Wednesday, August 6, 2008

PS 45-105: A living laboratory at Dempsey Wetlands: Forest ecology and emerald ash borer (Agrilus planipennis) research by middle school students

Kathleen S. Knight1, Joanne Rebbeck1, Deborah A. Bogard2, and Kamal Gandhi3. (1) US Forest Service Northern Research Station, (2) Delaware City Schools, (3) Ohio State University


Through a collaborative effort between US Forest Service scientists and a middle school teacher, 7th and 8th grade advanced science students established monitoring plots and collected ecological data at the Dempsey Wetlands, a 15 ha school forest including mature forest, old fields, and various successional stages.  The project was motivated by the discovery of emerald ash borer (EAB) (Agrilus planipennis) in an adjacent private woodlot.  EAB is expected to cause 100% mortality of ash (Fraxinus spp.) trees in infested areas.  Students began in fall 2006 by tagging, identifying, and measuring the DBH (diameter at 1.4 m height) of trees in 60 78 m2 plots on transects through the mature forest and along trails in the early successional areas.  Students used a dichotomous winter key that we developed, which includes only tree species, or species groups, commonly found in the school forest.  To examine EAB ecology, during winter and spring 2008, one ash tree from each plot in the early successional areas was felled and the trunk was cut into 1 m segments.  Students examined the outside of the segments for woodpecker feeding, EAB exit holes, and exit holes of other insects, then peeled away the bark to reveal EAB and native insect galleries.  EAB and non-EAB insects were preserved for later identification. 


The mature forest is dominated by hickory (Carya spp.), oak (Quercus spp.), and elm (Ulmus spp.), while the early successional areas are dominated by ash, elm, and black cherry (Prunus serotina).  Both green ash (F. pennsylvanica) and white ash (F. americana) are present, with ash trees comprising 10% of the mature forest trees and 23% of the early successional area trees.  Infestation was patchy, with some trees heavily infested, some trees lightly infested, and others completely uninfested.  EAB galleries were most common from the ground to 5m height.  This may be due to preferences for larger diameter portions of the trunk, which only occur low on these small trees.  Very few EAB larvae were found in trunk segments <5 cm diameter.  Native insects were more common in trees infested by EAB.  2-year development of EAB larvae was observed.  Woodpeckers consumed up to 90% of EAB larvae in the trees, with an average of approximately 30% of the larvae consumed per tree.  Woodpeckers preferred to feed higher on the trunk in lightly infested trees, however, in heavily infested trees, woodpeckers fed on all segments of the trunk.