SYRACUSE, N.Y., August 21, 2012 In forested regions of the nation, natural regeneration may help cities achieve tree cover goals at the expense of maintaining the desired tree species.
A study by U.S. Forest Service scientists published recently in Urban Forestry and Urban Greening showed that on average, 1 in 3 trees in sampled cities were planted while two-thirds resulted from natural regeneration. However, for newly established, young trees in cities in forested regions, only about 1 in 12 trees (Syracuse, N.Y.) to 1 in 20 trees (Baltimore) were planted. The lower proportion of naturally regenerated trees in the entire city tree population may be because naturally regenerated trees have a higher mortality rate than planted trees, according to Dave Nowak, a research forester with the Forest Service's Northern Research Station and the study's principal investigator. Naturally regenerated trees typically have more competition for the water, light and nutrients that are needed for survival.
"Urban forests change constantly in response to human activities and environmental factors," said Michael T. Rains, Director of the Northern Research Station. "This study is an example of the work U.S. Forest Service scientists are doing to help cities and counties achieve healthy and sustainable urban forests."
Most of the cities included in the study are located within forested regions, where environmental conditions favor trees. The study suggests that natural regeneration may be the most cost-effective means to attain desired tree cover levels and associated ecosystem services in forested regions, but relying on natural regeneration may alter the tree species making up a given forest.
The study included Baltimore, Chicago, Hartford, Conn., Los Angeles and Syracuse, N.Y., as well as nine cities in the Canadian province of Ontario.
The percentage of planted trees within the entire tree population ranged from a low of 11.1 percent in Hartford t
|Contact: Jane Hodgins|
USDA Forest Service - Northern Research Station