Recent changes in the montane spruce-fir forests of the northeastern United States.

Intensive study of the montane spruce-fir forests of the northeastern United States has been underway since 1980. Crown-vigor assessments, tree-ring studies, and resurveys of plots established in the 1960's have revealed a deterioration of the red spruce populations at high elevations in New England and New York. Forested sites surveyed in the 1960's and 1980's have shown decreases in density and basal area of greater than 50%. Many of these sites have not been logged or cut since settlement times and it is not expected for red spruce, a long-lived species, to undergo such a rapid, widespread decline in basal area and density. The most prominent feature of red spruce decline in the high-elevation forests of the Northeast is the loss of foliage from the tops of the crown down and from the tips of lateral branches in. Winter injury is responsible for this pattern of needle loss and, in some years, browning of needles occurs in early spring and is followed by needle loss by mid-summer. Reports from the 1800's and earlier this century describe a similar occurrence of needle browning but the previous extent and severity of this phenomenon is not known. Climate including adverse winter conditions are in part responsible for the current red spruce decline. The role of air pollution in red spruce decline has not been determined. Foliar nutrient deficiencies may exist in some high-elevation red spruce and their role in red spruce decline is not known either.