Animating the Carbon Cycle

Schmitz, Oswald J.; Raymond, Peter A.; Estes, James A.; Kurz, Werner A.; Holtgrieve, Gordon W.; Ritchie, Mark E.; Schindler, Daniel E.; Spivak, Amanda C.; Wilson, Rod W.; Bradford, Mark A.; Christensen, Villy; Deegan, Linda A.; Smetacek, Victor; Vanni, Michael J.; Wilmers, Christopher C.

doi:10.1007/s10021-013-9715-7

Cited by 189 publications

(223 citation statements)

References 75 publications

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“…Our theory should also help predict human impacts on the carbon cycle on scales from local ecosystems to the biosphere. For example, overharvesting of large animals can significantly alter ecosystem biomass and GPP, impacting carbon residence times (3,(36)(37)(38). Both deforestation, which replaces A B C Fig.…”

Section: Discussionmentioning

confidence: 99%

Metabolic theory predicts whole-ecosystem properties

Schramski

Dell

Grady

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

138

129

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Understanding the effects of individual organisms on material cycles and energy fluxes within ecosystems is central to predicting the impacts of human-caused changes on climate, land use, and biodiversity. Here we present a theory that integrates metabolic (organism-based bottom-up) and systems (ecosystem-based topdown) approaches to characterize how the metabolism of individuals affects the flows and stores of materials and energy in ecosystems. The theory predicts how the average residence time of carbon molecules, total system throughflow (TST), and amount of recycling vary with the body size and temperature of the organisms and with trophic organization. We evaluate the theory by comparing theoretical predictions with outputs of numerical models designed to simulate diverse ecosystem types and with empirical data for real ecosystems. Although residence times within different ecosystems vary by orders of magnitude-from weeks in warm pelagic oceans with minute phytoplankton producers to centuries in cold forests with large tree producers-as predicted, all ecosystems fall along a single line: residence time increases linearly with slope = 1.0 with the ratio of whole-ecosystem biomass to primary productivity (B/P). TST was affected predominantly by primary productivity and recycling by the transfer of energy from microbial decomposers to animal consumers. The theory provides a robust basis for estimating the flux and storage of energy, carbon, and other materials in terrestrial, marine, and freshwater ecosystems and for quantifying the roles of different kinds of organisms and environments at scales from local ecosystems to the biosphere. metabolic theory | systems ecology | total system throughflow | residence time | cycling I n most ecosystems, energy and materials flow through trophic networks comprised of plant primary producers, animal consumers, and microbial decomposers (Fig. 1). The individual organisms that make up these networks control the storage and flux of energy, carbon, and other materials. Consequently, a theoretical framework that can account for how different kinds of organisms and ecosystems affect fluxes and stores of energy and materials in ecosystems is central to understanding the carbon cycle of the biosphere and to predicting the impacts of humancaused changes in climate, land use, and biodiversity (1-3). Although it has long been recognized that different kinds of organisms play important roles in the processing of energy and materials in ecosystems, existing treatments are incomplete. Most studies have focused on particular trophic levels, such as primary producers or herbivores, specific ecosystem types, such as tropical forest or pelagic marine, or single species, such as top predators or ecosystem engineers (4-14). Still missing is a simple mechanistic theory that can make precise, quantitative predictions based on the mechanistic relationships between traits of the organisms in the different trophic levels and whole-ecosystem properties, such as carbon flux or recycling.Two main t...

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Section: Discussionmentioning

confidence: 99%

Metabolic theory predicts whole-ecosystem properties

Schramski

Dell

Grady

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

138

129

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“…Despite continuous refinement over the past decades, estimates of the global carbon cycle still show large discrepancies between potential and observed carbon fluxes (Ballantyne et al, 2012;Schmitz et al, 2014). Soils contain more carbon than the atmosphere and above-ground vegetation together and play an important role for many of the recently adopted UN Sustainable Development Goals.…”

Section: Introductionmentioning

confidence: 99%

“…In a review focusing mostly on large mammals, terrestrial herbivores and aquatic ecosystems, Schmitz et al (2014) recently called for "animating the carbon cycle". Bardgett et al (2013) argued that differential responses of various trophic groups of above-ground and below-ground organisms to global change can result in a decoupling of plant-soil interactions, with potentially irreversible consequences for carbon cycling.…”

