Wildfires reshape landscapes, both to the benefit and detriment of impacted areas. After the smoke clears, they can continue to cause hazards like flooding and erosion, while also promoting ecosystem renewal. With an impartial lens, USGS researchers study postfire landscape response and apply our expertise to help mitigate risk and protect people and property.
By the USGS:
Wildfires have long played a crucial role in reshaping and rejuvenating landscapes. They can clear out dead vegetation, return nutrients to the soil, and promote the growth of diverse plant species. However, the aftermath of wildfires also brings significant changes to the environment, some of which pose challenges to ecosystems and dangers to local communities. The USGS conducts extensive research to understand these changes and to develop strategies for hazard mitigation and recovery in fire-prone communities.
The Good: The Beneficial Role of Fire in Landscapes
First, let’s discuss “the good” and why wildfires are a natural part of forest and rangeland habitats. While wildfires can have destructive effects, they play a beneficial role in many ecosystems:
- Nutrient Cycling. Fires consume dead and decaying matter, returning nutrients to the soil, which promotes new plant growth.
- Habitat Diversity. By clearing dense vegetation, fires create a mosaic of different habitats, supporting a variety of plant and animal species.
- Pest and Disease Control. Fires can reduce populations of pests and pathogens, contributing to the overall health of forests and grasslands.
The Bad: How Wildfires Alter Landscapes
Next, let’s discuss “the bad” and how wildfires potentially negatively alter the landscape:
- Soil Becomes Water-Repellent. Intense heat from wildfires can cause soils to become hydrophobic, meaning they repel water. This occurs when organic materials in the soil are vaporized by the heat, and upon cooling, these vapors condense and form a waxy coating around soil particles. As a result, rainwater cannot easily penetrate the soil, leading to increased surface runoff and a higher risk of flash flooding.
- Streams Become Polluted. After a wildfire, ash and debris can be washed into nearby rivers and streams during rainfall. This runoff may contain elevated levels of nutrients, sediments, and heavy metals, which can degrade water quality and pose risks to aquatic life and human health. For instance, following Colorado’s 2020 Cameron Peak Fire, water supplies experienced significant contamination, highlighting the long-term impacts wildfires can have on water resources.
- Slopes Become Unstable. Vegetation plays a vital role in stabilizing soil on slopes. When wildfires destroy this vegetation, the roots that bind the soil together decay, increasing the likelihood of landslides and debris flows, especially during subsequent rainstorms. The USGS has developed models to assess and predict these post-wildfire debris-flow hazards, aiding in the development of early warning systems and mitigation strategies.
- Invasive Plants Can Spread. Wildfires can create opportunities for invasive plant species to establish themselves in burned areas. These species often outcompete native vegetation, leading to reduced biodiversity and altered ecosystem functions. The USGS collaborates with land managers to monitor these changes and develop strategies to promote the recovery of native plant communities.
The Ugly: The Future Impacts of Wildfires on Society
Lastly, “the ugly.” Wildfires are not going away. In fact, wildfires in the United States are becoming more frequent, intense, and destructive. Several factors contribute to this trend, including prolonged droughts and increasing urban development in fire-prone areas. Scientists predict that future wildfire seasons will last longer, burn larger areas, and pose even greater challenges for communities, ecosystems, and emergency responders. The increasing severity of wildfires will have profound effects on public safety, public health, and the economy. For example, some ways wildfires will continue to be problematic include:
- More Frequent Disruptions. Longer fire seasons will lead to more evacuations, power outages, and damage to infrastructure. Areas that were once considered safe may now face a growing threat of wildfire.
- Air Quality and Health Concerns. Wildfire smoke contains harmful pollutants that can worsen respiratory illnesses, particularly for children, the elderly, and individuals with preexisting health conditions. Regions far from active fires can still experience dangerous air quality levels due to drifting smoke.
- Economic Costs. Wildfires already cost billions of dollars annually for firefighting efforts, property damage, and lost economic productivity. As fires become more extreme, these costs are expected to rise, placing strain on local, state, and federal budgets.
- Water and Food Security. Wildfires can damage watersheds, leading to long-term impacts on water supply and quality. Agricultural areas near fire zones may also suffer losses, reducing food production and increasing prices.
