Low‐to‐moderate nitrogen and phosphorus concentrations accelerate microbially driven litter breakdown rates

Kominoski, John S.; Rosemond, Amy D.; Benstead, Jonathan P.; Gulis, Vladislav; Maerz, John C.; Manning, David W. P.

doi:10.1890/14-1113.1

Cited by 64 publications

(57 citation statements)

References 31 publications

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“…Regular measures of microcosm water chemistry could provide microbial uptake and release or be fit to Michaelis-Menten kinetics models (O'Brien & Dodds, 2008;Cheever et al, 2012); however, this approach would be better suited for a greater number of levels across a nutrient gradient with frequent flushing and replenishment of nutrients. The range of microbial respiration rates (0.024-0.892 lg O 2 mg À1 AFDM h À1 ) also closely resembled that of red maple in flowing experimental streams (0.066-0.597 lg O 2 mg À1 AFDM h À1 ; Kominoski et al, 2015). Contrasting decomposition across treatments also indicates insights to be gained by comparison of response variables at similar stages of decomposition (Cheever et al, 2013), but such analysis would surpass the scope of this study.…”

Section: Conclusion and Caveatsmentioning

confidence: 60%

Light and dissolved phosphorus interactively affect microbial metabolism, stoichiometry and decomposition of leaf litter

et al. 2016

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Summary In aquatic settings, light can stimulate algal growth to affect microbial transformation of organic substrates. These effects may depend on dissolved nutrients that differentially constrain microbial autotrophy and heterotrophy to drive contrasting carbon (C) and phosphorus (P) dynamics during decomposition. We incubated sugar maple (Acer saccharum) litter under three dissolved P amendments (0, 50 or 500 μg L−1 P) and two light levels (14 or 475 μmol photons m−2 s−1) in laboratory microcosms. We measured litter chlorophyll a, microbial respiration and net metabolism, carbon:nitrogen (C:N) and C:P content, microbial P uptake and release and litter decomposition over 134 days. Elevated dissolved P increased algal biomass in the high‐light treatment and magnified net heterotrophy and autotrophy in the low‐ and high‐light treatments, respectively. Litter C:P and C:N declined as dissolved P increased, and litter C:P was further reduced by high light only in the highest P treatment. Microbial P uptake fluxes peaked under moderate P and high light, whereas P release fluxes were consistently low throughout the experiment. The percent of P uptake that was released was significantly higher under low light. High light stimulated decomposition under low P but slowed decomposition under high P, suggesting increased nutrients weakened algal priming of litter decomposition. Our study suggests factors controlling the degree of autotrophy versus heterotrophy on organic matter, such as light and nutrient availability, may interactively shift litter C and P dynamics during decomposition.

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Section: Conclusion and Caveatsmentioning

confidence: 60%

Light and dissolved phosphorus interactively affect microbial metabolism, stoichiometry and decomposition of leaf litter

et al. 2016

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“…Notably, increased microbial biomass also enhances the quality of detrital C, through accumulation of microbial lipids, soluble carbohydrates, and protein that are nutritionally valuable compared to plant polysaccharides like cellulose and lignin that dominate detrital substrate C and are resistant to breakdown and assimilation (Martin et al, 1980; Chung and Suberkropp, 2009a,b). As elevated nutrients stimulate microbial growth, increased decomposition rates often accompany nutrient enrichment (Ferreira et al, 2015; Kominoski et al, 2015; Manning et al, 2015, 2016), stimulating C loss from ecosystems (Benstead et al, 2009; Rosemond et al, 2015). In this way, nutrient enrichment increases the quality (nutrient:C) of basal food resources in both green and brown food webs.…”

Section: Literature Review – Comparing Ecological Stoichiometry Of Grmentioning

confidence: 99%

Comparing the Ecological Stoichiometry in Green and Brown Food Webs – A Review and Meta-analysis of Freshwater Food Webs

Evans‐White

Halvorson

2017

Front. Microbiol.

