Decomposing the Interactions between Fire Severity and Canopy Fuel Structure Using Multi-Temporal, Active, and Passive Remote Sensing Approaches

Nicholas S Skowronski,Timothy A Warner,Michael R Gallagher

doi:10.3390/fire3010007

Nicholas S Skowronski, Timothy A Warner + Show 1 more

Open Access

https://doi.org/10.3390/fire3010007

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Journal: Fire	Publication Date: Mar 10, 2020
Citations: 36	License type: CC BY 4.0

Affiliation: Northern Research Station, West Virginia University

Abstract

Within the realms of both wildland and prescribed fire, an understanding of how fire severity and forest structure interact is critical for improving fuels treatment effectiveness, quantifying the ramifications of wildfires, and improving fire behavior modeling. We integrated high resolution estimates of fire severity with multi-temporal airborne laser scanning data to examine the role that various fuel loading, canopy shape, and other variables had on predicting fire severity for a complex of prescribed fires and one wildfire and how three-dimensional fuels changed as a result of these fires. Fuel loading characteristics were widely variable, and fires were ignited using a several techniques (heading, flanking, and backing), leading to a large amount of variability in fire behavior and subsequent fire effects. Through our analysis, we found that fire severity was linked explicitly to pre-fire fuel loading and structure, particularly in the three-dimensional distribution of fuels. Fire severity was also correlated with post-fire fuel loading, forest structural heterogeneity, and shifted the diversity and abundance of canopy classes within the landscape. This work demonstrates that the vertical distribution of fuel is an important factor and that subtle difference has defined effects on fire behavior and severity.

Highlights

Canopy structure is the vertical and horizontal distribution of plant material in a forested ecosystem and is a driver of many ecosystem functions and processes
The objectives of this study were: (1) to investigate whether pre-fire canopy structure influenced fire severity; (2) to examine how vertical structural heterogeneity was modified across a gradient of fire severities; and (3) to describe landscape-scale changes in spatial patterning of forest structure resulting from fire
In a previous paper [27], we demonstrated that the properties of the WorldView-3 (WV-3) sensor allow for the estimation of burn severity from spectral reflectance in much the same way as burn severity is calculated from Landsat data [41], but at much higher spatial and spectral resolutions

Summary

Introduction

Canopy structure is the vertical and horizontal distribution of plant material in a forested ecosystem and is a driver of many ecosystem functions and processes. Canopy structure influences the distribution of photosynthetic material and its efficiency [1], microclimate [2], stand species dynamics [3], energy balances [4], and species habitat and behavior [5]. In the case of wildland fire, canopy structure influences the fire dynamics directly as fuel and indirectly through its influence on other variables in the fire environment. Structure influences the fire environment, or factors affecting the dynamics of the fire, by influencing wind and energy flow through drag [10] and energy absorption [11].

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