Dynamics of coarse woody debris in emerald ash borer -infested forest stands

Downed coarse woody debris (DCWD) in forests plays an important role in ecological processes such as in nutrient (e.g., water, carbon, and nitrogen) cycling, plant regeneration and growth, and habitat for forest fauna. Large-scale tree mortality is a key factor contributing to DCWD. We are assessing the spatial and temporal patterns of DCWD in southeastern Michigan and western Ohio forests resulting from widespread ash mortality caused by emerald ash borer (Agrilus planipennis) (EAB). In Michigan, during the last 3-4 years more than 85% of ash trees have died and are converting to DCWD. Specific objectives include quantifying: 1) the volume and species of DCWD; 2) rate of input of DCWD as a function of EAB-induced ash mortality and ash species; and 3) the volume and species of non-ash trees felled by falling ash snags. In 2008, thirty stands containing black (Fraxinus nigra), green (F. pennsylvanica), and white (F. americana) ash were sampled on hydric, mesic, and xeric sites, respectively. In Michigan, these stands represent a gradient of decreasing ash mortality (22-45 Km) from the epicenter of the EAB invasion. For all DCWD we quantified volume (m³/ha), decay class, tree species, direction of tree fall (degrees), manner of tree fall (uprooted or broken), as well as size of the stump and root-mass. Overall, our results will provide information about the short-term changes in DCWD due to a major disturbance agent, thus, contributing to an increased understanding of cascading ecological impacts of an invasive forest insect.