NCRS - The Changing Midwest Assessment

Although the death of a tree is a natural part of the life cycle of a forest, we monitor the rate and causes of mortality as indicators of overall forest health. In the North Central Region we are currently keeping a close eye on oak mortality because of the increase in oak decline in the forests of the southern United States. Oak decline, a condition that leads to mortality, is the result of damage associated with a combination of many factors acting over several years, including insects, diseases and severe weather - especially drought. See the Oak Decline slide show for more information on this condition.

This slide show consists of a series of maps that depict changes in oak mortality over the past approximately 20 years. Maps depict oak mortality in counties with at least 30,000 acres of forestland, at least 10% of which is within the Oak/Hickory Forest Type Group. Oak mortality was evaluated using Forest Inventory and Analysis individual tree data from two cycles of data collection in each state in the Region - an early cycle and a late cycle, approximately represented by the dates 1980 and 2000. All oak stems that were at least eleven inches in diameter at breast height (sawtimber-size) and that occurred on field plots that contained at least 25 percent oak were included.