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.
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 management.
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 during the same regional event.
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 monitoring to know that these events have even occurred.
Forests across northern Mississippi, Alabama and Georgia were hard hit by tornadoes in April, 2011. Tree mortality was often severe for areas in the direct path of these storms as shown in this photo from near Lake Burton in the Chattahoochee National Forest, Georgia (top). In this forest change map from June 1 (bottom), note the parallel, northeastern yellow-red streaks that reveal the location and intensity of these storms. Blue areas have similar growth as in 2010 and were unaffected. Black areas are non-forest such as fields or developed areas.