Miranda H. Mockrin

Using structure locations as a basis for mapping the wildland urban interface

The wildland urban interface (WUI) delineates the areas where wildland fire hazard most directly impacts human communities and threatens lives and property, and where houses exert the strongest influence on the natural environment. Housing data are a major problem for WUI mapping. When housing data are zonal, the concept of a WUI neighborhood can be captured easily in a density measure, but variations in zone (census block) size and shape introduce bias. Other housing data are points, so zonal issues are avoided, but the neighborhood character of the WUI is lost if houses are evaluated individually. Our goal was to develop a consistent method to map the WUI that is able to determine where neighborhoods (or clusters of houses) exist, using just housing location and wildland fuel data. We used structure and vegetation maps and a moving window analysis, with various window sizes representing neighborhood sizes, to calculate the neighborhood density of both houses and wildland vegetation. Mapping four distinct areas (in WI, MI, CA and CO) the method resulted in amounts of WUI comparable to those of zonal mapping, but with greater precision. We conclude that this hybrid method is a useful alternative to zonal mapping from the neighborhood to the landscape scale, and results in maps that are better suited to operational fire management (e.g., fuels reduction) needs, while maintaining consistency with conceptual and U.S. policy-specific WUI definitions.

Adapting to wildfire: Rebuilding after home loss

Wildfire management now emphasizes fire-adapted communities that coexist with wildfires, although it is unclear how communities will progress to this goal. Hazards research suggests that response to wildfire—specifically, rebuilding after fire—may be a crucial opportunity for homeowner and community adaptation. We explore rebuilding after the 2010 Fourmile Canyon Fire from Boulder, CO, that destroyed 165 homes, to better understand individual and community adaptation after wildfire. We examined changes in perception of fire risk and structural characteristics and vegetation mitigation of rebuilt homes, to examine how homes, homeowners, and communities changed after fire. We found evidence that adaptation is occurring, as well as evidence that it is not. Overall, rebuilding was slow. More than 3½ years after the fire, only 30% of those who had lost homes had rebuilt. Postfire rebuilding will only change a fraction of homes, but it is a critical process to understand.

Consequences of residential development for biodiversity and human well‐being

Residential development is a leading driver of land-use change, with important implications for biodiversity, ecosystem processes, and human well-being. We reviewed over 500 published scientific articles on the biophysical, economic, and social effects of residential development and open space in the US. We concluded that current knowledge of the effects of this type of development on social and natural systems is inadequate for achieving key objectives of sustainability, including a viable environment, a robust economy, and an equitable society. Most biophysical studies measured species- or population-level responses to development, rather than attempting to understand the mechanisms underlying these responses or the associated ecosystem processes. Economic and social studies were biased toward assessing the values and benefits to individual people, with little attention given to community-level effects. Of the small number of interdisciplinary studies – less than 3% of the total examined – many reported...

The relative impacts of vegetation, topography and spatial arrangement on building loss to wildfires in case studies of California and Colorado

ContextWildfires destroy thousands of buildings every year in the wildland urban interface. However, fire typically only destroys a fraction of the buildings within a given fire perimeter, suggesting more could be done to mitigate risk if we understood how to configure residential landscapes so that both people and buildings could survive fire.ObjectivesOur goal was to understand the relative importance of vegetation, topography and spatial arrangement of buildings on building loss, within the fire’s landscape context.MethodsWe analyzed two fires: one in San Diego, CA and another in Boulder, CO. We analyzed Google Earth historical imagery to digitize buildings exposed to the fires, a geographic information system to measure some of the explanatory variables, and FRAGSTATS to quantify landscape metrics. Using logistic regression we conducted an exhaustive model search to select the best models.ResultsThe type of variables that were important varied across communities. We found complex spatial effects and no single model explained building loss everywhere, but topography and the spatial arrangement of buildings explained most of the variability in building losses. Vegetation connectivity was more important than vegetation type.ConclusionsLocation and spatial arrangement of buildings affect which buildings burn in a wildfire, which is important for urban planning, building siting, landscape design of future development, and to target fire prevention, fuel reduction, and homeowner education efforts in existing communities. Landscape context of buildings and communities is an important aspect of building loss, and if taken into consideration, could help communities adapt to fire.

Rebuilding and new housing development after wildfire

The number of wildland-urban interface communities affected by wildfire is increasing, and both wildfire suppressionandlossesare costly.However, littleisknownaboutpost-wildfireresponsebyhomeowners andcommunities after buildings are lost. Our goal was to characterise rebuilding and new development after wildfires across the conterminous United States. We analysed all wildfires in the conterminous USA from 2000 to 2005. We mapped 42724 buildings, of which 34836 were present before the fire and survived, 3604 were burned, 2403 were post-fire new development, and 1881 were burned and rebuilt. Before the fires, 38440 buildings were present within fire perimeters (surviving plus burned). Within 5 years post-fire, there were 39120 buildings (surviving, rebuilt and new development). Nationally, only 25% of burned homes were rebuilt within 5 years, though rates were higher in the west, the south and Kansas.Newdevelopmentratesinsideversusoutsidefireperimetersweresimilar.Thatthenumberofbuildingsinsidefire perimeters within 5 years post-fire was greater than pre-fire indicated that homeowners are either willing to face wildfire risks or are unaware of them; or that economic incentives to rebuild in the same place outweigh perceived risks. Additional keywords: building digitalisation, fire perimeters, fire-adapted communities, post-wildfire community response, rebuilding patterns, wildland-urban interface.

