Hey-spread out! City Forestry Commission, concerned that trees planted too closely have to compete, calls for wider spacing; Oak Park, IL

Oak Park gives tree more space to grow -- chicagotribune.com:
Stately trees with lush green canopies arching over village streets are a common sight in Oak Park.

But the proximity of the trees to each other may be damaging to their health, according to the village forester, voicing a concern echoed in other suburban communities.

So Oak Park's Village Board has voted to widen the minimum planting distance between new trees to 50 feet from 35 feet.

The move comes as the village is losing about 400 trees a year to various diseases and age. Dutch elm disease claimed about 200 trees this year, and the emerald ash borer is starting to claim others. In addition, many of the lush Norway maples are starting to succumb to old age.