Frequently Asked Questions (FAQ)

What is burn severity?

In the MTBS project, "burn severity" refers specifically to fire effects on above-ground biomass. The definition is drawn from the reference: NWCG Glossary of Wildland Fire Terms and is based on the term Fire Severity, which is defined as: "Degree to which a site has been altered or disrupted by fire; loosely, a product of fire intensity and residence time."

The following additional statements further clarify the nature of the products developed by this project:

• Burn severity is a composite of first-order effects and second order effects that arise within one growing season.
• Burn severity relates principally to visible changes in living and non-living biomass, fire byproducts (scorch, char, ash), and soil exposure.
• Burn severity occurs on a gradient or ordinal scale.
• Burn severity is a mosaic of effects that occur within a fire perimeter.
• Longer term effects are controlled by variables that evolve after a fire and are beyond the scope of this program.
• Burn severity is mappable and remotely sensed data provide a measurement framework.

What is NBR?

The Normalized Burn Ratio (NBR) is a normalized index that emphasizes the spectral response of fire-affected vegetation by leveraging Landsat near infrared and short-wave infrared bands in an effort to provide the best contrast between photosynthetically healthy and burned vegetation.

What fires are mapped by the MTBS program?

MTBS inventories and maps all known large fires within the United States, regardless of fire origin or type. Fires within the continental U.S. as well as Alaska, Hawaii and Puerto Rico are included. Large fires include those in the western U.S. that are at least 1,000 acres in size and those within the eastern U.S. that are at least 500 acres in size (Alaska and Hawaii are in the western zone, Puerto Rico is in the eastern zone). Known fires are those that are documented in fire occurrence databases ingested by the program (see the FAQ below for more information). Additionally, fires that are observed by mapping analysts during the analysis process are also inventoried and mapped if they meet the size requirement.

How does MTBS know where the fires are located for mapping?

MTBS utilizes existing wildfire and prescribed fire occurrence data collected from state and federal agencies/organizations. Fire occurrence databases with reasonably precise geospatial descriptions (latitude/longitude, legal description, etc.) are compiled and standardized to generate a point location dataset. Core database elements are compiled as a part of this dataset include, but are not limited to, the fire incident ID and name, fire type, reported fire size, date of fire ignition, date of fire containment, date of fire declared out. The MTBS program uses this dataset to support all phases of the fire mapping process (i.e. to determine the appropriate assessment strategy, selection of appropriate satellite image data, association of the fire information with the appropriate burn area identified using remote sensing data, etc.).

Why are some fires missing from the database?

A fire may be missing from the MTBS database for the following reasons:

• The size of the fire was misreported. A 5,000 acre fire may be missed if it is reported as 50 acres.
• Inaccurate reporting of date of ignition, containment, or location may lead to a fire not being assessed at the proper time and location, thus making it unlocatable.
• Poor image quality. Near cloud-free observations of both pre-fire and post-fire imagery are required in order to produce an accurate mapping.
• Fires of very low severity may not be visible in the imagery and thus not possible to delineate or characterize.

How were the particular MTBS fire size thresholds determined?

Due to resource constraints and technical limitations, the MTBS program cannot map every fire that has occurred. Consequently, during the initial planning stages of the MTBS program, analysis of available wildfire occurrence data determined that the proposed size thresholds (>= 500 acres in the eastern United States and >= 1,000 acres in the western United States) would map approximately 95% of the total area burned. These size specifications provide MTBS the ability to meet the monitoring requirements set forth by the program founders within a reasonable cost and timeframe.

What is a revised fire?

A "revised" fire is a modified version of the original geospatial data and mapping products for a mapped MTBS fire. If a need for correction to the original dataset is identified through the MTBS quality control process, the geospatial data and mapping products are revised accordingly and republished. The original MTBS dataset is removed from the data distribution archive.

What do Initial Assessment and Extended Assessment mean?

Each fire that is mapped by MTBS has either an "Initial" or "Extended" assessment strategy. An Initial Assessment relies on post-fire satellite data typically acquired at the first opportunity after the fire in order to capitalize on the maximum post-fire data signal and is used primarily in ecosystems that exhibit rapid post-fire vegetation response (i.e. grass, herbaceous and particular shrubland systems). An Extended Assessment relies on post-fire satellite data typically acquired during the growing season following a fire in order to include any delayed first order fire effects (e.g. initial site response and early secondary effects).

