There has been a rapidly increasing recent interest in how aboveground and belowground communities interact to drive ecosystem functioning. In this presentation I discuss how these interactions can help us to understand long term ecosystem change in forested ecosystems by focusing on three examples: (1) The impacts of invasive mammals in New Zealand rainforests; (2) The impacts of wildfire on lake islands in northern Sweden: and (3) Long term changes during ecosystem retrogression in contrasting forests around the world. All three examples point to the importance of linkages and feedbacks between the producer and decomposer subsystems in driving the fundamental characteristics of ecosystems in the long term perspective.