ForWarn II

Satellite-Based Change Recognition and Tracking


Defoliation on the bayou
03/15/2012 - 19:20

Spring often brings defoliating insects to the forests of Louisiana. In this image from early May 2010, defoliations from forest tent caterpillars and baldcypress leafrollers create an erupting "measles-like" pattern. Note the subtle differences in severity outward from the centers of several of the blotches. The insets show the baldcypress leafroller (left: photo by Gerald Lenhard, LSU: 0014219) and the forest tent caterpillar (right; photo by Stephen Katovich, USFS; (read more)

Lake-effect snow affects spring greenup
03/15/2012 - 16:11

This late April 2010 image shows a large anomaly just east of Lake Ontario on the Tug Hill Plateau of New York. A less severe area of departure from the prior year’s condition occurs to the east. Based on weather records, the 2009-10 winter at Lake Pleasant, just east of Tug Hill, was 4.5 degrees F warmer than it was during the prior winter. Continued warmth into spring explains why so much of the northeast is strongly blue in this image. Somewhat ironically, warmer winter temperatures... (read more)

A rare outbreak of pine butterflies
02/24/2012 - 10:20

Outbreaks of the defoliating pine butterfly are rare. In eastern Oregon, outbreaks occurred in 1908-11, 1940-43, 1982 and from 2008 to 2011. Sometimes defoliations can lead to mass mortality of ponderosa pine—the primary host, but not always. This current outbreak on the Malheur National Forest is largely responsible for the forest change anomalies in ForWarn for September 29, 2011 compared to 2010. According to aerial detection surveys, areas inside and outside these pine butterfly areas... (read more)

High water soaks the Atchafalaya
02/03/2012 - 14:22

The Atchafalaya basin's forests thrive with seasonal flooding, yet high water is normally a spring phenomenon there. During the past month, unusually high water levels have inundated wetlands and forests along and near the Mississippi River basin. From space, floodwaters appear to decrease existing vegetation, as water masks low lying plant cover. According to the USGS, river discharge at Morgan City, Louisiana was 145,000 ft3/sec on January 16, 2012 compared to 84,000 ft3/sec the prior year... (read more)

Drought takes a toll on Texas trees
02/03/2012 - 14:21

The forests of Texas continue to suffer through one of the most extreme droughts on record and a large number of trees have already died. The photo shows mortality in Memorial Park, Houston (Ron Billings, Texas Forest Service). By late August of 2011, the regional change in greenness from the prior year were extreme. Across the map, this decline was caused by the combined effects of drought and fire. By December of 2011, some recovery occurred as shown in blue, but this December condition... (read more)

Webworms erupt in the Allegheny
02/03/2012 - 14:21

This fall 2011 webworm outbreak in the Hickory Creek Wilderness Area of the Allegheny National Forest, Pennsylvania stands out against the near normal (blue) background that dominated the state in early fall. There were minimal indications of defoliation in mid-August, but clear patterns of severity were clear by mid-September. This anomaly persisted through November, when leaflessness is the normal pre-winter condition for deciduous trees. Recognizing insect defoliations near the end of the... (read more)

Fire and frost hit the Upper Midwest
02/03/2012 - 14:20

In September of 2011, the Pagami Creek Fire burned over 92,000 acres in the Boundary Waters Canoe Area Wilderness (BWCAW) of the Superior National Forest, Minnesota Much of this burned at high severity, as indicated on the October forest change image. This was the largest fire to occur in this area since the 1999 blowdown event. The less extreme forest change shown in yellow and orange across northern Wisconsin and Michigan is largely the result of a hard early frost that accelerated the... (read more)

Defoliation in the Wenatchee
02/03/2012 - 14:19

A sizable portion of the Wenatchee National Forest, Washington shows less vegetational vigor than it did at its peak of the last decade. While such declines in NDVI often result from tree death due to wildfires in the west, no large fire has occurred here as is shown by the distribution of MODIS hotspots (shown as white triangles) between 2000 and 2011. Much of this reduction through September 13, 2011 may have been caused by the cumulative effects of defoliating insects on tree mortality,... (read more)

Development cuts forests near Raleigh
02/03/2012 - 14:18

Substantial forest area has fallen to development in the periphery of many urban areas over the last decade. The image below shows deforestation in the periphery of Raleigh, NC as yellow to red anomalies. Blue areas have not changed during the last decade. This reveals that many forested inliers have been converted south and east of downtown, but that large areas have been converted west of the city along the outer highway belt. The large block of unroaded blue northwest of downtown is a... (read more)

Yazoo tornado recovery
02/03/2012 - 14:16

On April 24, 2010, a lethal F4 tornado struck the forests east of Yazoo City, Mississippi. Within a few weeks the path of the storm and patterns of severity are clearly shown with this comparison of conditions relative to the same time in 2010--the year before the event (top image). After one year of recovery, that same track is shown in dark blue compared to the post-disturbance 1-year baseline. Had the long-term baseline been used for 2011, the path would still be shown as anomalously low... (read more)