Forest fire scar detection in the boreal forest with multitemporal spot-vegetation data

Abstract

Abstract-Disturbance events, such as fire, have a major impact on boreal forest dynamics, succession and the global carbon cycle. Methods using satellite imagery are well established for detecting forest fires in real time and mapping the burned area (fire scars) within one year of the fire. This paper focuses on the detection of older fire disturbance-regeneration patterns in the boreal forests of Canada. Previous work found that shortwave-infrared image segmentation proved particularly good at creating uniform regions that were easy to associate with fire scars. Our findings suggest it is possible to detect fire scars up to 10 years old using SPOT VEGETATION data from a single year and that the use of a vegetation index based on near-and shortwave-infrared reflectance is critical to this success. We demonstrate how the use of short term multi-temporal imagery can enhance segmentation results and present a threshold-based procedure for a-posteriori identification of fire scar segments. The resulting fire scar probability map showed a good correspondence with records of fire scars mapped by the Canadian Forest Service for 1980 -1992 and 'hot spots' from the FireM3 Information System for 1994-1998. Index Terms-forest fire scars, image segmentation, multitemporal remote sensing, shortwave-infrared.

Relative suitability of indices derived from Landsat ETM+ and SPOT 5 for detecting fire severity in sagebrush steppe

“…Vegetation indices may be used to detect biomass change and thereby map burn areas and estimate fire severity (Santos et al, 1999) such as the normalized difference vegetation index (NDVI) (Flasse et al, 2004;Roy, 1999;RuizGallardo et al, 2004;van Wagtendonk et al, 2004;Salvador et al, 2000), soil adjusted vegetation index (SAVI; Huete, 1988;, modified soil adjusted vegetation index (MSAVI; Qi et al, 1994;, atmospherically resistant vegetation index (ARVI; Kaufman and Tanre, 1992;Santos et al, 1999), and normalized difference shortwave infrared (NDSWIR; Gerard et al, 2003). Alteration of the vegetation:soil balance is a substantial characteristic of fire; therefore soil adjustments in vegetation indices (e.g.…”

“…human bias). In addition, Gerard et al (2003) developed an algorithm termed the normalized difference SWIR (NDSWIR, Eq. (4)) to map fire scar burns using SPOT NIR (band 3, 0.78-0.89 mm) and SWIR (band 4, 1.58-1.75 mm).…”

Retrospective mapping of burnt areas in Central Siberia using a modification of the normalised difference water index

“…An extensive review of the different types of imagery and approaches used and the available operational products is given in Gerard et al (2003). More recently developed approaches are the burnt area approach of Roy et al (2002), implemented to produce the Moderate Resolution Imaging Spectroradiometer (MODIS) Burnt Area product, and the contextual algorithm of adopted for the MODIS active fire detection.…”

“…For the boreal forest, this increased SWIR remains for the many years after the disturbance that the canopy needs to approach it's original state. Fraser et al (2000a) and Gerard et al (2003) then combined the SWIR with the NIR, which drops after a fire, to form a vegetation index, the Normalised Difference Short-Wave Infrared Index, (NDSWIR = (R nir − R swir )/(R nir + R swir )), which has a close association with burnt areas of varying age, but found that burnt areas created more than 10 years before image acquisition could not be reliably detected. The Gerard method applied an NDSWIR threshold for an a posteriori assignment of burnt areas and produces a burnt area probability map.…”

Simulating Changes in Fires and Ecology of the 21st Century Eurasian Boreal Forests of Siberia

“…Millions of hectares of boreal vegetation are destroyed by wildfires annually [6]. Wildfires affect an ecosystem through a multitude of processes, including a large initial carbon pulse to the atmosphere, decreased surface and (charred) vegetation albedo in the short term (years; [7]), followed by increased albedo Table 1. Fire tolerance is used to determine which species survive a ground fire.…”