THE BRONX - Most Bronx residents walk on them every day: sidewalks that are buckled, cracked and uneven because of tree roots. City Councilman James Vacca (D-The Bronx) says the city's Department of Parks and Recreation is responsible for root pruning on city property, but says the agency has fallen far behind. On Morris Park Avenue, a salon owner says the unstable sidewalk in front of her shop recently caused a pregnant woman to trip. She says she's worried someone will get seriously hurt if nothing is done.