Microbial and animal nutrient limitation change the distribution of nitrogen within coupled green and brown food chains

Buchkowski, Robert W.; Leroux, Shawn J.; Schmitz, Oswald J.

doi:10.1002/ecy.2674

Cited by 18 publications

(27 citation statements)

References 43 publications

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“…The + predator treatment also allowed us to account for potential positive indirect effects of predators on primary production through consumer driven nutrient recycling (Buchkowski et al . 2019) or regulate CO 2 flux through detrital pathways (Atwood et al . 2013, 2014a).…”

Section: Methodsmentioning

confidence: 99%

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Letter: Trophic interactions regulate peatland carbon cycling

Wyatt¹,

McCann²,

Rober³

et al. 2021

Ecology Letters

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Peatlands are the most efficient natural ecosystems for long‐term storage of atmospheric carbon. Our understanding of peatland carbon cycling is based entirely on bottom‐up controls regulated by low nutrient availability. Recent studies have shown that top‐down controls through predator‐prey dynamics can influence ecosystem function, yet this has not been evaluated in peatlands to date. Here, we used a combination of nutrient enrichment and trophic‐level manipulation to test the hypothesis that interactions between nutrient availability (bottom‐up) and predation (top‐down) influence peatland carbon fluxes. Elevated nutrients stimulated bacterial biomass and organic matter decomposition. In the absence of top‐down regulation, carbon dioxide (CO2) respiration driven by greater decomposition was offset by elevated algal productivity. Herbivores accelerated CO2 emissions by removing algal biomass, while predators indirectly reduced CO2 emissions by muting herbivory in a trophic cascade. This study demonstrates that trophic interactions can mitigate CO2 emissions associated with elevated nutrient levels in northern peatlands.

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Section: Methodsmentioning

confidence: 99%

“…2000; Buchkowski et al . 2019). There is growing evidence that higher trophic levels in both terrestrial and aquatic food webs, in turn, can exert important control on nutrient availability, with consequences for primary productivity and other aspects of ecosystem carbon cycling (Estes et al .…”

Section: Introductionmentioning

confidence: 99%

Letter: Trophic interactions regulate peatland carbon cycling

Wyatt¹,

McCann²,

Rober³

et al. 2021

Ecology Letters

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“…If the parameter p j is the maximum efficiency, then this corresponds a state of carbon limitation. When experiencing carbon limitation, an organism grows at a rate set by the available carbon, while the excess nitrogen is mineralized (Buchkowski et al., 2019; Sterner & Elser, 2002). If the excess nitrogen is negative and the organism cannot immobilize nitrogen, then we can reduce production efficiency until the organism's nitrogen demands are met.…”

Section: Methodsmentioning

confidence: 99%

“…For example, organism production efficiency accounts for the proportion of incoming carbon that is respired and therefore sets the maximum ratio of carbon to nutrients on which an organism can survive (de Ruiter et al., 1994). Production efficiency is typically fixed in soil food web models meaning that these models assume that organisms maintain a constant level of carbon limitation (Buchkowski et al., 2019; Frost et al., 2006). In reality, production efficiency, which is often called carbon use efficiency in microbial decomposition models, should decrease when organisms feed on diets with a higher C:N ratios (Schimel & Weintraub, 2003; Sterner & Elser, 2002).…”

Section: Introductionmentioning

confidence: 99%

Stoichiometric and structural uncertainty in soil food web models

Buchkowski

Lindo

2020

Functional Ecology

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1. Soil food web models are a powerful tool for calculating the carbon and nitrogen mineralized by different soil organisms. Two limitations of the current models are that they use (a) fixed parameters for determining the relative efficiency of carbon and nitrogen conversion and (b) a generic set of trophic species (i.e. nodes). 2. We propose a new method for analysing soil food webs that varies production efficiency and diet mechanistically with resource stoichiometry. Then, we calculated how the lumping or splitting of trophic species affects carbon and nitrogen mineralization for both net mineralization rates as well as the distribution of mineralization (i.e. sources of mineralization). Our models with additional stoichiometric details better represent organisms that consume basal resources with high C:N ratios. 3. This is important because we show that lumping together trophic species at low trophic levels, which often differ in C:N ratios (i.e. microbial taxa), causes the largest deviations in estimates of carbon and nitrogen mineralization. One reason for the large effect of C:N ratio is that it impacts diet and production efficiency in our stoichiometric model. Conversely, lumping together species at higher trophic levels causes the largest errors when those species have different production and assimilation efficiencies. Finally, we demonstrate that differences in death rate and biomass are mostly important when lumping species that have different diets. 4. We suggest that C:N ratios are especially important when grouping microbial taxa because microbial C:N ratios vary widely and microbes feed at low trophic levels where differences in C:N ratio mattered the most. Conversely lumping higher consumers will be most problematic when they have differences in the conversion efficiencies. We provide an approach to calculate structural error and report it with parameter uncertainty. Then, we demonstrate, using oribatid mites as an example, that considering the life history of different taxa can help us group organisms more efficiently into trophic species. In doing so, we provide a way to reduce and report the uncertainty in soil food web models and to stimulate future empirical work measuring key life history parameters.

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“…Food web ecology generally separates basal resources into two separate or alternative pathways, autotrophic (green) and heterotrophic or detrital (brown) (Hairston et al 1960; Moore et al 2004). However, more recent studies suggest that organisms frequently consume organic matter from both autotrophic and detrital pathways rather than from either pathway alone (Wolkovich et al 2014; Buchkowski et al 2019). For example, in ecosystems where detritus is the primary source of organic matter (i.e., a detrital‐based system; Wissinger et al 2018) animal diets can be supplemented by temporary increases in autotrophic production (i.e., green energy; Crenier et al 2017).…”

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confidence: 99%

Greening of the boreal peatland food web: Periphyton supports secondary production in northern peatlands

Ferguson

Slagle

McCann

et al. 2021

Limnology & Oceanography

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Characterizing spatial and temporal variability of food web dynamics is necessary to predict how wetter and more nutrient-rich conditions expected with climate change will influence the fate of organic matter within northern peatlands. The goals of this study were to (1) document spatial and temporal variability in the contribution of periphyton to peatland food webs using isotope analysis ( 13 C and 15 N), and (2) quantify the influence of increased nutrient availability on primary and secondary production across a gradient of rich, moderate, and poor fen peatlands common to the northern boreal biome. We established replicate m 2 plots within each fen located in interior Alaska to quantify periphyton (algae and bacteria) and macroinvertebrate biomass with and without nutrient addition throughout a growing season (May-August). Stable isotope analysis showed that periphyton contributedx = 65% of organic matter to the food web over time and across fens compared to x = 7% from plants or detritus. The transfer of basal resources was reflected in an increase in herbivore biomass as algal biomass increased over time in all fens, followed by an increase in predatory macroinvertebrates during the latter part of the growing season. Furthermore, all measures of periphyton and macroinvertebrate biomass were enhanced by nutrient addition. These data provide insight into patterns of natural variation within the aquatic food web of boreal peatlands and show that basal resources within this ecosystem, which are generally considered to be "detritus-based," are actually driven by periphyton with minimal input from plant detrital pathways.

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Microbial and animal nutrient limitation change the distribution of nitrogen within coupled green and brown food chains

Cited by 18 publications

References 43 publications

Letter: Trophic interactions regulate peatland carbon cycling

Letter: Trophic interactions regulate peatland carbon cycling

Stoichiometric and structural uncertainty in soil food web models

Greening of the boreal peatland food web: Periphyton supports secondary production in northern peatlands

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