The 2010 wildland-urban interface of the conterminous United States

The wildland-urban interface (WUI) is the area where structures and other human development meet or intermingle with undeveloped wildland, and it is where wildfires have their greatest impacts on people. Hence the WUI is important for wildfire management. This document and associated maps summarize the extent of the WUI in the conterminous United States in 2010. The maps and summary statistics are designed to inform both national policy and local land management concerning the WUI. The data presented here summarize the 2010 WUI at a national scale and for each of the 48 conterminous States. All products of this assessment—including maps, statistics, and the WUI GIS dataset—are available at http://www.nrs.fs.fed.us/data/WUI. A pdf version of the map included with this publication is available for download (2 MB PDF) A high resolution version of this publication is available for download (100 MB PDF)

Factors related to building loss due to wildfires in the conterminous United States

Wildfire is globally an important ecological disturbance affecting biochemical cycles and vegetation composition, but also puts people and their homes at risk. Suppressing wildfires has detrimental ecological effects and can promote larger and more intense wildfires when fuels accumulate, which increases the threat to buildings in the wildland-urban interface (WUI). Yet, when wildfires occur, typically only a small proportion of the buildings within the fire perimeter are lost, and the question is what determines which buildings burn. Our goal was to examine which factors are related to building loss when a wildfire occurs throughout the United States. We were particularly interested in the relative roles of vegetation, topography, and the spatial arrangement of buildings, and how their respective roles vary among ecoregions. We analyzed all fires that occurred within the conterminous United States from 2000 to 2010 and digitized which buildings were lost and which survived according to Google Earth historical imagery. We modeled the occurrence as well as the percentage of buildings lost within clusters using logistic and linear regression. Overall, variables related to topography and the spatial arrangement of buildings were more frequently present in the best 20 regression models than vegetation-related variables. In other words, specific locations in the landscape have a higher fire risk, and certain development patterns can exacerbate that risk. Fire policies and prevention efforts focused on vegetation management are important, but insufficient to solve current wildfire problems. Furthermore, the factors associated with building loss varied considerably among ecoregions suggesting that fire policy applied uniformly across the United States will not work equally well in all regions and that efforts to adapt communities to wildfires must be regionally tailored.

Places where wildfire potential and social vulnerability coincide in the coterminous United States

The hazards-of-place model posits that vulnerability to environmental hazards depends on both biophysical and social factors. Biophysical factors determine where wildfire potential is elevated, whereas social factors determine where and how people are affected by wildfire. We evaluated place vulnerability to wildfire hazards in the coterminous US. We developed a social vulnerability index using principal component analysis and evaluated it against existing measures of wildfire potential and wildland–urban interface designations. We created maps showing the coincidence of social vulnerability and wildfire potential to identify places according to their vulnerability to wildfire. We found that places with high wildfire potential have, on average, lower social vulnerability than other places, but nearly 10% of all housing in places with high wildfire potential also exhibits high social vulnerability. We summarised our data by states to evaluate trends at a subnational level. Although some regions, such as the South-east, had more housing in places with high wildfire vulnerability, other regions, such as the upper Midwest, exhibited higher rates of vulnerability than expected. Our results can help to inform wildfire prevention, mitigation and recovery planning, as well as reduce wildfire hazards affecting vulnerable places and populations.

Recovery and adaptation after wildfire on the Colorado Front Range (2010-12)

Following the loss of homes to wildfire, when risk has been made apparent, homeowners must decide whether to rebuild, and choose materials and vegetation, while local governments guide recovery and rebuilding. As wildfires are smaller and more localised than other disasters, it is unclear if recovery after wildfire results in policy change and adaptation, decreasing assets at risk, or if recovery encourages reinvestment in hazard-prone areas. We studied three wildfires on the Colorado Front Range from 2010 to 2012 that each destroyed over 150 homes, describing policy response and characterising the built environment after wildfire. In each location, we found some adaptation, through better-mitigated homes and stronger building and vegetation mitigation standards, but also extensive reinvestment in hazard-prone environments, with governmental support. Despite suggestions that disaster can lead to substantial policy change and elevate the role of land-use planning, we saw only modest reforms: local governments did not revise land-use regulations; a statewide task force considered but did not require standards for building and vegetation mitigation; and only one jurisdiction strengthened its building and vegetation mitigation standards. Experiences in Colorado suggest that time after wildfire either does not provide extensive opportunities for adaptation in the built environment, or that these opportunities are easily missed.

Sprawling and diverse: The changing U.S. population and implications for public lands in the 21st Century

Public lands are typically established in recognition of their unique ecological value, yet both ecological and social values of public lands change over time, along with human distribution and land use. These transformations are evident even in developed countries with long histories of public land management, such as the United States. The 20th Century saw dramatic changes in the American population, in distribution and in racial and ethnic diversity, leading to new challenges and new roles for public lands. Our goal with this paper is to review changing demographics and implications for terrestrial protected areas in the U.S. We overview the fundamentals of population change and data, review past trends in population change and housing growth and their impacts on public lands, and then analyze the most recent decade of demographic change (2000-2010) relative to public lands. Discussions of demographic change and public lands commonly focus on the rural West, but we show that the South is also experiencing substantial change in rural areas with public lands, including Hispanic population growth. We identify those places, rural and urban, where demographic change (2000-2010), including diversification and housing growth, coincide with public lands. Understanding the current trends and long-term demographic context for recent changes in populations can help land managers and conservation scientists mitigate the effects of residential development near public lands, serve a more diverse population, and anticipate future population changes.