Management and climate contributions to satellite‐derived active fire trends in the contiguous United States

Hsiao‐Wen Lin,James T Randerson,Dongdong Wang,Jessica L Mccarty,Yufang Jin,G James Collatz,Douglas C Morton,Brendan M Rogers

doi:10.1002/2013jg002382

Abstract

Fires in croplands, plantations, and rangelands contribute significantly to fire emissions in the United States, yet are often overshadowed by wildland fires in efforts to develop inventories or estimate responses to climate change. Here we quantified decadal trends, interannual variability, and seasonality of Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations of active fires (thermal anomalies) as a function of management type in the contiguous U.S. during 2001–2010. We used the Monitoring Trends in Burn Severity database to identify active fires within the perimeter of large wildland fires and land cover maps to identify active fires in croplands. A third class of fires defined as prescribed/other included all residual satellite active fire detections. Large wildland fires were the most variable of all three fire types and had no significant annual trend in the contiguous U.S. during 2001–2010. Active fires in croplands, in contrast, increased at a rate of 3.4% per year. Cropland and prescribed/other fire types combined were responsible for 77% of the total active fire detections within the U.S and were most abundant in the south and southeast. In the west, cropland active fires decreased at a rate of 5.9% per year, likely in response to intensive air quality policies. Potential evaporation was a dominant regulator of the interannual variability of large wildland fires, but had a weaker influence on the other two fire types. Our analysis suggests it may be possible to modify landscape fire emissions within the U.S. by influencing the way fires are used in managed ecosystems.Key PointsWildland, cropland, and prescribed fires had different trends and patternsSensitivity to climate varied with fire typeIntensity of air quality regulation influenced cropland burning trends

Highlights

For over a century, considerable effort has been invested in systematically monitoring and managing fires in the United States, with the aim of minimizing threats to human health and property and maintaining ecosystem function and biodiversity [Pyne, 2001; Stephens and Ruth, 2005]
Active fire detections associated with large wildland fires varied considerably from year to year, with a maximum in 2007 (Figure 3) and a coefficient of variation (CV)
Climate controls for cropland and prescribed/other fires varied across the contiguous U.S (CONUS), with no significant correlations between potential evaporation (PE) and active fires in the Pacific and mountain regions and with positive correlations comparable to those between PE and large wildland fires in the southeast

Summary

Introduction

Considerable effort has been invested in systematically monitoring and managing fires in the United States, with the aim of minimizing threats to human health and property and maintaining ecosystem function and biodiversity [Pyne, 2001; Stephens and Ruth, 2005]. In turn, modify climate through aerosol and greenhouse gas emissions [Crutzen and Andreae, 1990; Langenfelds et al, 2002; Kasischke et al, 2005] and by changing land surface properties [Amiro et al, 2006; Lyons et al, 2008; Lee et al, 2011; Jin et al, 2012]. These two way climate-fire interactions create the potential for regional and global scale feedbacks, with their magnitude and sign likely varying regionally [e.g., Rogers et al, 2013; Tosca et al, 2013]. With fires playing an important role in modifying many Earth system and ecosystem processes, an important challenge is to understand the role of management and climate in controlling contemporary changes in fire activity

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