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Rapid Recovery of Gross Production and Respiration in a Mesic Mountain Big Sagebrush Ecosystem Following Prescribed Fire

Fellows, Aaron W., Flerchinger, Gerald N., Lohse, Kathleen A., Seyfried, Mark S.
Ecosystems 2018 v.21 no.7 pp. 1283-1294
Artemisia tridentata, aboveground biomass, basins, biomass production, carbon, carbon cycle, carbon sinks, ecosystems, forbs, grasses, leaf area index, net ecosystem production, prescribed burning, shrubs, uncertainty, Western United States
The impact of land management actions such as prescribed fire remains a key uncertainty in understanding the spatiotemporal patterns of carbon cycling in the Western USA. We therefore quantified carbon exchange and aboveground carbon stocks following a prescribed fire in a mountain big sagebrush ecosystem located in the northern Great Basin, USA. Specifically, we examined the changes in plant functional type, leaf area index, standing aboveground carbon stocks, net ecosystem production (NEP), gross ecosystem production (GEP), and ecosystem-level respiration (Rₑcₒ) for 2 years before and 7 of 9 years after a prescribed fire. Post-burn GEP and Rₑcₒ exceeded pre-burn GEP and Rₑcₒ within 2 years and remained elevated. The variation in GEP and Rₑcₒ provided no evidence of a large and prolonged net efflux of carbon in the 9 years after the fire. Rather, NEP indicated the site was a sink before and after the fire, with little change in sink strength associated with the burn. Re-sprouting and recruitment of grasses and forbs drove the post-burn increase in GEP. Woody shrub growth was the dominant control on aboveground biomass accumulation after fire, with shrub aboveground biomass reaching ~ 11% of pre-burn biomass after 5 years. The rapid recovery of GEP and the growth of mid-successional shrubs suggest ecosystem-level carbon fluxes and stocks can recover rapidly after fire in mesic mountain big sagebrush ecosystems.