The effect of prescribed fire on Biscogniauxia infection and δ13C in an upland oak-pine forest

Abstract Incidents of Quercus decline have been driven by complicated interactions among factors, such as temperature, drought, pathogenic fungi, insect pests, and stand structure, which operate at multiple time scales. Past incidents of elevated tree mortality during drought in the upland forests of Oklahoma were associated with biotic factors; specifically, the infection of Quercus species by canker-causing fungi in the genus Biscogniauxia. Biscogniauxia canker and dieback have been previously associated with water stress but little is known about the interactions between forest densification, prescribed fire, water stress, and canker incidence. We investigated the effects of prescribed fire and reduced basal area on Biscogniauxia canker incidence in Quercus species at the Pushmataha Wildlife Management Area (PWMA) in southeastern Oklahoma. The PWMA is an ongoing forest management experiment established in 1984 with stands maintained to the present day with prescribed fire return intervals of 34+yr, 4-yr, and 1-yr. Through field surveys we found that the incidence of Biscogniauxia canker was lowest among units with a fire return interval of 1–4 years (p