What are the definitions of the fire types in MTBS data?

• Wildfire - An unplanned, unwanted wildland fire including unauthorized human-caused fires, escaped wildland fire use events, escaped prescribed fire projects, and all other wildland fires where the objective is to put the fire out (definition currently under NWCG review).
• Prescribed Fire - Any fire intentionally ignited by management actions in accordance with applicable laws, policies, and regulations to meet specific objectives.
• Wildland Fire Use - An event dealing with the management of a naturally ignited wildland fire to accomplish specific prestated resource management objectives in predefined geographic areas outlined in the Fire Management Plans.
• Unknown - A fire event whose incident type was not reported from the original reporting agency.
• Complex - Two or more individual incidents located in the same general area which are assigned to a single incident commander or unified command.
• Out of Area Response - Multiple resource response to a wildfire incident. This term applies exclusively to wildfire incidents.

What is the citation for MTBS data and reporting products?

What datasets are compiled by MTBS for each fire?

The following geospatial datasets and mapping products are produced for every MTBS fire. File format is noted in parentheses.

• Pre-fire Landsat 30m reflectance image subset (GeoTiff)
• Post-fire Landsat 30m reflectance image subset (GeoTiff)
• 30m dNBR image subset (GeoTiff)
• 30m RdNBR image subset (GeoTiff)
• 30m 6-class thematic burn severity (GeoTiff)
• Burned area perimeter (ESRI shapefile)
• Non-processing area mask (ESRI shapefile)
• FGDC metadata (text/XML)
• Page-sized burn post-fire Landsat image and burn severity map with burn severity statistical summary (PDF)
• Google Earth map with pre/post Landsat image, burn scar boundary and thematic burn severity data (KMZ)
• Statistical summary of burn severity by key GIS layers (dbf)
• Fire table containing key fire occurrence attributes (dbf)

Does the MTBS project provide mosaicked geospatial products?

Yes. Currently, three MTBS datasets are provided as seamless national data products. MTBS burn area boundary polygons and fire occurrence points are each provided as a single nationwide dataset that includes the continental United States (one dataset per state, and collectively), Alaska, Hawaii and Puerto Rico. Thematic burn severity data are also mosaicked to generate annual, seamless burn severity raster layers created individually for the continental United States, Alaska, Hawaii and Puerto Rico. All three of these national datasets can be downloaded from the MTBS Direct Download webpage.

What is the spatial resolution/scale of MTBS data?

All MTBS raster datasets are generated from Landsat (TM/ETM+/OLI) image data which is acquired at a spatial resolution of 30 meters. MTBS vector datasets (burn scar boundaries) are delineated from imagery and burn severity index data at a map scale of 1:24,000 to 1:50,000.

What is the projection/coordinate system of MTBS data?

All MTBS data are provided in Albers Equal Area projection using the regional projection parameters specified below for the continental United States, Alaska, Hawaii and Puerto Rico. User note: the positional accuracy difference between NAD83 and WGS84 is negligible given the resolution/scale of MTBS data.

Why does MTBS use Albers Equal Area projection for its data?

Mapping and image-derived geospatial data for regional and continental scale areas of large east-west extent are typically compiled in an equal area projection. The Albers Equal Area projection is routinely used for data that covers the continental United States or outside the continental United States regions, including Alaska, Hawaii and Puerto Rico.

MTBS uses unique Albers Equal Area projection parameters that are published for each of these geographic regions. Data practitioners may reproject data and change the projection parameters in the process to address project needs (i.e., minimize distortion for an area of interest, maintain positive map coordinate values, etc.). Other related national mapping programs that provide data at similar spatial resolution and extent as MTBS, such as LANDFIRE and the National Land Cover Database (NLCD), also publish their data products using Albers Equal Area projection. MTBS, LANDFIRE and NLCD all deliver their data using the same Albers Equal Area projection parameters. This enables users to conveniently integrate these data for visualization and analysis.

To provide flexibility and better meet the needs of end users, the MTBS Program is taking steps to develop and implement new data management and dissemination technologies. When available, these capabilities will allow end users to extract and download data using a desired projection selected from a set of standard projections.

How does MTBS determine the thematic burn severity classes?

