Sequoia National Park encompasses over 400,000 acres across the Sierra Nevada mountains. The park’s giant old growth sequoias are the largest trees in the world, growing 30 feet (9.1 m) in diameter and 250 feet (76.2 m) tall over their 3,000-year lifespans.
The park was established in 1890 to protect the giant sequoias from logging, which was the main threat to sequoia groves in the 19th and 20th centuries. A new threat to the park’s giant sequoias has emerged in the 21st century in the form of more intense and frequent wildfires.
Fires have always been a part of the giant sequoia ecosystem. Thick bark and high branches have helped protect the trees from mortality during fires. Low intensity fires actually help sequoias reproduce. The heat boosts the release of sequoia cone seeds, which then take root in the open spaces created by wildfires. More frequent, higher intensity fires in recent years, however, now threaten the Sequoias. The Castle Fire, for example, started on August 19, 2020 and burned until January 5, 2021, charring more than 170,000 acres and devasting the giant sequoia population within Sequoia National Forest and the surrounding area. A preliminary assessment by the National Park Service (NPS) estimated that the Castle Fire killed 10-14% of sequoias in the Sierra Nevadas, an estimated 7,500 to 10,600 trees.
The recently released Land Change Monitoring, Assessment, and Projection (LCMAP) Collection 1.2 annual land cover and land surface change products from a U.S. Geological Survey initiative can help scientists understand the impact of such fires. LCMAP leverages the historical Landsat archive to fit the Continuous Change Detection and Classification (CCDC) algorithm, which is used both to classify land cover and to identify land surface changes over the United States from 1985 to the most recent calendar year. The unprecedented historical time series, combined with annual updates, help scientists examine pre-fire landscape dynamics, provide recent information concerning land change events, and contribute to understanding post-fire recovery in the affected areas.
False color imagery created from nonvisible and visible energy available from Landsat Analysis Ready Data (ARD) records (Figure 2) show the progression of the Castle Fire from August 20, 2020, to November 24, 2020, in the animation below. The image from August 20 shows the region before the fire began. By August 27, Landsat ARD shows the Castle Fire beginning inside the Sequoia National Forest but still outside of the national park. Green represents vegetation, active fires appear orange, and the burn scar shows up as a reddish-brown color. The fire gradually progresses west and south in early September before turning north towards Sequoia National Park in late September, breaching the national park’s borders in October. By November 24, a snowfall (cyan) inside the national park helped put the fire out.
LCMAP’s Time of Spectral Change (SCTIME) product shows the approximate date a spectral change was detected, based on the point in time at which spectral observations diverged from CCDC model predictions. Figure 3 shows the monthly progression of the fire in 2020.
Another LCMAP product, the Spectral Stability Period (SCSTAB), represents the number of days the CCDC time series model has remained unchanged. SCSTAB from July 1, 2020, just prior to the fire, shows most areas burned in the Castle Fire had been stable for over 36 years (figure 4).
LCMAP products can be combined with Landsat Analysis Ready Data (ARD) and other Earth Resources Observation and Science (EROS) Center land cover products for enhanced insights into recent land change events. The Landscape Fire and Resource Management Planning Tools (LANDFIRE) program is a partnership between the U.S. Department of Interior, the U.S. Department of Agriculture Forest Service and The Nature Conservancy. LANDFIRE provides over 20 geospatial vegetation-related products that cover the entire United States and helps scientists comprehend and model wildfire behavior across diverse landscapes. LANDFIRE uses disturbance and seasonal reflectance data derived from Landsat along with species, cover, and height plot data from the LANDFIRE Reference Database, and nationally calibrated fuels information along with numerous other datasets, such as 3DEP Lidar, the National Land Cover Database (NLCD), and the National Agriculture Statistics Service cropland data layer to provide crucial geospatial data on vegetation, wildland fuel, and fire regimes. Figure 5 shows the existing vegetation height (EVH) LANDFIRE product, which represents the average tree height of the dominant and co-dominant trees and the percent cover weighted height of herbaceous and shrub vegetation. EVH shows herbaceous, shrub, and tree height within the region prior to the Castle Fire for each pixel.
The existing vegetation cover (EVC) displayed in figure 6 is a product that shows the percent of the herbaceous, shrub, and tree canopy for the dominant lifeform. The combination of LCMAP data and LANDFIRE EVH and EVC products can help scientists comprehend and inventory the damage caused by the Castle Fire and assess vegetation losses.
The LCMAP time series gives researchers the ability to track changes on the landscape for recent and historical land cover change events, including wildfires. Annual updates to the LCMAP time series allow researchers to understand post-disturbance recovery of the landscape. Combined with other products, we can gain even greater insights into what was lost (in terms of forest inventory) during these tragic events and how they shape and change the landscape.
