From pools to flow: The PROMISE framework for new insights on soil carbon cycling in a changing world. (16th October 2020)

• Record Type: Journal Article
• Authors: Waring, Bonnie G.; Sulman, Benjamin N.; Reed, Sasha; Smith, A. Peyton; Averill, Colin; Creamer, Courtney A.; Cusack, Daniela F.; Hall, Steven J.; Jastrow, Julie D.; Jilling, Andrea; Kemner, Kenneth M.; Kleber, Markus; Liu, Xiao‐Jun Allen; Pett‐Ridge, Jennifer; Schulz, Marjorie
• Is Part Of: Global change biology. Volume 26:Number 12(2020)
• Page Start: 6631
• Page End: 6643
• Publication Date: 2020-10-16
• Subjects: biogeochemical model -- organic matter -- organo‐mineral interactions -- pore structure -- soil carbon -- soil microbes; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.15365
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Soils represent the largest terrestrial reservoir of organic carbon, and the balance between soil organic carbon (SOC) formation and loss will drive powerful carbon‐climate feedbacks over the coming century. To date, efforts to predict SOC dynamics have rested on pool‐based models, which assume classes of SOC with internally homogenous physicochemical properties. However, emerging evidence suggests that soil carbon turnover is not dominantly controlled by the chemistry of carbon inputs, but rather by restrictions on microbial access to organic matter in the spatially heterogeneous soil environment. The dynamic processes that control the physicochemical protection of carbon translate poorly to pool‐based SOC models; as a result, we are challenged to mechanistically predict how environmental change will impact movement of carbon between soils and the atmosphere. Here, we propose a novel conceptual framework to explore controls on belowground carbon cycling: P robabilistic R epresentation of O rganic M atter I nteractions within the S oil E nvironment (PROMISE). In contrast to traditional model frameworks, PROMISE does not attempt to define carbon pools united by common thermodynamic or functional attributes. Rather, the PROMISE concept considers how SOC cycling rates are governed by the stochastic processes that influence the proximity between microbial decomposers and organic matter, with emphasis on their physical location in the soil matrix. We illustrate the applications of this framework with a new biogeochemical simulation model that traces the fate of individual carbon atoms as they interact with their environment, undergoing biochemical transformations and moving through the soil pore space. We also discuss how the PROMISE framework reshapes dialogue around issues related to SOC management in a changing world. We intend the PROMISE framework to spur the development of new hypotheses, analytical tools, and model structures across disciplines that will illuminate mechanistic controls on the flow of carbon between plant, soil, and atmospheric pools. Abstract : Soil organic matter is traditionally conceptualized as a series of discrete and static pools, yet in reality, it undergoes continuous chemical and biological transformation. We present new conceptual and numerical models that reframe our perspective, emphasizing the constant flow of carbon on its journey from plant inputs to mineralization.