Mikhail Beketov's supporters said the verdict was just another sign of the degradation of media freedom in Russia.
Another journalist covering the same story was beaten so badly over the weekend that doctors placed him into an artificial coma in an effort to protect his brain.
Mr Beketov, a reporter for the Khimkinskaya Pravda newspaper, irked authorities with his articles about corruption involving the Khimki forest, part of which officials have torn down to make way for a highway to St Petersburg.
He now uses a wheelchair and is unable to speak after a vicious beating by two unidentified assailants near his home left him unconscious in the snow and forced doctors to amputate his leg. His supporters claim the attack was retaliation for articles criticising local authorities.
One of the officials Mr Beketov criticised was Vladimir Strelchenko, the mayor of Khimki, a town just outside Moscow that is home to the forest.
Mr Beketov gave a 2007 interview in which he accused Mr Strelchenko of being involved in blowing up his car.
Mr Strelchenko sued for slander, and the court in Khimki issued a $160 fine yesterday but said that Mr Beketov did not have to pay because of a technicality.
Mr Beketov's assistant said he would appeal.
The scandal over the road was also a chief topic in the writings of Oleg Kashin, a reporter for the respected Kommersant newspaper who was brutally attacked on Saturday in Moscow.