Canadian Forest Service Publications
Ash regeneration capacity after emerald ash borer (EAB) outbreaks: Some early results. 2015. Aubin, I.; Cardou, F.; Ryall, K.; Kreutzweiser, D.; Scarr, T. Forestry Chronicle 91(3):291-298.
Issued by: Great Lakes Forestry Centre
Catalog ID: 36233
Availability: PDF (request by e-mail)
The emerald ash borer (EAB), a wood-boring beetle native of Asia, has killed millions of ash trees in North America since its detection in 2002. The rapid spread of the infestation and the widespread distribution and importance of ash in North America, coupled with the genus’ high vulnerability raise the crucial question of ash regeneration capacity following EAB infestation and its potentially broad ecological implications. We report on ash regeneration and infestation at the epicentre of the initial EAB invasion in Canada (near Windsor, Ontario). Up to 12 years after detection of the outbreak, we found abundant ash regeneration in the impacted area. However, the likelihood of these stems reaching maturity appears low. Dissection of a subsample of saplings allowed us to confirm the presence of an active residual EAB population, with infestation in 19% of regenerating stems (including stems as small as 2 cm in basal diameter). A vigorous regenerating ash cohort comprising a large portion of stump resprouts might allow for survival of the genus in the landscape for decades, but it is likely that the key functional role played by ash species will be definitively altered as a result of persistent EAB-caused mortality in maturing trees.
Plain Language Summary
This paper investigates the recovery potential of ash populations in areas heavily hit by the emerald ash borer (EAB). We surveyed sites formerly occupied by ash near the epicentre of the EAB outbreak in Canada (Essex County, Ontario). We censused both mature ash trees and new seedlings ten years after the first beetles were detected in the area. Our results show that very few mature ash survived the first wave of infestation, but that many young seedlings are present in the area. Nonetheless, when we actively looked for the beetle under the bark of these seedlings, we found that many of them were infested. In contrast with previous surveys, we found that resprouts from dead individuals represented an important proportion of new ash growth, suggesting that ash could potentially persist in the landscape as a low shrub with rapid regeneration/death cycles. When combined with knowledge of ash ecology, these results suggest that it is unlikely to maintain its important role within the ecosystem. This paper provides information on an important missing-link in our understanding of EAB effect on ash populations, and allows us to suggest practical management steps consistent with ash ecology.