Bassist Orion Miller plays Heartwood in SF Symphony's Soundbox: "Urban Forests." | Credit: Brandon Patoc In the San Francisco Symphony’s second SoundBox program of the year, the concert begins well before the music, as curator Gabriella Smith collapses the boundary between performance and environment. The Berkeley-born composer is known for weaving the natural world into her music, but in her two-night engagement of “Urban Forest,” she takes that mission a step further.