While property owners struggle to protect their hemlock trees from the invasion of the hemlock wooly adelgid, research now shows the pest is killing trees more quickly than expected.
The research came from the U.S. Forest Service Southern Research Station (SRS) in Otto, N.C. The research also suggests the rapid death of the hemlocks is altering the carbon cycle of the forests.
The research was published recently in the journal Ecosystems.
According to the report, Eastern hemlock, a keystone species in the streamside forests of the Southern Appalachian region, already is experiencing widespread decline and mortality because of hemlock woolly adelgid (a tiny nonnative insect) infestation.
A keystone species is an organism with a major influence in its ecosystem. The Eastern hemlock "plays an important role in the ecology and hydrology of mountain ecosystems. Hemlock forests provide critical habitat for birds and other animals; their shade helps maintain the cool water temperatures required by trout and other aquatic organisms in mountain streams," the report states.
The wooly adelgid is considered to have the potential to kill most of the region's hemlock trees within the next decade.
Coweeta scientists compared rates of decline of adelgid-infested hemlock trees to a small number of girdled trees that were not infested. Girdling is stripping bark from a tree to stop water and nutrient flow from roots to the crown.
After tracking changes over a three-year period the scientists were surprised to discover adelgid-infested trees declined as quickly as girdled trees.
The study appears to support "the widely-held belief that adelgid-infested hemlock trees in the South are declining much faster than the reported nine-year decline of some infested hemlock trees in the Northeast."
The study suggests infrequent frigid winter temperatures in the South may not be enough to suppress adelgid populations, leading to hemlocks dying faster and the infestation spreading.
While hemlocks are dying, scientists have not determined yet what tree species will replace them.The Northeast Georgian
