Global Forest Disturbance Alert System

The Global Forest Disturbance Alert System (GloF-DAS) provides data on forest disturbance globally on a quarterly basis. [news release]

Reliable maps of global forest cover change are frequently years out-of-date. Consequently, there is a pressing need to develop techniques for monitoring and verifying land cover change and forest disturbances in a timely, low-cost, and accurate manner. Satellite remote sensing from instruments such as NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) offers a consistent and cost-effective method for mapping forest cover change. MODIS data are obtained freely with global daily cover products.

A new MODIS product called the "Quarterly Indicator of Cover Change" (QUICC) has been developed at NASA Ames Research Center by the CASA ecosystem modeling team. The QUICC product is based on comparison of MODIS global vegetation index images at the exact same time period each year (ending of March, June, September, and December) in consecutive years. The CASA team updates its global QUICC products as soon as the newest quarterly MODIS worldwide VI image at 5-km spatial resolution is available.

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• Forest disturbance locations are shown as center points of 5 km x 5 km areas that were detected with a significant loss of forest greenness cover (greater than 40%) over the previous 12 months. [see example]
• The cause(s) of any forest disturbance point detected in this map has yet to be confirmed.
• Disturbance locations and impacts are subject to verification through local observations.
• Due to atmospheric interference with satellite image quality, the providers of this forest disturbance data set can make no global assurances of its accuracy.
• For more information on development of these forest disturbance products, visit geo.arc.nasa.gov/sge/casa/latest.html.
• NASA Ames Research Center offers forest carbon sequestration predictions throughout the world at CQUEST. The NASA Carbon Query and Evaluation Support Tools (CQUEST) viewer application allows users to display CASA forest carbon fluxes and stocks interactively as a map, customize the view, query data values, extract areas of interest and print and download image files. CQUEST is a free decision support tools that will help users determine their baseline levels of forest carbon sequestration for project planning anywhere in the world.

+ FAQs >>

CURRENT PUBLICATIONS
Potter, C. S., 2014, Global Assessment of Damage to Coastal Ecosystem Vegetation from Tropical Storms, Remote Sensing Letters, (in press). There is also comprehensive validation results using US wildfire perimeters presented on our website link.

PREVIOUS REFERENCES
We have published papers on similar land cover change detection methods and can cite:
• Potter, C., P. Tan, V. Kumar, C. Kucharik, S. Klooster, V. Genovese, W. Cohen, and S. Healey, 2005, Recent history of large-scale ecosystem disturbances in North America derived from the AVHRR satellite record, Ecosystems, 8(7), 808.
• Potter, C., V. Kumar, S. Klooster, and R. Nemani, 2007, Recent history of trends in vegetation greenness and large-scale ecosystem disturbances in Eurasia, Tellus B, 59, 260-272.

ACCURACY ASSESSMENT
Our newest QUICC product is in beta test phase. We note however that, due to atmospheric interference with satellite image quality, we can make no global assurances of its accuracy. QUICC is an early alert product for forest cover change, making timeliness the highest priority for users to identify possible new areas of deforestation and degradation. The accuracy assessment that is most important will come in the future from users who visit tropical forest locations and report back to us on the causes and consequences of forest cover change.

WEATHER EVENTS
El Nino/La Nina events may not be detected at our greenness change threshold in rainforest areas, but since severe drought can lead to forest fire, such weather cycles could be legitimate causal agents of forest change and should not be filtered out.

HIGH-RESOLUTION IMAGE COMPARISON
The underlying imagery is generally older than the MODIS-based QUICC change points, so high-resolution imagery in internet map services may not reflect the current state of the forest cover.

CHANGE DETECTION THRESHOLD
QUICC registers a probable change in forests when canopy green cover has decreased by at least 40 percent within 5x5 square kilometer area over the previous 12 months.

SEASONALITY
Seasonal variation in forest canopy cover is mitigated through the QUICC product's quarterly baseline.

+ Feedback >>

GloF-DAS is a collaborative research project. We are therefore interested in information from users on the most probable causes of any given forest disturbance point. If you have information, please contact us

Alternatively if you have suggestions on how to improve GloF-DAS, please contact us.

+ Alert system >>

In coming months, GloF-DAS will offer an alert system whereby users can sign up to get notifications via email or SMS text message on recent changes in forest cover for a specified location or country.

GloF-DAS is done in partnership with Cal State Monterey Bay and NASA Ames Research Center.



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