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The framework of ecological stoichiometry was developed primarily within the context of “green” autotroph-based food webs. While stoichiometric principles also apply in “brown” detritus-based systems, these systems have been historically understudied and differ from green ones in several important aspects including carbon (C) quality and the nutrient [nitrogen (N) and phosphorus (P)] contents of food resources for consumers. In this paper, we review work over the last decade that has advanced the application of ecological stoichiometry from green to brown food webs, focusing on freshwater ecosystems. We first review three focal areas where green and brown food webs differ: (1) bottom–up controls by light and nutrient availability, (2) stoichiometric constraints on consumer growth and nutritional regulation, and (3) patterns in consumer-driven nutrient dynamics. Our review highlights the need for further study of how light and nutrient availability affect autotroph–heterotroph interactions on detritus and the subsequent effects on consumer feeding and growth. To complement this conceptual review, we formally quantified differences in stoichiometric principles between green and brown food webs using a meta-analysis across feeding studies of freshwater benthic invertebrates. From 257 datasets collated across 46 publications and several unpublished studies, we compared effect sizes (Pearson’s r) of resource N:C and P:C on growth, consumption, excretion, and egestion between herbivorous and detritivorous consumers. The meta-analysis revealed that both herbivore and detritivore growth are limited by resource N:C and P:C contents, but effect sizes only among detritivores were significantly above zero. Consumption effect sizes were negative among herbivores but positive for detritivores in the case of both N:C and P:C, indicating distinct compensatory feeding responses across resource stoichiometry gradients. Herbivore P excretion rates responded significantly positively to resource P:C, whereas detritivore N and P excretion did not respond; detritivore N and P egestion responded positively to resource N:C and P:C, respectively. Our meta-analysis highlights resource N and P contents as broadly limiting in brown and green benthic food webs, but indicates contrasting mechanisms of limitation owing to differing consumer regulation. We suggest that green and brown food webs share fundamental stoichiometric principles, while identifying specific differences toward applying ecological stoichiometry across ecosystems.

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“…Added N and P both accelerate C loss in detritus-based streams through enhanced organic matter breakdown and export (Benstead et al, 2009; Rosemond et al, 2015; Manning et al, 2016), as well as through substrate-specific and whole-stream ER (Suberkropp et al, 2010; Kominoski et al, 2017). Litter breakdown rates are constrained by microbial nutrient limitation (both N and P) at low-to-moderate concentrations through changes in litter C:N and C:P stoichiometry (Kominoski et al, 2015; Manning et al, 2015). These collective findings emphasize the importance of microbial processes on ecosystem C loss and the potential for long-term vulnerability to sustained C losses with sustained or increased N and P availability (Alexander and Smith, 2006), which ultimately can be linked to nutrient stoichiometry.…”

Section: Empirical Assessmentsmentioning

confidence: 99%

Bridging Food Webs, Ecosystem Metabolism, and Biogeochemistry Using Ecological Stoichiometry Theory

et al. 2017

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Although aquatic ecologists and biogeochemists are well aware of the crucial importance of ecosystem functions, i.e., how biota drive biogeochemical processes and vice-versa, linking these fields in conceptual models is still uncommon. Attempts to explain the variability in elemental cycling consequently miss an important biological component and thereby impede a comprehensive understanding of the underlying processes governing energy and matter flow and transformation. The fate of multiple chemical elements in ecosystems is strongly linked by biotic demand and uptake; thus, considering elemental stoichiometry is important for both biogeochemical and ecological research. Nonetheless, assessments of ecological stoichiometry (ES) often focus on the elemental content of biota rather than taking a more holistic view by examining both elemental pools and fluxes (e.g., organismal stoichiometry and ecosystem process rates). ES theory holds the promise to be a unifying concept to link across hierarchical scales of patterns and processes in ecology, but this has not been fully achieved. Therefore, we propose connecting the expertise of aquatic ecologists and biogeochemists with ES theory as a common currency to connect food webs, ecosystem metabolism, and biogeochemistry, as they are inherently concatenated by the transfer of carbon, nitrogen, and phosphorous through biotic and abiotic nutrient transformation and fluxes. Several new studies exist that demonstrate the connections between food web ecology, biogeochemistry, and ecosystem metabolism. In addition to a general introduction into the topic, this paper presents examples of how these fields can be combined with a focus on ES. In this review, a series of concepts have guided the discussion: (1) changing biogeochemistry affects trophic interactions and ecosystem processes by altering the elemental ratios of key species and assemblages; (2) changing trophic dynamics influences the transformation and fluxes of matter across environmental boundaries; (3) changing ecosystem metabolism will alter the chemical diversity of the non-living environment. Finally, we propose that using ES to link nutrient cycling, trophic dynamics, and ecosystem metabolism would allow for a more holistic understanding of ecosystem functions in a changing environment.

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Low‐to‐moderate nitrogen and phosphorus concentrations accelerate microbially driven litter breakdown rates

Cited by 64 publications

References 31 publications

Light and dissolved phosphorus interactively affect microbial metabolism, stoichiometry and decomposition of leaf litter

Light and dissolved phosphorus interactively affect microbial metabolism, stoichiometry and decomposition of leaf litter

Comparing the Ecological Stoichiometry in Green and Brown Food Webs – A Review and Meta-analysis of Freshwater Food Webs

Bridging Food Webs, Ecosystem Metabolism, and Biogeochemistry Using Ecological Stoichiometry Theory

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