ForWarn II

Satellite-Based Change Recognition and Tracking


Watching pine beetles in the Wasatch
02/03/2012 - 14:16

This image shows forest change anomalies on the north slope of the Wasatch Range of Utah on September 13, 2011 compared to the prior year. The high elevation zone above treeline is shown as an uncolored area under the words “Wasatch Range”. Most of the region’s forest is blue, meaning it is similar to that of 2010. Just below treeline, the Range’s slopes show a moderate to extreme departure in greenness. In recent years, the north slope in particular, has experienced repeated outbreaks of... (read more)

Forest loss marks strip mines
02/03/2012 - 14:14

Deforestation for strip mining is common practice in the coal regions of eastern Kentucky, Virginia and West Virginia. The image below shows areas where forests have been removed for mining over the last decade (left). Using a one-year baseline, it is possible to map areas that are both more and less vegetated on a shorter time scale. This maps where mining activity has been active, where succession or reclamation is taking place. The long term baseline reveals the cumulative effects of this... (read more)

Hurricane Irene makes landfall
02/03/2012 - 14:13

This before-after image pair shows changes associated with Hurricane Irene. Its path is shown by the bold blue line. In the pre-Irene image (left) shades of green and yellow show the effects of drought on vegetation and dark red spots are recent wildfires. Irene brought damaging winds that defoliated trees, but also much needed rain which increased greenness. By the end of September (right) the effects of the storm appear to have reduced vegetational vigor in the hardest hit areas of extreme... (read more)

Arizona bears the Wallow
02/03/2012 - 14:13

In June, the Wallow Fire burned over half a million acres in east-central Arizona, much of it on the Apache-Sitgreaves National Forests. A substantial portion of the burn area was of high severity, killing millions of trees outright. Looking south-southwest over the Escudilla Mountain Fire Lookout Tower (upper left), the effects of the high severity fire are clear. This observed severity is consistent with the ForWarn map from July (upper right, shown with 50 percent transparency) that... (read more)

Rapid regrowth as the Okefenokee burns
02/03/2012 - 14:11

Georgia’s Okefenokee Swamp National Wildlife Refuge near the Georgia-Florida line burned in 2007 and again in 2011. This rapid recovery of fuels reflects the importance of sprouting vegetation. In the map sequence from the summer of 2011, this resilience is clear. By June 17, wildfire had spread northward through about half the Refuge as shown in red (left). By July 19 (center), fire had progressed north and a new fire became evident northwest of the Refuge. By August 20 (right), vegetation... (read more)

Monitoring a Pocosin fire and its recovery
02/03/2012 - 14:10

The Pains Bay Fire was started by lightning on May 4, 2011 in the peaty soils of North Carolina’s coastal plain. By the end of June, the fire was contained, but the deep soils continued to smolder for weeks. The white line marks this 45,000 acre fire’s final perimeter. The center of the fire burned with low severity, allowing rapid recovery of herbs, ferns and sprouting woody species by August; yet an outer ring shows a longer lasting departure from prior years. For more information about... (read more)

Tornado tears through Massachusetts
02/03/2012 - 14:09

A severe tornado touched down near Springfield, Massachusetts on June 1, 2011, then carved a path through nearly 30 miles of state and private forest. The streak in red show an extreme reduction in growth compared to the prior year’s condition as of mid-June. Many of the trees damaged or destroyed were evergreen conifers that recover slowly. Always remember that many disturbed areas are salvaged after the event, so the ultimate change can involve both the disturbance and subsequent forest... (read more)

Caterpillars defoliate the Pee Dee
02/03/2012 - 14:08

According to climate data, coastal North and South Carolina were having a mild drought in mid May of 2011. Mean water flow for the Pee Dee River near Pee Dee, SC during the 24-days prior to May 16 was 15.9% below the 2003-2010 average for that time according to USGS statistics ( These clues suggest that this reduction along the Waccama and Pee Dee Rivers of the Carolinas is not the result of flooding. Aerial detection... (read more)

The Great Smoky Mountains tornado
02/03/2012 - 14:07

The April 27, 2011 tornado that hit Great Smoky Mountains National Park in eastern Tennessee was a powerful EF4 storm (its direction is indicated by the black arrow). Wind storms are important natural disturbances for Southern Appalachian forests, and the ecological impacts of this event will be long-lasting as shown in the inset photograph taken by National Park staff soon after the event. Also note the forest disturbance northwest of Maryville. That was the result of strong wind and hail... (read more)

Tracking the ephemeral in Tennessee
02/03/2012 - 14:06

Full-fledged tornadoes are typically well documented, but the massive outbreak of April 2011 also had localized short-term effects that are easily overlooked. This image pair from a month after the storm (top) and two months later (bottom) shows how fast seemingly severe damage can recover, in this case a ridgeline forest southwest of Kingsport, Tennessee. While such ephemeral disturbances from wind and hail can reduce tree productivity and annual growth, it takes high frequency forest... (read more)