NASA eyes declining vegetation in the eastern United States from 2000 to 2010

NASA: NASA scientists report that warmer temperatures and changes in precipitation locally and regionally have altered the growth of large forest areas in the eastern United States over the past 10 years. Using NASA’s Terra satellite, scientists examined the relationship between natural plant growth trends, as monitored by NASA satellite images, and variations in climate over the eastern United States from 2000 to 2010.

Monthly satellite images from the MODerate resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) showed declining density of the green forest cover during summer in four sub-regions, the Upper Great Lakes, southern Appalachian, mid-Atlantic, and southeastern Coastal Plain. More than 20 percent of the non-agricultural area in the four sub-regions that showed decline during the growing season, were covered by forests. Nearly 40 percent of the forested area within the mid-Atlantic sub-region alone showed a significant decline in forest canopy cover.

“We looked next at the relationships between warmer temperatures, rainfall patterns, and reduced forest greenness across these regions,” said Christopher Potter, a research scientist at NASA’s Ames Research Center, Moffett Field, Calif. “This comprehensive data set gave us the evidence to conclude that a series of relatively dry years since 2000 has been unfavorable for vigorous growth of forest cover over much of the eastern U. S. this past decade.” Potter is the first author of the paper titled “Declining Vegetation Growth Rates in the Eastern United States from 2000 to 2010,” published by Natural Resources, Dec. 2012, (3), 184-190.

...More recent studies indicate that climate change could be having many adverse and interrelated impacts on the region. The warming climate this century has caused new stresses on trees, such as insect pest outbreaks and the introduction of new pathogens. Scientists consider both climate change and disease to be dominant driving forces in the health of forests in this region....

Trends in forest canopy green cover over the eastern United States from 2000 to 2010 derived from NASA MODIS satellite sensor data. Green shades indicate a positive trend of increasing growing season green cover, whereas brown shades indicate a negative trend of decreasing growing season green cover. Four forest sub-regions of interest are outlined in red, north to south as: Great Lakes, Southern Appalachian, Mid-Atlantic, and southeastern Coastal Plain. Image credit: NASA