2018-19 Rapid Ag: Minnesota's rural Forests and the Expanding Emerald Ash Borer - Landscape Risks and Forest Management Response
Department of Forest Resources and UMN Extension
- 2018 Fiscal Year: $93,876
The emerald ash borer (Agrilus planipennis; EAB) was recently observed in northern Minnesota, with two confirmations in the city of Duluth in 2016. In December 2016, an area of northeastern Carlton County was proposed for quarantine, joining 13 other counties located in northeastern Minnesota, the Twin Cities metro, and southeastern Minnesota. The expansion of EAB to Minnesota’s northern forests has led managers to seek information on alternative forest management scenarios to maintain the health and productivity of ash forests across the state.
There is often significant lag time between EAB establishment and human detection1. This lag time coupled with the finding that annual ash mortality increases by as much as 2.7% annually after EAB is first observed in a county2 highlight how little is known about the economic risks and management strategies to combat EAB across Minnesota’s forests. In Minnesota, three species of ash serve as hosts to EAB: black (Fraxinus nigra), green (Fraxinus pennsylvanica), and white ash (Fraxinus americana).
Black ash alone ranks sixth as the most common tree across the state, representing over a million cubic feet of timber volume on forestland3. Black ash fills an important niche in Minnesota’s forests, occurring on and dominating very wet sites which few other species can survive on. This lack of diversity puts black ash forest types at high risk of transitioning from forest cover to shrub cover. Even with concerted effort, reforestation of these sites after EAB will be extremely difficult since black ash trees are important for controlling hydrology, and some sites will “swamp out” after ash loss4.
Statewide forest inventory records indicate ash trees are located on approximately 28% of all inventory plots across Minnesota. Across the state, EAB could cause up to 1.8 million cords of mortality annually in rural areas5.
Despite the impacts that EAB can have on ash timber supplies and the health of Minnesota’s rural forests, landscape-level risks and assessments of management strategies currently being conducted by state, county, and tribal forest managers have not been compiled across the state’s diverse ash forests. Developing an understanding of the geographic distribution of the ash resource can inform conservation practices and landscape-level response frameworks that seek to proactively maintain biodiversity of forest ecosystems. Mapping ash in Minnesota will be crucial to rapid response efforts by anticipating where EAB infestations will occur.
The overall goal of this project is to use remote sensing technologies to predict ash occurrence and relative abundance across Minnesota and to synthesize current management efforts in ash-dominated forests across the state. Specific objectives are to:
- Map ash tree occurrence and abundance (relative basal area) at a 30-m resolution across Minnesota.
- Document and assess effectiveness of current restoration efforts being conducted by forest managers in ash-dominated forests on lands where EAB is anticipated to have an impact.
- Siegert, N.W., McCullough, D.G., Liebhold, A.M., Telewski, F.W. 2007. Resurrected from the ashes: a historical reconstruction of emerald ash borer dynamics through dendrochronological analyses. Proc. 2006 Emerald Ash Borer Res. Technol. Dev. Meet. ed. V. Mastro, D. Lance, R. Reardon, G. Parra, pp. 18–19.
- Morin, R.S., Liebhold, A.M., Pugh, S.A., Crocker, S.J., In press. Regional assessment of emerald ash borer, Agrilus planipennis, impacts in forests of the eastern United States. Biological Invasions.
- Miles, P.D., VanderSchaaf, C.L., 2015. Forests of Minnesota, 2014. Resource Update FS-44. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 4 pp.
- Slesak, R.A., Lenhart, C.F., Brooks, K.N., D’Amato, A.W., Palik, B.J. 2014. Water table response to harvesting and simulated emerald ash borer mortality in black ash wetlands in Minnesota, USA. Canadian Journal of Forest Research 44: 961-968.
- Minnesota Department of Natural Resources, 2011. Estimated impacts of emerald ash borer (EAB) on ash timber supply in Minnesota. 25 pp.