Assessing the susceptibility of semiarid rangelands to wildfires using Terra MODIS and Landsat Thematic Mapper data

Abstract

In order to monitor wildfires at broad spatial scales and with frequent periodicity, satellite remote sensing techniques have been used in many studies. Rangeland susceptibility to wildfires closely relates to accumulated fuel load. The normalised difference vegetation index (NDVI) and fraction of photosynthetically active radiation (fPAR) are key variables used by many ecological models to estimate biomass and vegetation productivity. Subsequently, both NDVI and fPAR data have become an indirect means of deriving fuel load information. For these reasons, NDVI and fPAR, derived from the Moderate Resolution Imaging Spectroradiometer on-board Terra and Landsat Thematic Mapper imagery, were used to represent prefire vegetation changes in fuel load preceding the Millennial and Crystal Fires of 2000 and 2006 in the rangelands of south-east Idaho respectively. NDVI and fPAR change maps were calculated between active growth and late-summer senescence periods and compared with precipitation, temperature, forage biomass and percentage ground cover data. The results indicate that NDVI and fPAR value changes 2 years before the fire were greater than those 1 year before fire as an abundance of grasses existed 2 years before each wildfire based on field forage biomass sampling. NDVI and fPAR have direct implication for the assessment of prefire vegetation change. Therefore, rangeland susceptibility to wildfire may be estimated using NDVI and fPAR change analysis. Furthermore, fPAR change data may be included as an input source for early fire warning models, and may increase the accuracy and efficiency of fire and fuel load management in semiarid rangelands.

Focos de calor registrados en el este del Chaco durante el período 2015-2020. Implicancia ambiental y manejo del fuego

“…Gran parte de los focos detectados obedece a esa situación. Como menciona Landi (2018, p. 78), el pastizal no solo posee características opuestas a las del bosque en cuanto a inflamabilidad y combustibilidad (Jaureguiberry et al, 2011), sino que además es una cobertura que se distingue por presentar fuertes variaciones interanuales de la cantidad de biomasa en respuesta a las condiciones ambientales (Chen et al, 2011). Por otra parte, muchos de los otros focos de calor están relacionados con la quema de microbasurales en zonas urbanas y periurbanas, lo cual denota una clara falta de cultura ambiental.…”

Influence of fuel conditions on the occurrence, propagation and duration of wildland fires: A regional approach

“…The significant higher values of these vegetation indices in burned sites suggested that a higher buildup of fuel stocks during the previous year favored the onset of fires. Several studies have shown the sensitivity of vegetation indices, such as NDVI, to detect the active biomass accumulated in prairies, grasslands, savannas, among others (Moreau et al, 2003, Chen et al, 2011, and to demonstrate that the accumulated vegetation biomass correspond to high fuel load, and this variable is directly related with the fire risk. In our area, increased levels of NDVI-I in burned sites of shrublands and steppes are predictable because wildfires are mainly caused by humans with the goal of reducing the buildup of biomass and to promote vegetation re-growth for livestock.…”

Strata-based forest fuel classification for wild fire hazard assessment using terrestrial LiDAR

“…8,9 However, these direct measurements are time and labor intensive. [10][11][12][13][14] An Australian bushfire study, Project Vesta, identified the importance of fuel structural characteristics in determining fire behavior and ease of suppression, rather than fine fuel load. 1 Fuel structure is comprised of five layers based on their horizontal arrangement and vertical position in the forest profile, including canopy fuels, shrubby elevated fuels, nearsurface fuels, litter fuels (surface fuels), and bark fuels.…”