. El fuego afectó principalmente parcelas rurales y, en menor medida, urbanas, con un valor fiscal de AR$8677 y 24592 millones, respectivamente. La sequía extrema y la disponibilidad de combustible determinaron la ocurrencia de los megaincendios, mientras que el contexto de pandemia —con restricciones a la circulación de personas— sugiere que los incendios no fueron originados por habitantes urbanos negligentes. Los daños ocasionados por los megaincendios y la posibilidad de escenarios similares a futuro demandan avanzar hacia un manejo integral de la problemática del fuego en la provincia de Córdoba.