Early changes in physical tree characteristics during an oak decline event in the Ozark highlandsThis article is part of a larger document. View the larger document here.
An oak decline event is severely affecting up to 120 000 ha in the Ozark National Forest of Arkansas. Results of early changes in physical tree characteristics during that event are presented. In the fall and winter of 1999 and 2000, we established research plots on a site that would become a center of severe oak decline. In August 2000, standing trees > 14 cm in diameter at breast height on twenty-four 0.3025-ha plots were inventoried. By late summer 2001, oak decline symptoms were evident. In November 2001, overstory trees on six plots were remeasured and changes in physical tree characteristics between the inventories were compared. Standing dead trees (all species < 35 cm in diameter at breast height) increased from 52 to 70 trees/ha (p = 0.049). The number of northern red oak (Quercus rubra L.) trees exhibiting epicormic branching increased from 9 trees/ha in 2000 to 55 trees/ha in 2001 (p = 0.009). Evidence of red oak borer damage on that portion of the main stem extending through the tree crown increased from 2 trees/ha in 2000 to 31 trees/ha in 2001 (p = 0.008). The mean ratio of standing dead to live trees increased from 0.15 in 2000 to 0.25 by 2001. I term this ratio the "forest health quotient." In 2000 the quotient was already above expected values, evidence of its potential utility in early detection of forest health issues.