Beech bark disease does not reduce the long-term wood production of two forests contrasting in age, productivity, and structure

Abstract

The distribution of pests and pathogens is increasing in many forested regions, producing uncertainty for ecological functions, including aboveground wood net primary production (NPP). In North American deciduous forests, beech bark disease (BBD) is restructuring and modifying the composition of forest stands, producing gradients of Fagus grandifolia mortality at finer patch scales. We investigated the multi-decadal effects of BBD on the aboveground wood NPP of a moderately productive middle-successional stand positioned on a glacial outwash plain and a relatively high productivity late-successional stand located on a moraine. Despite average stand-scale basal area losses of ∼ 21% from BBD, aboveground wood NPP increased over time in both the middle- and late- successional stands. At the patch scale, the initial magnitude of change in aboveground wood NPP following BBD infestation correlated with the extent of recovery in the late, but not middle, successional stand, suggesting early responses to disturbance sometimes – but not always – predict long-term production patterns. Patch-scale aboveground wood NPP during different stages of BBD infestation was associated with vegetation quantity and production efficiency, with the latter generally increasing in later stages of the BBD progression. We conclude that the aboveground wood NPP of two forest stands increased through late stages of BBD, despite differences in stand productivity, structure, and age, while patch-scale aboveground wood NPP responses were more variable.