New Harvard Forest Publication: Presence of HWA reduces hemlock regeneration

New results by Forest Ecologist Dave Orwig and others show that hemlock stands invaded by the hemlock woolly adelgid (HWA) experience dramatic reductions in regeneration of new hemlock seedlings, making the insect's destruction difficult to reverse. In extensive surveys of 141 hemlock stands in southern New England, hemlock seedling density declined 71% between 2007 and 2009, while HWA infestation continued to increase (91% of the study areas were infested by 2009). In addition, recent sampling highlights that a second invasive pest, the elongate hemlock scale, was also widespread, occurring in 87% of the stands. According to the new paper in the Canadian Journal of Forest Research, HWA threatens to permanently alter native ecosystems where hemlock provides critical wildlife habitat while shading and cooling headwater streams. Read "Eastern hemlock regeneration in the presence of hemlock woolly adelgid and elongate hemlock scale."