Regionally Averaged Diameter Growth in New England Forests

📖 The Scoop

A regional sample of tree-ring measurements was used to determine average annual growth in trees of 10 major species in New England. There have been extended periods of decreasing growth rates in red spruce since about 1960 and in balsam fir since about 1965. The other eight species, which included sugar maple and white pine, showed constant or increasing growth rates through 1980. The decreases in growth rate in sampled red spruce and balsam fir were independent of physical site characteristics, elevation, and geographic location, indicating that regional factors are involved. Weather parameters and indexes were not closely correlated with growth rates, and the best predictive equation explained only 33 percent of annual variation. Due to past harvests and epidemics of the spruce budworm, much of the red spruce-balsam fir forest below 1,000 m in elevation can be considered to be functioning as even-aged. Historical growth information suggests that these trees should have reached maximum growth around 1960, and that decreasing growth rates since then are the result of normal aging.

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