Time Since Last Disturbance

The metric for time since disturbance ("tsd") was measured as time in years before 2021 since the most recent disturbance of at least 25% canopy cover loss per 30m pixel as defined by eDaRT Mortality Magnitude Index (MMI) layers. MMI values less than 25% were not considered.

The most recent disturbance class ("dist_class") of the most recent disturbance of 25% magnitude or greater detected by eDaRT and were prioritized in the order: fire (1), treatment (2), eDaRT (3). For example, if a pixel intersected a fire perimeter and a treatment polygon, that pixel would be assigned a code of 1 (fire) rather than 2 (treatment). Note that while the occurrence of and magnitude of a disturbance was determined using eDaRT, disturbance class was determined first using fire perimeters and FACTS activities, with remaining eDaRT disturbances collectively assigned to insect- and disease-related tree mortality. This data layer currently exists only for the Sierra Nevada region.

Data and Resources

Additional Info

Field Value
Version Version 5.0
Last Updated March 28, 2025, 08:35 (UTC)
Created March 7, 2025, 07:52 (UTC)
category /Forest and Shrubland Resilience/Disturbance
collection_name California Landscape Metrics
creation_method Layers representing time since disturbance, most recent disturbance magnitude, and most recent disturbance class were produced using the Ecosystem Disturbance and Recovery Tracker (eDaRT), Forest Activities ([FACTS](https://data.fs.usda.gov/nrm/briefingpapers/FACTS.pdf)) and CAL FIRE Timber Harvesting Plan ([THP](https://www.fire.ca.gov/programs/resource-management/forest-practice/timber-harvesting/timber-harvesting-plan-thp/)) databases, and the CAL FIRE Fire and Resource Assessment Program ([FRAP](https://frap.fire.ca.gov/mapping/gis-data/)) fire perimeter dataset. All layers are complete for the entire area within the 300s and 400s eDaRT scenes as well as for scenes 103, 105, and 501. The reference year was set to 2021 since fire history and eDaRT only reported up through 2020. The earliest year assessed was 2010 since eDaRT data prior to 2010 was used for model training and is not reliable.
data_units Years
data_vintage 2021
date_updated August 2024
element Disturbance
encoding utf8
file_name SNV_TimeSinceLastDisturb_2021_202209_T2_v5
format GeoTiff
harvest_object_id 7ccee013-b93b-4121-8d41-0aaaeb0d31fa
harvest_source_id a2637971-af12-457f-ae4a-831d2202a539
harvest_source_title WIFIRE Commons
metric_definition_and_relevance The metric for time since disturbance ("tsd") was measured as time in years before 2021 since the most recent disturbance of at least 25% canopy cover loss per 30m pixel as defined by eDaRT Mortality Magnitude Index (MMI) layers. MMI values less than 25% were not considered. The most recent disturbance class ("dist_class") of the most recent disturbance of 25% magnitude or greater detected by eDaRT and were prioritized in the order: fire (1), treatment (2), eDaRT (3). For example, if a pixel intersected a fire perimeter and a treatment polygon, that pixel would be assigned a code of 1 (fire) rather than 2 (treatment). Note that while the occurrence of and magnitude of a disturbance was determined using eDaRT, disturbance class was determined first using fire perimeters and FACTS activities, with remaining eDaRT disturbances collectively assigned to insect- and disease-related tree mortality. This data layer currently exists only for the Sierra Nevada region.
pillar Forest and Shrubland Resilience
spatial {"type": "Polygon", "coordinates": [[[-122.2883616476824, 35.05769372687348], [-117.5563290826801, 35.05769372687348], [-117.5563290826801, 42.00332292672577], [-122.2883616476824, 42.00332292672577], [-122.2883616476824, 35.05769372687348]]]}
tier 2