Emerald ash borer (EAB) (Agrilus planipennis) has had an extensive impact across North America. It is currently present in Minnesota, USA but has not been observed in northern portions of the state where the vast majority of black ash (Fraxinus nigra) trees are located. Unlike other ash forest communities, the black ash forest type occurs in wetlands and is dominated by black ash with few associate species. Because of this, the loss of black ash can result in changes to the hydrological regime and species composition. The goal of this study was to quantify the structure and composition of regeneration 5 to 11 years post-harvest in three silvicultural systems (group selection, clearcut, and diameter-limit harvesting) to evaluate the potential for establishment of other tree species. Overall, regeneration post-harvest was high but variable across all systems. Across silvicultural systems, there was no significant relationships between residual overstory trees (> 10 cm dbh) basal area and non-ash regeneration TPH, indicating flexibility in designing treatments for diversification. Populus sapling (2.54–10 cm) density was significantly negatively correlated to the depth of the soil muck layer. In contrast, a positive relationship was observed between depth of the soil muck and black ash saplings. These findings indicate that specific silvicultural systems in combination with site quality (e.g., clearcuts on high-quality sites with shallow muck layers) may help to promote non-ash species in black ash forests that are threatened with EAB.
Bibliographical noteFunding Information:
This work was supported by the Minnesota Agricultural Experiment Station-Rapid Agricultural Response Fund and projects MN 42-063 and 42- 068. Acknowledgements
The authors are grateful for the multiple land management organizations which supplied silvicultural prescription information and allowed sampling of sites including the Minnesota Department of Natural Resources, Aitkin County, Carlton County, Lake County, and St. Louis County. Field data were collected by Grace Ditch, Trevor Host, and Brian Anderson.
© 2020, Springer Nature B.V.
- Diameter-limit harvest
- Group selection