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  • N and P constrain C in ecosystems under climate change: Role of nutrient redistribution, accumulation, and stoichiometry
Title: N and P constrain C in ecosystems under climate change: Role of nutrient redistribution, accumulation, and stoichiometry
We use the Multiple Element Limitation (MEL) model to examine the responses of twelve ecosystems - from the arctic to the tropics and from grasslands to forests - to elevated carbon dioxide (CO2), warming, and 20% decreases or increases in annual precipitation. The ecosystems respond synergistically to elevated CO2, warming, and decreased precipitation combined because higher water use efficiency with elevated CO2 and higher fertility with warming compensate for the responses to drought. The response to elevated CO2, warming, and increased precipitation combined is additive. We analyze changes in ecosystem carbon (C) sequestration based on four nitrogen (N) and four phosphorus (P) attribution factors of the ecosystem: (1) changes in total N and P in the ecosystem, (2) changes in the distribution of N and P 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 CO2 and climate change simulations, all ecosystems gain C. The relative contribution of changes in these four N and P 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 (low C:N and C:P) to vegetation (high C:N and C:P) dominates the C response of forests. For tundra and grassland ecosystems, the C gain is also associated with an increase in soil C:N and C:P. In ecosystems with symbiotic N fixation, gains in C resulted from the accumulation of N and sometimes P. Because of differences in the openness of the N versus P cycles and the distribution of organic matter between vegetation and soil, changes in the N attribution factors do not always parallel changes in the P attribution factors. These findings highlight how differences among ecosystems in C-nutrient interactions and the amount of woody biomass interact to shape ecosystem C sequestration under simulated global change. By using a single model framework across multiple ecosystems, we suggest that a better understanding of the factors influencing the openness of the N and P cycles, controls on N and P distribution within ecosystems, and controls on ecosystem stoichiometry is needed to improve the representation of nutrient effects on C sequestration in ecosystems and their responses to elevated CO2 and climate change.  more » « less
Award ID(s):
1651722 1637459 2220863 1637685 1832042 2025755 2103539 1832210 1636476 2025849
PAR ID:
10343150
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ;
Date Published:
Journal Name:
Ecological Applications
ISSN:
1051-0761
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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