Patterns of Coarse Woody Debris in Hardwood Forests across a Chronosequence of Ash Mortality Due to the Emerald Ash Borer (Agrilus planipennis)

Abstract

ABSTRACT: The invasive emerald ash borer (Agrilus planipennis) (EAB) is causing widespread ash (Fraxinus spp.) mortality in 25 U.S. states and two Canadian provinces. We investigated the impact of EAB on coarse woody debris (CWD) volume across 24 sites in western and central Ohio, USA, representing a chronosequence of ash mortality, quantified by the year ash mortality reached 25% (Year25%Dead). CWD volume averaged 60.36 m3/ha, and was positively associated with total (live plus dead) ash basal area (BA), but was not greater in sites where ash death occurred earlier. For the volume of CWD in the first, least-rotted, decay class, stepwise regression revealed that both ash BA and Year25%Dead were significant predictors; sites with more ash BA and where ash mortality had occurred earlier had more class 1 CWD. Additionally, class 1 CWD in those early mortality sites was primarily (87%) ash, compared to 40% ash in sites with more recent ash mortality. This large influx of CWD, particularly ash CWD, combined wi...