USGS’s Role in Wildfire Research and Hazard Mitigation
The USGS plays a vital role in helping communities recover from wildfires and prepare for future events. By partnering with federal and state agencies, including the U.S. Forest Service, the Department of the Interior, and state Geological Surveys, the USGS is driving innovation in fire science and management. These partnerships ensure that responders and decision-makers have the best available information to protect lives, property, and natural resources.
The USGS employs more than 100 scientists whose research focuses on fire-related topics, including using high-resolution remote sensing to characterize vegetative fuel loads; applying the latest satellite technology to detect fires and map wildfire perimeters; evaluating best practices to reduce wildfire risks; and assessing post-wildfire flooding and debris-flow hazards. This work also includes creating and sharing best practices to support recovery across landscapes. Together, USGS expertise and monitoring capabilities are greatly improving the safety of first responders and the public-at-large.
Researchers across the USGS are working with the interagency fire community to expand the use of artificial intelligence, machine learning and other rapid-computing capabilities. For example, the USGS uses artificial intelligence with satellite imagery to detect fire boundaries and develop burn severity maps, and to identify distribution and abundance of fire-adapted invasive species like cheatgrass in the Great Basin.
The USGS Wildland Fire Science Strategy aligns with national initiatives as defined in the National Cohesive Wildland Fire Management Strategy. Developed by a broad swath of stakeholders at all levels, the Cohesive Strategy calls for science and management that promote resilient landscapes and fire-adapted communities for safe and effective wildfire responses.
Preparing for the Future
While wildfires are a natural part of many ecosystems, things are changing and society must take proactive steps to protect lives, property, and the environment from the growing wildfire threat. Given the increasing risks, wildfire management strategies must evolve. Investments in forest management, improved building codes, early warning systems, and resilient infrastructure will be crucial in reducing wildfire impacts. The USGS and other agencies will continue to play a key role in researching fire behavior, mapping high-risk areas, and providing vital information to help communities adapt.
Understanding both the positive and negative impacts of wildfires is essential for effective land management. The USGS’s comprehensive research and collaboration with other agencies enhance public safety, inform policy decisions, and promote resilient ecosystems in the face of wildfire events.
As part of the wildfire community, USGS is deeply connected to the people and landscapes we serve. Wildfires often affect our colleagues, friends, and neighbors, underscoring the importance of our mission to provide critical fire science. Each new fire reminds us of our shared responsibility to understand, adapt to, and mitigate wildfire risks in the face of future challenges.
Case Study: The January 2025 Los Angeles Fires
In January 2025, Southern California faced an unprecedented wildfire crisis as extreme Santa Ana winds fueled four large wildfires (the Palisades, Eaton, Hurst, and Kenneth Fires) and dozens of smaller blazes that scorched the region. The fires burned more than 40,000 acres, destroyed 12,000 structures, and led to at least 30 fatalities. Amid this devastation, the USGS delivered essential science and information that supported fire response efforts, assessed postfire hazards, and aided recovery in impacted communities.
The USGS worked alongside federal and state agencies, providing critical tools and information for every stage of the fire management.
- Real-Time Fire Mapping. The USGS National Civil Applications Center generated wildfire boundary maps for the Palisades, Eaton, and Hurst fires. Using satellite imagery, these maps were delivered to Incident Commanders each morning to inform daily firefighting strategies and evacuation plans.
- Ecological Research and Recovery. The USGS Western Ecological Research Center advised land managers on fire behavior and postfire recovery strategies. This included addressing erosion risks, invasive species management, and advising how to use native vegetation to restore burned areas. The Suppression and Planning Actions for Restoring Communities and Species (SPARCS) team collaborated directly with resource managers to assess their needs and provide support.
- Postfire Hazard Assessments. The USGS Geologic Hazards Science Center led assessments of postfire debris flow risks in the steep terrain of the Santa Monica Mountains. Working with the California Geological Survey and other partners, USGS scientists mapped soil burn severity and modelled the likelihood and volume of debris flows during future storms. This data will help the National Weather Service issue warnings and guide local recovery efforts.
