New Publication: Hemlock Woolly Adelgid Distribution and Impact in Central MA

A recent paper by David Orwig, Jonathan Thompson, David Foster, and several former Summer Research Program students discusses the factors influencing the spread of the invasive hemlock woolly adelgid (HWA) in central New England hemlock forests. 

Using aerial photographs, they investigated over 86,000 hectares (more than 200,000 acres) of hemlock forest in Central Mass. and subsampled 123 stands to examine the distribution of HWA and its impact on tree vigor and mortality since its arrival in the region in 1989. 

Latitude and winter climate variables most strongly impacted HWA density. Contrary to predictions, there was no regional increase in pre-emptive hemlock harvesting. Cold temperatures appear to be slowing the spread and impact of HWA at its northern extent; HWA infestation intensity and hemlock mortality and vigor were strongly linked to average minimum winter temperature. 

Read the full Ecosphere paper: A foundation tree at the precipice: Tsuga canadensis health after the arrival of Adelges tsugae in central New England.