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Mapping causes of disturbance in U.S. forests

Date: June 18, 2020


Forests are constantly changing. To monitor forest health and manage these lands for multiple uses, managers need to understand the processes driving forest change at fine spatial scales over long time spans, because different processes have different impacts on social, economic, and ecological systems.

A collaborative project between the USFS Forest Inventory and Analysis Program (FIA), NASA, and several universities has developed a national dataset mapping the location, timing, and cause of canopy loss events due to removals, fire, stress, wind, and land use conversion, as well as unperturbed forest areas across the conterminous United States from 1986-2010.

A map of the United States showing forest loss event types - green (most of the northeast and west) shows stable forest, purple (most of the southeast) shows removal, and other colors indicate fire, stress, conversion, wind, and other.
Forest canopy loss event types in the contiguous United States,1986–2010.

The North American Forest Dynamics (NAFD) project is a core project of the North American Carbon Program (NACP). It was designed to use observations from Landsat satellites to clarify the events and processes resulting in forest loss and improve understanding of the carbon budget for the conterminous United States (Goward et al., 2008).  

A six-panel graph - each panel shows an event type, with year on the x axis and area affected on the y axis.
Forest area (km2) affected annually by event type, stacked and color filled by FIA region. A second y-axis on the right labels the area as a percentage of total CONUS forestland. From Schleeweis et al. 2020.

This study used Landsat imagery and a set of algorithms to link forest change event type and timing to more than 258 million hectares of U.S. forested ecosystems. The resulting maps show areas of persisting forest cover loss resulting from land use conversion, as well as temporary losses caused by fire, removals, stress, and wind. 

Over 24 years of data, 1986-2010, we find most forest area (71 percent) experienced little to no canopy cover loss. Where canopy cover loss was detected, the vast majority was attributed to temporary removals (81 percent), with only a very small fraction attributed to land use change. This improved characterization of forest cover loss will help support analysis not previously possible across the entire conterminous United States.

Key Findings

  • Of the 258 million hectares of forest mapped across the conterminous United States between 1986 and 2010, 75.95 million hectares experienced detectable canopy cover loss with 81 percent attributed to removals, 12 percent to wildfire, 5 percent to stress, and 2 percent to conversion.
  • Through time, within and between geographic regions, the relative area per year of removals, fire, and stress varied substantially.
  • A synthesis focusing on temporal and spatial scales, relevant processes, and ecological depth of available datasets suggests knowledge gaps remain.

 

A multi-panel image with one map of FS lands and fire boundaries, one of forest change type, one of forest change year, and maps of confidence and dominance. They show that the model predicts change due to fire in the time and place that fire occurred.

 

Featured Publications

Schleeweis, Karen ; Moisen, Gretchen ; Schroeder, Todd A. ; Toney, Chris ; Freeman, Elizabeth ; Goward, Samuel N. ; Huang, Chengquan ; Dungan, Jennifer L. , 2020
Zhao, Feng ; Huang, Chengquan ; Goward, Samuel N. ; Schleeweis, Karen ; Rishmawi, Khaldoun ; Lindsey, Mary A. ; Denning, Elaine ; Keddell, Louis ; Cohen, Warren B. ; Yang, Zhiqiang ; Dungan, Jennifer L. ; Michaelis, Andrew , 2018
Schroeder, Todd A. ; Schleeweis, Karen ; Moisen, Gretchen ; Toney, Chris ; Cohen, Warren B. ; Freeman, Elizabeth ; Yang, Zhiqiang ; Huang, Chengquan , 2017
Cohen, Warren B. ; Yang, Zhiqiang ; Stehman, Stephen V ; Schroeder, Todd A. ; Bell, David M. ; Masek, Jeffrey G. ; Huang, Chengquan ; Meigs, Garrett W. , 2016
Schleeweis, Karen ; Goward, Samuel N. ; Huang, Chengquan ; Dwyer, John L. ; Dungan, Jennifer L. ; Lindsey, Mary A. ; Michaelis, Andrew ; Rishmawi, Khaldoun ; Masek, Jeffery G. , 2016


Principal Investigators: 
Forest Service Partners: 
Todd A. Schroeder, Southern Research Station FIA
Chris Toney, RMRS (technician)
Elizabeth A. Freeman, RMRS (technician)
External Partners: 
Samuel N. Goward, UMD
Chengquan Huang, UMD
Jennifer L. Dugan (NASA Ames)