Conservation of ash diversity: Strategies for preserving diversity and population structures of ash invaded by emerald ash borer

Wide-scale mortality of ash trees by emerald ash borer (Agrilus planipennis, EAB) threatens the Fraxinus genus with regional extirpation, creating the need for strategies to conserve the ash gene pool.  In such an attempt, the Five River MetroParks (FRMP) in Dayton, OH initiated an ongoing program to protect 600 mature ash trees with insecticide in 2011.  The goal of our study is to evaluate the effect of this conservation program on genetic diversity and ash population dynamics.  Preliminary assessments of the ash population at FRMP were performed to evaluate composition of ash species, importance, and canopy thinning (rating scale 1-5; 1 for healthy ash with no signs of EAB to 5 for dead trees) within 1 ha stands.  Sugar maple (Acer saccharum) is the most common tree species (23.8%), but total ash composition was 42.3% (for 5 species) suggesting that ash is an important forest tree at FRMP.  Five ash species (white ash, F. americana; green ash, F. pennsylvanica, black ash, F. nigra, pumpkin ash, F. profunda, and blue ash, F. quadrangulata) are found at FRMP.  All ash species exhibit signs of EAB infestation, ranging from canopy thinning of =2.2 ± 0.12 in blue ash to =3.3 ± 0.10 in white and green ash.  Our data shows that ash is an important tree species and EAB densities are present at FRMP.  Further evaluations will continue to measure population dynamics and genetic diversity of ash age cohorts and compare FRMP to both an uninfested area (New York) and areas that have undergone high rates EAB-induced ash mortality (southeast Michigan).