Using forest service forest inventory and analysis data to estimate regional oak decline and oak mortality

Damage and mortality data are collected as part of the US Forest Service, Forest Inventory and Analysis (FIA) ongoing assessments of the nation's timberlands. The usefulness and value of FIA tree data in assessing historical levels of oak decline and oak mortality were investigated for seven Midwestern states. The data were collected during two periodic inventories conducted between the early 1970s and the mid-1990s. One-tenth to one-third of the oak trees had decline-associated damage in a given inventory, but no trends over time were apparent across the states. The percentages of dead trees ranged from less than I to I I across all inventories and states; mortality was higher in the late inventory than the early inventory for all states. This is the first reported attempt to quantify oak decline across the Midwestern Region and it was accomplished using FIA tree data. The major concerns of the approach used are the subjective nature of the damage codes used to tabulate declining oaks and the inconsistencies and inherent subjectivities in the FIA recorded codes. The major drawback for non-FIA researchers is the time required to understand the intricacies of the FIA system.