References
National Park Service contributors, 2021, The Largest Trees in the World: National Park Service, accessed December 3, 2021, at https://www.nps.gov/seki/learn/nature/largest-trees-in-world.htm
National Park Service contributors, 2021, Wildfires Kill Unprecedented Numbers of Large Sequoia Trees: National Park Service, accessed December 3, 2021, at https://www.nps.gov/articles/000/wildfires-kill-unprecedented-numbers-of-large-sequoia-trees.htm
U.S. Forest Service contributors, 2021, SQF Complex: U.S. Forest Service, accessed December 3, 2021, at https://data.rgj.com/fires/incident/7048/castle-fire/
Stephenson, N., and Brigham, C., 2021, Preliminary Estimates of Sequoia Mortality in the 2020 Castle Fire: National Park Service, accessed December 3, 2021, at https://www.nps.gov/articles/000/preliminary-estimates-of-sequoia-mortality-in-the-2020-castle-fire.htm
U.S. Department of Interior contributors, 2017, 11 Things You Didn’t Know about Sequoia and Kings Canyon National Parks: U.S. Department of Interior, accessed December 3, 2021, at https://www.doi.gov/blog/11-things-you-didnt-know-about-sequoia-and-kings-canyon-national-parks
Material written by:
Charles Robison 1 and Cole Krehbiel 1
1KBR, Inc. contractor to the U.S. Geological Survey, Earth Resources Observation and Science (EROS) Center, Sioux Falls, South Dakota, USA. Work performed under USGS contract 140G0121D0001.
- Overview
Sequoia National Park encompasses over 400,000 acres across the Sierra Nevada mountains. The park’s giant old growth sequoias are the largest trees in the world, growing 30 feet (9.1 m) in diameter and 250 feet (76.2 m) tall over their 3,000-year lifespans.
The park was established in 1890 to protect the giant sequoias from logging, which was the main threat to sequoia groves in the 19th and 20th centuries. A new threat to the park’s giant sequoias has emerged in the 21st century in the form of more intense and frequent wildfires.
Sources/Usage: Public Domain.Figure 1 - The location of Sequoia National Park and the Castle Fire boundary in the southern Sierra Nevada in central California, within the conterminous United States. Fires have always been a part of the giant sequoia ecosystem. Thick bark and high branches have helped protect the trees from mortality during fires. Low intensity fires actually help sequoias reproduce. The heat boosts the release of sequoia cone seeds, which then take root in the open spaces created by wildfires. More frequent, higher intensity fires in recent years, however, now threaten the Sequoias. The Castle Fire, for example, started on August 19, 2020 and burned until January 5, 2021, charring more than 170,000 acres and devasting the giant sequoia population within Sequoia National Forest and the surrounding area. A preliminary assessment by the National Park Service (NPS) estimated that the Castle Fire killed 10-14% of sequoias in the Sierra Nevadas, an estimated 7,500 to 10,600 trees.
The recently released Land Change Monitoring, Assessment, and Projection (LCMAP) Collection 1.2 annual land cover and land surface change products from a U.S. Geological Survey initiative can help scientists understand the impact of such fires. LCMAP leverages the historical Landsat archive to fit the Continuous Change Detection and Classification (CCDC) algorithm, which is used both to classify land cover and to identify land surface changes over the United States from 1985 to the most recent calendar year. The unprecedented historical time series, combined with annual updates, help scientists examine pre-fire landscape dynamics, provide recent information concerning land change events, and contribute to understanding post-fire recovery in the affected areas.
False color imagery created from nonvisible and visible energy available from Landsat Analysis Ready Data (ARD) records (Figure 2) show the progression of the Castle Fire from August 20, 2020, to November 24, 2020, in the animation below. The image from August 20 shows the region before the fire began. By August 27, Landsat ARD shows the Castle Fire beginning inside the Sequoia National Forest but still outside of the national park. Green represents vegetation, active fires appear orange, and the burn scar shows up as a reddish-brown color. The fire gradually progresses west and south in early September before turning north towards Sequoia National Park in late September, breaching the national park’s borders in October. By November 24, a snowfall (cyan) inside the national park helped put the fire out.
Sources/Usage: Public Domain.Figure 2 - A time series of Landsat Analysis Read Data (ARD) false color composites using short-wave infrared, near infrared, and red bands (Bands 7, 5, 4) acquired from August to November 2020 over the Castle (SQF Complex) Fire in California. Vegetation is shown in shades of green, active fire appears orange, and the subsequent burn scar shows as a reddish-brown color. LCMAP’s Time of Spectral Change (SCTIME) product shows the approximate date a spectral change was detected, based on the point in time at which spectral observations diverged from CCDC model predictions. Figure 3 shows the monthly progression of the fire in 2020.
Sources/Usage: Public Domain.Figure 3 - The Collection 1.2 Land Change Monitoring, Assessment, and Projection (LCMAP) Time of Spectral Change (SCTIME) product shows the timing of a spectral change within 2020, defined as a “break” in the Continuous Change Detection and Classification (CCDC) time series model where daily estimates of spectral observations diverged from model predictions, shown by month. Notice both the Landsat ARD time series and SCTIME image show the progression of the fire from August (green) spreading north into Sequoia National Park by the end of September (purple). Another LCMAP product, the Spectral Stability Period (SCSTAB), represents the number of days the CCDC time series model has remained unchanged. SCSTAB from July 1, 2020, just prior to the fire, shows most areas burned in the Castle Fire had been stable for over 36 years (figure 4).
