The nonprofit Washington Parks & People has spent a quarter century creating and improving green spaces as a way to challenge the cycle of poverty and violence in blighted urban areas. But the clock is ticking on the last six months of the organization’s stimulus grant, which funds Green Corps, a program that trains long-term unemployed D.C. residents to be urban foresters and mentors them through the job search process. City of Trees profiles three employees, each struggling against a history of missed opportunities, as they begin to transform their lives by transforming landscapes. As conflicts erupt between D.C. Ward 8 residents and Green Corps workers, the director of Parks & People must learn from his employees how to manage touchy issues of stewardship and collaborate with a population skeptical of outside interventions.  LB