Fire exclusion, pyrogenic carbon, and ecosystem function: What have we lost?

Abstract

Settler colonialism and active fire exclusion greatly eliminated recurrent fire from forests and grasslands in the United States. Pyrogenic carbon (PyC), a key legacy of fire and a stable form of carbon (C) in soils, has inadvertently been lost with the cessation of biomass burning. Using a simple simulation, we estimate that fire exclusion from grasslands over the last 125 years has resulted in a loss of 963–1,028 Tg of PyC, approximately equivalent to a 12% - 22% decline in the soil PyC reservoir. This loss of PyC from grassland ecosystems and the lack of introduction of fresh PyC has likely had a significant impact on soil health in the Great Plains. To rebuild this lost stable C pool and the associated ecosystem function of PyC, we recommend combining Indigenous Knowledge and western science to restore historical fire regimes to forests and grasslands and reintroduce PyC via biochar application to agricultural fields.