Sources/Usage: Public Domain.Figure 4 - The Collection 1.2 LCMAP Spectral Stability Period (SCSTAB) product represents the length, in days, of the time series model in effect as of July 1st of 2020. Note that most of the areas burned in the fire had been stable for the entirety of the LCMAP time period, which now covers 36 years of data. This is not surprising, as parts of this area includes groves of Sequoia trees, some of which have been around for thousands of years. A study by the National Park Service suggests that 10 – 14% of large sequoias in the Sierra Nevada may have been killed in the 2020 Castle Fire. LCMAP products can be combined with Landsat Analysis Ready Data (ARD) and other Earth Resources Observation and Science (EROS) Center land cover products for enhanced insights into recent land change events. The Landscape Fire and Resource Management Planning Tools (LANDFIRE) program is a partnership between the U.S. Department of Interior, the U.S. Department of Agriculture Forest Service and The Nature Conservancy. LANDFIRE provides over 20 geospatial vegetation-related products that cover the entire United States and helps scientists comprehend and model wildfire behavior across diverse landscapes. LANDFIRE uses disturbance and seasonal reflectance data derived from Landsat along with species, cover, and height plot data from the LANDFIRE Reference Database, and nationally calibrated fuels information along with numerous other datasets, such as 3DEP Lidar, the National Land Cover Database (NLCD), and the National Agriculture Statistics Service cropland data layer to provide crucial geospatial data on vegetation, wildland fuel, and fire regimes. Figure 5 shows the existing vegetation height (EVH) LANDFIRE product, which represents the average tree height of the dominant and co-dominant trees and the percent cover weighted height of herbaceous and shrub vegetation. EVH shows herbaceous, shrub, and tree height within the region prior to the Castle Fire for each pixel.
Sources/Usage: Public Domain.Figure 5 - The Landscape Fire and Resource Management Planning Tools (LANDFIRE) existing vegetation height (EVH) product represents the average height of the dominant vegetation for the year 2016. Note the tree height of the Castle Fire area that burned in September and October mainly consisted of giant sequoias with average heights up to 127.9 feet (39 meters) shown in dark green. The existing vegetation cover (EVC) displayed in figure 6 is a product that shows the percent of the herbaceous, shrub, and tree canopy for the dominant lifeform. The combination of LCMAP data and LANDFIRE EVH and EVC products can help scientists comprehend and inventory the damage caused by the Castle Fire and assess vegetation losses.
Sources/Usage: Public Domain.Figure 6 - The Landscape Fire and Resource Management Planning Tools (LANDFIRE) existing vegetation cover (EVC) product describes the percent cover of the live canopy and includes tree, shrub, and herbaceous cover types. Note the overlapping areas of the Castle fire and Sequoia National Park in the northwest part of the map that show dense canopies of large growth sequoias and lighter green areas that show less dense areas of sequoias that were burned during the Castle Fire. The LCMAP time series gives researchers the ability to track changes on the landscape for recent and historical land cover change events, including wildfires. Annual updates to the LCMAP time series allow researchers to understand post-disturbance recovery of the landscape. Combined with other products, we can gain even greater insights into what was lost (in terms of forest inventory) during these tragic events and how they shape and change the landscape.
References
National Park Service contributors, 2021, The Largest Trees in the World: National Park Service, accessed December 3, 2021, at https://www.nps.gov/seki/learn/nature/largest-trees-in-world.htm
National Park Service contributors, 2021, Wildfires Kill Unprecedented Numbers of Large Sequoia Trees: National Park Service, accessed December 3, 2021, at https://www.nps.gov/articles/000/wildfires-kill-unprecedented-numbers-of-large-sequoia-trees.htm
U.S. Forest Service contributors, 2021, SQF Complex: U.S. Forest Service, accessed December 3, 2021, at https://data.rgj.com/fires/incident/7048/castle-fire/
Stephenson, N., and Brigham, C., 2021, Preliminary Estimates of Sequoia Mortality in the 2020 Castle Fire: National Park Service, accessed December 3, 2021, at https://www.nps.gov/articles/000/preliminary-estimates-of-sequoia-mortality-in-the-2020-castle-fire.htm
U.S. Department of Interior contributors, 2017, 11 Things You Didn’t Know about Sequoia and Kings Canyon National Parks: U.S. Department of Interior, accessed December 3, 2021, at https://www.doi.gov/blog/11-things-you-didnt-know-about-sequoia-and-kings-canyon-national-parks
Material written by:
Charles Robison 1 and Cole Krehbiel 1
1KBR, Inc. contractor to the U.S. Geological Survey, Earth Resources Observation and Science (EROS) Center, Sioux Falls, South Dakota, USA. Work performed under USGS contract 140G0121D0001.