The risk of wildfire is higher in areas where trees and shrubs have replaced grasses, according to a new study.<\/p>\n
Across the United States over the past decade, an average of over 61,000 wildfires have burned some 7.2 million acres per year.<\/p>\n
Once a wildfire starts spreading, the firefighting task is exacerbated by issues like spot fires, where winds carry lofted\u00a0sparks\u00a0and start new fires outside of the original fire perimeter. The greater the potential spot fire distance, the more difficult wildfires are to monitor, control, and suppress.<\/p>\n
The new study finds that as woody plants like shrubs and trees<\/a> replace herbaceous plants like grasses, spot fires can occur farther away from the original fire perimeter. This \u201cwoody encroachment\u201d is not only a major issue in grasslands where the study takes place, but also in wetland and savanna systems like\u00a0longleaf pine, an important ecosystem<\/a> in Florida.<\/p>\n \u201cSpot fires are one of the most common reasons why houses burn in a wildfire,\u201d says Victoria Donovan, an assistant professor with the School of Forest<\/a>, Fisheries, and Geomatics Sciences at the West Florida Research and Education Center at the University of Florida Institute of Food and Agricultural Sciences (UF\/IFAS).<\/p>\n \u201cIt\u2019s not typically because the flames from wildfire reach a house, but that embers from that fire land on roofs, travel through home ventilation systems, or land on other combustible material on or near the home, and ignite the house from there. They\u2019re a big concern for structural damage.\u201d<\/p>\n The findings indicate that\u00a0prescribed fire, which is commonly used in Florida to control woody plant growth, could help reduce spot fires<\/a>.<\/p>\n The researchers looked at three phases of woody encroachment: the first a largely grassland area, the second grassland with new forested growth, and the third a dense forest.<\/p>\n They modeled the research using a mathematical fire simulation program<\/a> and considered various conditions in Loess Canyons Experimental Landscape in south Nebraska. Donovan conducted this study as a researcher at the University of Nebraska-Lincoln.<\/p>\n \u201cOur study shows that the risk of spot fire is much lower when you\u2019re burning<\/a> under the weather conditions used for prescribed fire, regardless of encroachment phase, compared to waiting for the potentially more extreme conditions we can see during wildfires,\u201d Donovan says.<\/p>\n \u201cThis tells us that using prescribed fire early to control encroachment and reduce fuel load is a lot safer than waiting for a wildfire to occur.\u201d<\/p>\n The safety concerns of woody encroachment extend beyond structures and residents to also include the\u00a0firefighters\u00a0battling the blaze.<\/p>\n \u201cIt is not only spot fire distance that increases wildfire risk from woody encroachment. Shrubs and trees<\/a> can grow much taller than grasses,\u201d Donovan says. \u201cThink about putting out your campfire on the ground by pouring water<\/a> on it, and compare that to trying to put out a fire a couple stories above you.\u201d<\/p>\n The concerns are universal, she says, and reveal similarities no matter the land type where the wildfires occur.<\/p>\n