Thresholding continuous burn severity index data into thematic burn severity classes is a considerable technical procedure and varies slightly between fires in different ecological settings. A technical description of the thresholding process is documented in recent MTBS Project Reports and the paper "A Project for Monitoring Trends in Burn Severity".

Are MTBS burn severity data field validated?

No.

Can I customize the burn severity data for my fire(s) of interest?

Yes. For each MTBS fire, the continuous burn severity index, the dNBR, is provided. The continuous burn severity thresholds selected by MTBS to identify the respective thematic burn severity classes are published as part of the metadata. To customize the burn severity thresholds established by MTBS and create a thematic burn severity product more applicable to local resource management needs, users have the option of gathering additional ground-based information and local knowledge, which may result in different thresholds than those established by MTBS.

What is the composite burn index?

The composite burn index, or CBI, is a field-based protocol that estimates the ecological effects of fire on individual strata within a plot or site in a burned area. The composite state of these post-fire conditions are collectively related to the signal detected by moderate resolution satellite data.

Is composite burn index data available for all fires?

No. However, thousands of composite burn index (CBI) plot data have been collected for a number of fires. The MTBS project is coordinating with project collaborators to compile the available CBI plot data into a single database for access by users.

What are the MTBS thematic burn severity data class descriptions?

• Increased Greenness - Areas that burned but display more vegetation cover, density, and/or productivity (vigor), usually within one growing season after fire. This is a fire-caused effect from release of nutrients into soil, and/or reduced competition for nutrients, light and water (much like a thinning effect). These areas are usually herbaceous or low shrub communities that undergo little change in species composition after fire.
• Unburned to Low - Areas that are either unburned, or when visible fire effects occupy a small proportion of the site, on the order of less than 5 percent. If more of the site is burned, then effects are limited to a few biophysical components. The class may also include areas that recover very quickly after fire, such as grasslands or light surface burns under dense, non-impacted forest canopies.
• Low - Areas where more than a small proportion of the site burned. Collectively, all strata are slightly altered from the pre-fire state. Duff, woody debris and newly exposed mineral soil typically exhibit some change. Low vegetation (<1 meter) and shrubs or trees (1-5 meters) may show significant aboveground scorch, char or consumption, and vegetation density or cover may be greatly altered. These prefire plants are generally still viable and recover quickly (within a year or two), with little change in species composition. An exception is western conifers, where sapling-sized trees may exhibit 50 percent or more mortality. Intermediate and large overstory trees may exhibit up to 25 percent mortality evidenced by crown char or scorch. Where charring does not kill tree crowns, as is common in the southeast, higher percentages of black char may occur. Char height from ground flames is typically less than 3 meters.
• Moderate - The moderate class is difficult if not impossible to briefly describe. Indicators may be fairly consistent across biophysical strata and will exhibit traits between the low and high severity classes. On the other hand, numerous potential combinations of distinct low and high indicators may occur to yield a moderate classification overall within the minimum mapping unit. Conditions are transitional in magnitude and/or uniformity between the low and high characteristics described.
• High - This class is characterized by fairly consistent effects across a site. In forested ecosystems, litter is totally consumed; duff is typically nearly entirely consumed. Medium and heavy woody debris are at least partially consumed and at least deeply charred with mostly ash and charcoal remaining. Overstory trees typically exhibit greater than 75 percent mortality. Biomass consumption and above-ground changes in carbon balances are significant. Crown char is frequently 100 percent from torching fire, and significant branch loss is evident at the highest crown levels. Where crown torching did not occur, char height from ground flames often exceeds 4 meters. Overstory tree effects are generally long lasting. New tree establishment may occur 1-3 years post-fire, but forest development often takes many decades. Herbaceous plants and shrubs are almost completely charred or consumed above ground, often with notable branch loss on taller shrubs, which may be reduced to small stubs. Resprouting from perennial plants, except grasses, is strongly reduced, as most individuals lose viability with a significant reduction in cover.

Are MTBS burn area boundaries the same as incident perimeters?

