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N and P constrain C in ecosystems under climate change: Role of nutrient redistribution, accumulation, and stoichiometry

Ed Rastetter·Bonnie Kwiatkowski·David Kicklighter·Audrey Barker Plotkin·Helene Genet·Jesse Nippert·Kimberly O’Keefe·Steven S. Perakis·Stephen Porder·Sarah Roley·Roger W. Ruess·Jonathan R. Thompson·William Wieder·Kevin WIlcox·Ruth Yanai
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Abstract

We use the Multiple Element Limitation (MEL) model to examine responses of twelve ecosystems to elevated carbon dioxide (CO 2 ), warming, and 20% decreases or increases in precipitation. Ecosystems respond synergistically to elevated CO 2 , warming, and decreased precipitation combined because higher water-use efficiency with elevated CO 2 and higher fertility with warming compensate for responses to drought. Response to elevated CO 2 , warming, and increased precipitation combined is additive. We analyze changes in ecosystem carbon (C) based on four nitrogen (N) and four phosphorus (P) attribution factors: (1) changes in total ecosystem N and P, (2) changes in N and P distribution between vegetation and soil, (3) changes in vegetation C:N and C:P ratios, and (4) changes in soil C:N and C:P ratios. In the combined CO 2 and climate change simulations, all ecosystems gain C. The contributions of these four attribution factors to changes in ecosystem C storage varies among ecosystems because of differences in the initial distributions of N and P between vegetation and soil and the openness of the ecosystem N and P cycles. The net transfer of N and P from soil to vegetation dominates the C response of forests. For tundra and grasslands, the C gain is also associated with increased soil C:N and C:P. In ecosystems with symbiotic N fixation, C gains resulted from N accumulation. Because of differences in N versus P cycle openness and the distribution of organic matter between vegetation and soil, changes in the N and P attribution factors do not always parallel one another. Differences among ecosystems in C-nutrient interactions and the amount of woody biomass interact to shape ecosystem C sequestration under simulated global change. We suggest that future studies quantify the openness of the N and P cycles and changes in the distribution of C, N, and P among ecosystem components, which currently limit understanding of nutrient effects on C sequestration and responses to elevated CO 2 and climate change.

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Ed Rastetter, Bonnie Kwiatkowski, David Kicklighter, Audrey Barker Plotkin, Helene Genet, Jesse Nippert, Kimberly O’Keefe, Steven S. Perakis, Stephen Porder, Sarah Roley, Roger W. Ruess, Jonathan R. Thompson, William Wieder, Kevin WIlcox, Ruth Yanai. 2022-07-25. N and P constrain C in ecosystems under climate change: Role of nutrient redistribution, accumulation, and stoichiometry. https://doi.org/10.1002/eap.2684

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