New Jersey is closing sections of five wildlife management areas that have become trouble spots for illegal swimming, partying and riding off-road vehicles, state environmental officials announced Friday. Beginning Wednesday, six relatively small patches of state-managed land will be off limits to everyone through Labor Day. Signs are being posted by the state Department of Environmental Protection warning people to keep out at the following locations: Cedar Lake Wildlife Management Area(Monroe Township, Gloucester County): The area commonly known as the Sand Plant, which begins at the interse…