MTBS burn area boundaries are delineated from interpretation of post-fire Landsat reflectance imagery and continuous burn severity indices derived from Landsat. Data and methods used to delineate incident perimeters are highly variable and may include both ground based and airborne/satellite image data. Consequently, MTBS burn area boundaries and incident perimeters may not have complete correspondence. Some examples of how differences can be explained include:

• MTBS burn area delineations may not include surface burns that are not visible because they occur under unburned vegetation canopies. These areas may or may not be included in incident perimeters depending ground-based information was available.
• MTBS burn area boundaries do not delineate unburned islands within the fire area whereas incident perimeters typically do, at least for larger unburned islands.
• Incident perimeters may be delineated to the extent of fire containment lines. Fires may or may not actually extend to containment lines in some cases resulting in overestimates of fire area.

What are the "stripes" that appear on some MTBS thematic burn severity datasets?

These areas are part of the "Non-processing area" class and are data gaps within a Landsat 7 SLC-off reflectance imagery used in the MTBS fire mapping process for that fire. The Landsat 7 SLC-off product is further described by the USGS Landsat Project.

How often is new MTBS data released?

New geospatial fire data and reporting data are released by the project periodically. Users will be notified of new data releases on the "What’s NEW" webpage on the MTBS website. 

I have found an MTBS dataset that has a problem. What do I do?

If you discover an issue with any of the MTBS geospatial datasets, please contact us. In the submitted email, please provide the name of the dataset and a short description of the problem. The MTBS project will evaluate the issue, make necessary corrections and repost the revised dataset to the MTBS project website.

How are MTBS geospatial data provided to users?

MTBS geospatial data are provided at two geographic levels: fire-level and state/national level. The suite of geospatial data compiled for each individually mapped MTBS fire (burn area boundary, continuous burn severity indices, thematic burn severity, etc.) are bundled as a fire-level dataset and provided as a single, compressed archived file. The compressed archive file for each completed MTBS fire can be located for download by using the MTBS Direct Download. 

Selected datasets from the suite of fire-level data are appended together by the MTBS project to create seamless national geospatial datasets. MTBS burn area boundary polygons are appended together as a single nationwide ESRI polygon shapefile with pertinent attributes. Additionally, fire occurrence point locations are calculated for each MTBS fire and compiled into a nationwide ESRI point shapefile. Thematic burn severity data for each individual MTBS fire are also mosaicked to generate annual, seamless burn severity GeoTiff images. All three of these national MTBS datasets can be downloaded from the MTBS Direct Download webpage.

How do I access MTBS geospatial data for a particular fire?

MTBS fires can be searched using the MTBS Direct Download. These tools allow users to create customized queries using one or more criteria to identify specific MTBS fires of interest. Fires meeting the user-designed query are listed with their associated geospatial datasets and mapping/visualization products that can be downloaded individually or in groupings.

I cannot identify a particular fire. Are all fires that meet the MTBS size thresholds mapped?

MTBS attempts to map all large fires based on the best available fire occurrence data and satellite imagery. However, due to one or more particular factors (i.e. erroneous reporting information, satellite imagery of poor quality, etc.), some fires cannot be mapped by the project.

What if I just want mapping products for MTBS fires and not the geospatial data?

In addition to the geospatial datasets, the MTBS project provides ready to use mapping and visualization products for each fire. These products include a letter-sized PDF map depicting the burn scar boundary superimposed on both a post-fire reflectance image and the thematic burn severity data. A location map, mapping summary and burn severity acreage summary are also included in the map product. A compressed Keyhole Markup Language (KML) is also provided for each MTBS fire that can be used in Google Earth. The KML consists of the pre/post fire Landsat image, burn area boundary, thematic burn severity data, and relevant fire mapping information. Both of these products are accessible for each fire using the MTBS Direct Download Tools.

What is the Monitoring Trends in Burn Severity (MTBS) project?

MTBS is an interagency program to map the location, extent and associated burn severity of all large fires (including wildfire, resource benefit fire and prescribed fire) in the United States across all ownerships from 1984 to present.

Why was the MTBS project implemented?

In 2004, the Wildland Fire Leadership Council adopted a strategy to monitor the effectiveness and effects of the National Fire Plan and the Healthy Forests Restoration Act (HFRA) initiated in 2000 and 2002, respectively. Module 2.1 of this strategy identifies the need to assess the environmental impacts of large wildland fires and identify trends in burn severity on all lands across the United States. This requires a consistent information base to synoptically assess environmental impacts and trends. Consequently, the MTBS program was implemented to generate and summarize burn severity information for this national analysis of trends in fire severity. Additionally, the project meets the recommendations outlined by a 2004 Government Accountability Office (GAO) report specifying the need for providing geospatial fire and burn severity characterization data at regional and sub-regional scales to support resource and risk assessments, resource management, monitoring, and research activities.

