Part 1: Overview
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Over the past century, America’s population has nearly tripled, with much of the growth flowing into traditionally natural areas. This trend has created an extremely complex landscape that has come to be known as the wildland/urban interface. Encroaching development into forests, grasslands and farms has put lives, property and natural resources at risk from wildfires. From 1990 to 2000, the majority of the fastest-growing counties in the U.S. were in areas known to be prone to wildfire.
Since 1970, more than 10,000 homes and 20,000 other structures and facilities have been lost to severe wildfire. A house and its surrounding community can both meet Firewise objectives and be compatible with the area’s ecosystem. Firewise measures can help make homes and landscapes as beautiful as they are safe. Firewise landscaping techniques can actually improve the aesthetic quality of a home by clearing out dry and dead vegetation and allowing space between trees and plants.
The map is from Mapping Census 2000: The Geography of U.S. Diversity, Brewer & Suchan, ESRI Press, 2001. It shows the percent change in total population from 1990 to 2000 (sources-- U.S. Census Bureau, Census 2000; Redistricting Data (PL 94-171) Summary File and 1990 Census; Cartography: Population Division, U.S. Census Bureau)
The map is subdivided by county. The dark blue counties are where there has been a gain in population of 50% to 191%; blue is a gain of 25% to 49.9%; pale blue is a gain of 13.2% to 24.9%; white is a gain of 0.0% to 13.1%; pale yellow is a loss in population of 10% to 0.1%; dark yellow is a loss of 42.3% to 10.1% (the overall trend nationally was a gain in population of 13.2%). The circled areas are the top 15 fastest-growing counties for the decade. According to Jim Smalley, Wildfire Protection Manager at the National Fire Protection Association, at least 10 of those are in areas known to be significantly prone to wildfire.
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When wildfires occur, homes and the landscape interact with natural forces, and the results are often devastating. Of special concern are the areas where dwellings abut forests - often referred to as the wildland-urban interface. As people move into fire-prone areas, their homes, yards and gardens add fuels that can accelerate the spread of wildfire. Homeowners can, however, design their landscapes to slow an advancing fire. In this way, they can participate in protecting their property.
In this section, we'll explore several factors that make wildland-urban interface fires so destructive, including seasonal effects, natural forces, and people. We'll look at fire growth and behavior, and how they are affected by arrangement and type of fuels, the terrain, and wind.
We'll also take a brief look at landscape principles - from site evaluation and plant selection to placement and maintenance - all of which can help protect a home from an advancing wildfire.
In any region fires can be small and slow burning or large and fast burning, depending on the makeup of fuels, topography and weather.