Section: Introductionmentioning

confidence: 99%

Soil fauna: key to new carbon models

Filser

Faber

Tiunov

et al. 2016

SOIL

178

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Abstract. Soil organic matter (SOM) is key to maintaining soil fertility, mitigating climate change, combatting land degradation, and conserving above-and below-ground biodiversity and associated soil processes and ecosystem services. In order to derive management options for maintaining these essential services provided by soils, policy makers depend on robust, predictive models identifying key drivers of SOM dynamics. Existing SOM models and suggested guidelines for future SOM modelling are defined mostly in terms of plant residue quality and input and microbial decomposition, overlooking the significant regulation provided by soil fauna. The fauna controls almost any aspect of organic matter turnover, foremost by regulating the activity and functional composition of soil microorganisms and their physical-chemical connectivity with soil organic matter. We demonstrate a very strong impact of soil animals on carbon turnover, increasing or decreasing it by several dozen percent, sometimes even turning C sinks into C sources or vice versa. This is demonstrated not only for earthworms and other larger invertebrates but also for smaller fauna such as Collembola. We suggest that inclusion of soil animal activities (plant residue consumption and bioturbation altering the formation, depth, hydraulic properties and physical heterogeneity of soils) can fundamentally affect the predictive outcome of SOM models. Understanding direct and indirect impacts of soil fauna on nutrient availability, carbon sequestration, greenhouse gas emissions and plant growth is key to the understanding of SOM dynamics in the context of global carbon cycling models. We argue that explicit consideration of soil fauna is essential to make realistic modelling predictions on SOM dynamics and to detect expected non-linear responses of SOM dynamics to global change. WePublished by Copernicus Publications on behalf of the European Geosciences Union. 566 J. Filser et al.: Soil fauna: key to new carbon models present a decision framework, to be further developed through the activities of KEYSOM, a European COST Action, for when mechanistic SOM models include soil fauna. The research activities of KEYSOM, such as field experiments and literature reviews, together with dialogue between empiricists and modellers, will inform how this is to be done.

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“…Despite their potential relevance for the land carbon-climate feedback, the capacity for animalmicrobial interactions to mediate decomposition responses to global change remains untested. The failure to incorporate animals and their interactions with microbial communities into global decomposition models has been highlighted as a critical limitation in our understanding of carbon cycling under current and future climate scenarios (21,22).…”

mentioning

confidence: 99%

Biotic interactions mediate soil microbial feedbacks to climate change

Crowther

Thomas

Maynard

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

218

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Decomposition of organic material by soil microbes generates an annual global release of 50–75 Pg carbon to the atmosphere, ∼7.5–9 times that of anthropogenic emissions worldwide. This process is sensitive to global change factors, which can drive carbon cycle–climate feedbacks with the potential to enhance atmospheric warming. Although the effects of interacting global change factors on soil microbial activity have been a widespread ecological focus, the regulatory effects of interspecific interactions are rarely considered in climate feedback studies. We explore the potential of soil animals to mediate microbial responses to warming and nitrogen enrichment within a long-term, field-based global change study. The combination of global change factors alleviated the bottom-up limitations on fungal growth, stimulating enzyme production and decomposition rates in the absence of soil animals. However, increased fungal biomass also stimulated consumption rates by soil invertebrates, restoring microbial process rates to levels observed under ambient conditions. Our results support the contemporary theory that top-down control in soil food webs is apparent only in the absence of bottom-up limitation. As such, when global change factors alleviate the bottom-up limitations on microbial activity, top-down control becomes an increasingly important regulatory force with the capacity to dampen the strength of positive carbon cycle–climate feedbacks.

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Animating the Carbon Cycle

Cited by 189 publications

References 75 publications

Metabolic theory predicts whole-ecosystem properties

Metabolic theory predicts whole-ecosystem properties

Soil fauna: key to new carbon models

Biotic interactions mediate soil microbial feedbacks to climate change

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