Over the next 18 months, landscape contractors will replace 3,400 trees lost to development in recent decades in Norristown and four other municipalities in the Philadelphia suburbs.

The $2.2 million effort is intended to help manage storm-water runoff, revitalize neighborhoods, and improve air and water quality, according to the Pennsylvania Horticultural Society, a partner in the project with the Delaware Valley Regional Planning Commission.

Warminster and New Hope, in Bucks County, and Chester and Millbourne, in Delaware County, will also receive trees. They will be placed along streets, near government buildings and schools, in parks, and, in one case, at a historic cemetery on the border of Norristown and West Norriton, said Maitreyi Roy, a horticultural society vice president. The trees will be matched to their surroundings — hickory trees will go in Norristown Farm Park, for example.

Contractors will do the planting because the young trees are much too large for novices to handle. The contractors will tend the trees for two years, until they are established.

The funding is coming from the Pennsylvania Infrastructure and Investment Authority, a state agency that supports a variety of projects. The municipalities were chosen because they have large streams and rivers, and combined sewers that can overflow. Trees reduce the amount of runoff and overflow, said Todd Baylson, who is helping manage the project for the horticultural society.

David Forrest, Norristown's municipal administrator, said he was "thrilled" by the news that the borough would get 2,000 trees. In recent years, 500 have been planted through other projects, and this initiative builds on that effort, he said.

"For me, the places where the trees are going to make the most dramatic difference are the streets," Forrest said. "They are going to help with the physical revitalization of the community. Where a block now seems barren, the trees will make it softer and more inviting."

That will encourage people to fix up their neighborhood, and it's going to change the perception of the neighborhoods in Norristown."

Contact Bonnie L. Cook at 610-313-8232 or bcook@phillynews.com. Read her blog "MontCo Memo," at www.philly.com.