Natural regeneration building urban forests, altering species composition

Terra Daily via SPX: 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."...

The southwest corner of Central Park in New York City, an HDR shot by Ed Yourdon, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license