MONTPELIER -- Red spruce trees in New England and upstate New York suffered severe damage last winter, University of Vermont researchers have found. The scientists have not determined the cause of the damage but say a number of factors, including acid rain, may have weakened the trees.
In a widespread study at 28 sites in Vermont, New Hampshire, Massachusetts, and New York, more than half of the trees lost foliage and some lost buds.
''In 2003, an average of 46 percent of current-year spruce foliage was killed at our study sites, and injury was about 65 percent for the largest forest trees," said UVM researcher Brynne Lazarus. ''What was worse was that many buds were also killed."
The research was published in the September issue of the Canadian Journal of Forest Research. Red spruce are most common in higher elevations and there also are stands at lower elevations in the northeast corner of Vermont.
The damage, marked by red needles and sparse branches, was the most widespread since 1989, scientists said.
The injuries were worse in trees at higher elevations and on western slopes of mountains, said Paul Schaberg, a plant physiologist with the US Forest Service.
''It's the same kind of pattern that we see for acid rain in the area," said Schaberg.
In the 1970s and early '80s, some of the region's mountaintops were scarred by dying trees from acid rain, which is rainwater polluted by sulfur emissions from Midwest power plants and other sources.
Since that time, the red spruce had looked healthier, indicating to scientists that the most vulnerable trees had died off and were replaced with stronger trees, Schaberg said. That theory made last year's damage puzzling.
UVM researchers first noticed the damage while skiing and hiking at higher elevations.
A lack of nutrients in the soil may have contributed to the damage. Acid deposits in soil from acid rain tend to deplete calcium in soil, Lazarus said.