Abstract
Satellite based remote sensing technologies and Geographical Information Systems (GIS) present operable and cost-effective solutions for mapping fires and observing post-fire regeneration. Mersin-Gülnar wildfire, which occurred in August 2008 in Turkey, selected as study site. The fire was devastating and continued 55 days. According to Turkish General Directorate of Forestry reports, it caused two deaths and left hundreds of people homeless. The aim of this study is to determine the fire severity and monitor vegetation recovery with using multitemporal spectral indices together with topographical factors. Pre-fire and post-fire Landsat ETM+ images were obtained to assess the related fire severity with using the widely-used differenced Normalized Burn Ratio (dNBR) algorithm. Also, the Normalized Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) were used to determine vegetation regeneration dynamics for a period of six consecutive years. In addition, aspect image derived from Aster Global Digital Elevation Model (GDEM) were used to determine vegetation regeneration regime of the study area. Results showed that 5388 ha of area burned with moderate to high severity damage. As expected, NDVI and SAVI values distinctly declined post-fire and then began to increase in the coming years. Mean NDVI value of burned area changed from 0.48 to 0.17 due to wildfire, whilst mean SAVI value changed from 0.61 to 0.26. Re-growth rates calculated for NDVI and SAVI 57% and 63% respectively, six years after the fire. Moreover, NDVI and SAVI were estimated six consecutive year period by taking into consideration east, south, north and west facing slopes. Analysis showed that north-facing and east-facing slopes have higher regeneration rates in compared to other aspects. This study serves as a window to an understanding of the process of fire severity and vegetation regeneration that is vital in wildfire management systems.
Highlights
Forests covering around 30% of Earth’s surface provide vital organic infrastructure for ecosystem and environmental balance
Burn severity map produced with the Normalized Burn Ratio (NBR) and differenced Normalized Burn Ratio (dNBR) indices was classified into four major classes: low severity (LS), moderate-low severity (MLS), moderate-high severity (MHS) and high severity (HS) (Figure 2)
The Normalized Vegetation Index (NDVI) and Soil Adjusted Vegetation Index (SAVI) values calculated for different dates and the regarding descriptive statistics for the burn scars are demonstrated in Table 2 and 3, respectively
Summary
Forests covering around 30% of Earth’s surface provide vital organic infrastructure for ecosystem and environmental balance. They contribute to genetic diversification and climate regulation. It is a well-known fact that global forest cover has decreased sharply during the last two decades and correspondingly deforestation and forest degradation increase in anthropogenic emissions of greenhouse gases have increased and led to climate change. Wildfires can be named as an important reason for the degradation of forests. They are uncontrolled fires that take places generally in countryside or wilderness area. Chemical and biological damages on ecosystem and modify spectral and spatial characteristics of nature
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