What is the Wildland Fire Leadership Council (WFLC)?

The Wildland Fire Leadership Council (WFLC) is a National level, interagency body with the responsibility to implement and coordinate the National Fire Plan (NFP) and other federal wildfire management policies. WFLC is the primary sponsor of the MTBS project.

Who is responsible for producing MTBS geospatial data and products?

The Monitoring Trends in Burn Severity program is jointly implemented by the U.S. Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS) and the U.S. Department of Agriculture Forest Service, Geospatial Technology and  Applications Center (GTAC). MTBS production work is divided between the two centers. Selected individuals from the Forest Service and DOI agencies, academia and NGOs provide technical consultation and support.

Who provides project funding for MTBS?

Funding support for the project is divided between the Forest Service and the Department of Interior.

How is MTBS related to LANDFIRE?

Starting in 2008, the LANDFIRE program began updating their existing vegetation and fuel layers to reflect landscape changes that had occurred since the nominal date (2001) of the baseline LANDFIRE dataset. MTBS provides LANDFIRE with a comprehensive and consistent source of fire disturbance and characterization data for fires that meet the MTBS size threshold. These data are used by LANDFIRE to update specific layers to reflect current conditions.

What is the difference between MTBS and BAER?

Similar to the MTBS project, Burned Area Emergency Response (BAER) Imagery Support is a cooperative effort between the USDA Forest Service Geospatial Technology and Applications Center and the USGS Earth Observation and Science Data Center. Through their combined efforts, the centers provide rapid response post-fire satellite imagery and emergency assessments of vegetation burn severity. A summary document describes the purpose and objectives of the BAER Imagery Support program and its relationship to the MTBS project.

Why does the MTBS data record begin in 1984?

MTBS leverages Landsat (TM/ETM+/OLI) satellite data for mapping and characterizing fires. Although the Landsat mission extends back to 1972, the first Thematic Mapper sensor was launched on Landsat 4 in 1982. Consequently, Landsat Thematic Mapper data continuity extends back to 1984.

Is there a publication that describes how MTBS data are compiled/processed?

Yes. Please see the 2007 publication entitled "A Project for Monitoring Trends in Burn Severity".

If you have a question which has not been addressed on the FAQs page, please contact us. Your question will be forwarded to the MTBS project and you will receive an answer. If appropriate, your question will be added to the MTBS FAQs web page.

What is Landsat?

Landsat is a series of Earth resource satellites jointly managed by NASA and the USGS. The first of eight Landsat missions was launched in 1972 with the latest launch occurring in 2013. Multispectral satellite imagery, collected by the Thematic Mapper (TM) sensor on board the Landsat 4 and 5 missions, the Enhanced Thematic Mapper (ETM+) sensor on board the Landsat 7 mission, and the Operational Land Imager (OLI) sensor on board the Landsat 8 mission, have been or are currently being used for mapping and characterizing MTBS fires. Additional technical information on Landsat is available from the NASA Landsat Program website and the USGS Landsat Missions website.

Why is Landsat used for mapping MTBS fires?

Landsat Thematic Mapper (TM), Landsat Enhanced Thematic Mapper (ETM+), and Landsat Operational Land Imager (OLI) data provide the longest consistent record of relatively high spatial and spectral resolution data for mapping fire severity. Landsat TM/ETM+/OLI data are also cost effective and are available for the entire temporal and geographic extent of the MTBS project.

I need help understanding MTBS data. Who can I contact?

For technical support regarding MTBS data or if you have a question about any other aspect of the MTBS project, please contact us.

I’m interested in using remote sensing for assessing fire effects and how MTBS utilizes this technology. How can I find out more information?

Technical guidance on Landsat-based remote sensing data processing and analysis, fire severity assessment strategies, and ground based measures of fire effects are documented as part of the Fire Effects Monitoring and Inventory System (FIREMON) in the FIREMON Landscape Assessment – Version 5 document. Additional publications and technical documentation on mapping and characterizing burn severity are provided on the MTBS Publications webpage.