Comparison of Satellite and Drone-Based Images at Two Spatial Scales to Evaluate Vegetation Regeneration after Post-Fire Treatments in a Mediterranean Forest

Jose Luis Martinez,David Hernández,Pedro Antonio Plaza-Alvarez,Manuel Esteban Lucas-Borja,Miguel Angel Moreno,Pietro Denisi,Demetrio Antonio Zema,Javier González-Romero

doi:10.3390/app11125423

Jose Luis Martinez, David Hernández + Show 6 more

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https://doi.org/10.3390/app11125423

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Abstract

The evaluation of vegetation cover after post-fire treatments of burned lands is important for forest managers to restore soil quality and plant biodiversity in burned ecosystems. Unfortunately, this evaluation may be time consuming and expensive, requiring much fieldwork for surveys. The use of remote sensing, which makes these evaluation activities quicker and easier, have rarely been carried out in the Mediterranean forests, subjected to wildfire and post-fire stabilization techniques. To fill this gap, this study evaluates the feasibility of satellite (using LANDSAT8 images) and drone surveys to evaluate changes in vegetation cover and composition after wildfire and two hillslope stabilization treatments (log erosion barriers, LEBs, and contour-felled log debris, CFDs) in a forest of Central Eastern Spain. Surveys by drone were able to detect the variability of vegetation cover among burned and unburned areas through the Visible Atmospherically Resistant Index (VARI), but gave unrealistic results when the effectiveness of a post-fire treatment must be evaluated. LANDSAT8 images may be instead misleading to evaluate the changes in land cover after wildfire and post-fire treatments, due to the lack of correlation between VARI and vegetation cover. The spatial analysis has shown that: (i) the post-fire restoration strategy of landscape managers that have prioritized steeper slopes for treatments was successful; (ii) vegetation growth, at least in the experimental conditions, played a limited influence on soil surface conditions, since no significant increases in terrain roughness were detected in treated areas.

Highlights

Wildfires can negatively affect soil fertility, biodiversity, land resources, global warming, and human assets; positive environmental effects are recognized, such as increased forest regeneration and nutrient recycling [1]
The current study evaluates the ability of Visible Atmospherically Resistant Index (VARI), estimated by both satellite and UAV images, to quantify the vegetation recovery after post-fire treatments (LEBs and contour-felled log debris (CFD)) in a Mediterranean forest of Central Eastern Spain
The surveys of vegetation cover using fieldwork and remote sensing in lands burned by wildfire in a Mediterranean forest showed that:

Summary

Introduction

Wildfires can negatively affect soil fertility, biodiversity, land resources, global warming, and human assets; positive environmental effects are recognized, such as increased forest regeneration and nutrient recycling [1]. The Mediterranean ecosystems are adapted to fire disturbance, but the increasing recurrence and high severity of wildfires generate high soil loss and reduce the ability of vegetation to recover [2]. In the Mediterranean Basin, wildfires burn large forest areas during summer, and in mid seasons, when heavy rainstorms may occur [3,4]. In Spain, even though the number of wildfires has followed a decreasing trend in the last decades [5], wildland is still severely affected by forest wildfires in summer.

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