Wildland fire emissions, carbon, and climate: Seeing the forest and the trees – A cross-scale assessment of wildfire and carbon dynamics in fire-prone, forested ecosystems

Wildfires are an important component of the terrestrial carbon cycle and one of the main pathways for movement of carbon from the land surface to the atmosphere. Fires have received much attention in recent years as potential catalysts for shifting landscapes from carbon sinks to carbon sources. Unless structural or functional ecosystem shifts occur, net carbon balance in fire-adapted systems at steady state is zero when assessed over the entire post-fire successional sequence and at landscape scales. When evaluated at fine spatial scales and over short periods of time, however, wildfires may seem to release more carbon to the atmosphere than remains on site. Measurements of wildfire carbon emissions are thus highly biased by the spatial and temporal scales that bound them, and may over- or under-estimate carbon source-sink dynamics that provide critical feedbacks to the climate system. This synthesis paper provides a description of the ecological drivers of wildfires and carbon in forested ecosystems across the spatial and temporal scales at which system drivers (e.g., climate, weather), behaviors (e.g., wildfire occurrence, spread, intensity), and resulting patterns (e.g., vegetation composition and structure, carbon emissions) occur and interact. Improved understanding of these relationships is critical if we are to anticipate and respond to major changes in the global earth system expected in the coming decades and centuries