NCRS - The Changing Midwest Assessment

Percent Change in Oak Decline, 1980 - 2000

Oak decline, as the name implies, is a condition that leads to oak mortality. There is no single cause of oak decline, although it is generally thought to be the result of damage associated with insects, diseases, and severe weather - especially drought. Older oak trees - especially red oaks - seem to be the most susceptible to oak decline.

Oak decline is not a new phenomenon; however, it is of special concern because of the dramatic increase in the number of acres affected in the forests just to the south of the North Central Region. For example, the number of "severely affected" acres in Arkansas increased from 19,000 in 1999 to an estimated 300,000 in 2001. The Oak/Hickory Forest Type Group is the most prevalent in the North Central Region - accounting for no less than 28 percent of all forest over the past 20 years - and it is of great economic, ecological, and social value to wildlife and people.

This slide show consists of a series of county and state level maps that depict changes in oak decline in oak dominated portions of the North Central Region, including counties with at least 30,000 acres of forestland, at least 10% of which is within the Oak/Hickory Forest Type Group, over the past approximately 20 years. Oak decline was evaluated using Forest Inventory and Analysis individual tree data from two cycles of data collection from each state in the Region - an early cycle and a late cycle, approximately represented by the dates 1980 and 2000. All living oak stems that were at least one inch in diameter at breast height and that occurred on field plots that contained at least 25 percent oak were included. Plots were visited during the growing season.