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Publications (10 of 16) Show all publications
Metcalfe, D. B., Cherif, M., Jepsen, J. U., Vindstad, O. P., Kristensen, J. A. & Belsing, U. (2019). Ecological stoichiometry and nutrient partitioning in two insect herbivores responsible for large-scale forest disturbance in the Fennoscandian subarctic. Ecological Entomology, 44(1), 118-128
Open this publication in new window or tab >>Ecological stoichiometry and nutrient partitioning in two insect herbivores responsible for large-scale forest disturbance in the Fennoscandian subarctic
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2019 (English)In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 44, no 1, p. 118-128Article in journal (Refereed) Published
Abstract [en]

1. Outbreaks of herbivorous insects can have large impacts on regional soil carbon (C) storage and nutrient cycling. In northernmost Europe, population outbreaks of several geometrid moth species regularly cause large‐scale defoliation in subarctic birch forests. An improved understanding is required of how leaf C and nutrients are processed after ingestion by herbivores and what this means for the quantity and quality of different materials produced (frass, bodies).

2. In this study, larvae of two geometrid species responsible for major outbreaks (Epirrita autumnata and Operophtera brumata) were raised on exclusive diets of Betula pubescens var. czerepanovii (N. I. Orlova) Hämet Ahti and two other abundant understorey species (Betula nanaVaccinium myrtillus). The quantities of C, nitrogen (N) and phosphorus (P) ingested and allocated to frass, bodies and (in the case of C) respired were recorded.

3. Overall, 23%, 70% and 48% of ingested C, N and P were allocated to bodies, respectively, rather than frass and (in the case of C) respiration. Operophtera brumata consistently maintained more constant body stoichiometric ratios of C, N and P than did E. autumnata, across the wide variation in physico‐chemical properties of plant diet supplied.

4. These observed differences and similarities on C and nutrient processing may improve researchers' ability to predict the amount and stoichiometry of frass and bodies generated after geometrid outbreaks.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2019
Keywords
Consumer-driven nutrient recycling, ecological stoichiometry, geometrid moth, homeostasis, stable isotope, subarctic birch forest
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-155625 (URN)10.1111/een.12679 (DOI)000454808500012 ()
Funder
Swedish Research Council, 2014-5177
Available from: 2019-01-28 Created: 2019-01-28 Last updated: 2019-01-28Bibliographically approved
Portalier, S. M. J., Fussmann, G. F., Loreau, M. & Cherif, M. (2019). The mechanics of predator-prey interactions: first principles of physics predict predator-prey size ratios. Functional Ecology, 33(2), 323-334
Open this publication in new window or tab >>The mechanics of predator-prey interactions: first principles of physics predict predator-prey size ratios
2019 (English)In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 33, no 2, p. 323-334Article in journal (Refereed) Published
Abstract [en]

Robust predictions of predator-prey interactions are fundamental for the understanding of food webs, their structure, dynamics, resistance to species loss, response to invasions and ecosystem function. Most current food web models measure parameters at the food web level to predict patterns at the same level. Thus, they are sensitive to the quality of the data and may be ineffective in predicting non-observed interactions and disturbed food webs. There is a need for mechanistic models that predict the occurrence of a predator-prey interaction based on lower levels of organization (i.e. the traits of organisms) and the properties of their environment. Here, we present such a model that focuses on the predation act itself. We built a Newtonian, mechanical model for the processes of searching, capturing and handling of a prey item by a predator. Associated with general metabolic laws, we predict the net energy gain from predation for pairs of pelagic or flying predator species and their prey depending on their body sizes. Predicted interactions match well with data from the most extensive predator-prey database, and overall model accuracy is greater than the allometric niche model. Our model shows that it is possible to accurately predict the structure of food webs using only a few mechanical traits. It underlines the importance of physical constraints in structuring food webs.

Keywords
body size, energy, mechanics, predation, trophic link
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-156879 (URN)10.1111/1365-2435.13254 (DOI)000458830500011 ()
Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2019-03-11Bibliographically approved
Creed, I. F., Bergström, A.-K., Trick, C. G., Grimm, N. B., Hessen, D. O., Karlsson, J., . . . Weyhenmeyer, G. A. (2018). Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes. Global Change Biology, 24(8), 3692-3714
Open this publication in new window or tab >>Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes
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2018 (English)In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, no 8, p. 3692-3714Article, review/survey (Refereed) Published
Abstract [en]

Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
atmospheric change, cyanobacteria, dissolved organic matter, food webs, lake, mercury, northern
National Category
Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-150465 (URN)10.1111/gcb.14129 (DOI)000437284700035 ()29543363 (PubMedID)
Funder
Swedish Research Council, AKB 2010-4675Swedish Research Council, RG 2013-5001
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-08-22Bibliographically approved
Cherif, M., Faithfull, C., Guo, J., Meunier, C. L., Sitters, J., Uszko, W. & Rivera Vasconcelos, F. (2017). An operational framework for the advancement of a molecule-to-biosphere stoichiometry theory. Frontiers in Marine Science, 4, Article ID 286.
Open this publication in new window or tab >>An operational framework for the advancement of a molecule-to-biosphere stoichiometry theory
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2017 (English)In: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 4, article id 286Article in journal (Refereed) Published
Abstract [en]

Biological stoichiometry is an approach that focuses on the balance of elements in biological interactions. It is a theory that has the potential to causally link material processes at all biological levels—from molecules to the biosphere. But the lack of a coherent operational framework has so far restricted progress in this direction. Here, we provide a framework to help infer how a stoichiometric imbalance observed at one level impacts all other biological levels. Our framework enables us to highlight the areas of the theory in need of completion, development and integration at all biological levels. Our hope is that this framework will contribute to the building of a more predictive theory of elemental transfers within the biosphere, and thus, to a better understanding of human-induced perturbations to the global biogeochemical cycles.

Place, publisher, year, edition, pages
Lausanne: Frontiers Media S.A., 2017
Keywords
biological organization, biological stoichiometry, consumer-driven nutrient recycling, ecological theory, theory integration, growth-rate hypothesis, light:nutrient hypothesis
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-139395 (URN)10.3389/fmars.2017.00286 (DOI)
Available from: 2017-09-15 Created: 2017-09-15 Last updated: 2018-11-28Bibliographically approved
Sitters, J., te Beest, M., Cherif, M., Giesler, R. & Olofsson, J. (2017). Interactive Effects Between Reindeer and Habitat Fertility Drive Soil Nutrient Availabilities in Arctic Tundra. Ecosystems (New York. Print), 20(7), 1266-1277
Open this publication in new window or tab >>Interactive Effects Between Reindeer and Habitat Fertility Drive Soil Nutrient Availabilities in Arctic Tundra
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2017 (English)In: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 20, no 7, p. 1266-1277Article in journal (Refereed) Published
Abstract [en]

Herbivores impact nutrient availability and cycling, and the net effect of herbivory on soil nutrients is generally assumed to be positive in nutrient-rich environments and negative in nutrient-poor ones. This is, however, far from a uniform pattern, and there is a recognized need to investigate any interactive effects of herbivory and habitat fertility (i.e., plant C/N ratios) on soil nutrient availabilities. We determined long-term effects of reindeer on soil extractable nitrogen (N) and phosphorus (P) and their net mineralization rates along a fertility gradient of plant carbon (C) to N and P ratios in arctic tundra. Our results showed that reindeer had a positive effect on soil N in the more nutrient-poor sites and a negative effect on soil P in the more nutrient-rich sites, which contrasts from the general consensus. The increase in N availability was linked to a decrease in plant and litter C/N ratios, suggesting that a shift in vegetation composition toward more graminoids favors higher N cycling. Soil P availability was not as closely linked to the vegetation and is likely regulated more by herbivore-induced changes in soil physical and chemical properties. The changes in soil extractable N and P resulted in higher soil N/P ratios, suggesting that reindeer could drive the vegetation toward P-limitation. This research highlights the importance of including both the elements N and P and conducting studies along environmental gradients in order to better understand the interactive effects of herbivory and habitat fertility on nutrient cycling and primary production.

Keywords
carbon, decomposition; grazing; herbivory, litter, microbial mineralization, nitrogen, nutrient cycling, phosphorus, plant stoichiometry
National Category
Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-135470 (URN)10.1007/s10021-017-0108-1 (DOI)000414175600003 ()
Available from: 2017-05-29 Created: 2017-05-29 Last updated: 2018-06-09Bibliographically approved
Cherif, M. & Elser, J. (2016). Ecological Stoichiometry. In: Oxford Bibliographies in Ecology: . Oxford Bibliographies
Open this publication in new window or tab >>Ecological Stoichiometry
2016 (English)In: Oxford Bibliographies in Ecology, Oxford Bibliographies, 2016Chapter in book (Refereed)
Abstract [en]

Ecological stoichiometry (ES) is the study of the balance of energy and multiple chemical elements in ecological interactions. Although much of the foundation of this field lies in studies of lakes (and especially of lake plankton), the application of ES has greatly expanded in 21st century, with extensions to streams, soils, grasslands, forests, and other ecosystems. This article provides a guide to recent introductory articles and reviews of the ES approach, to some of the foundational papers that preceded the formal definition of ES, and to a cross-section of papers dealing with biochemical, evolutionary, and ecological (especially biogeochemical) applications of ES. The field remains highly dynamic: a topic search on “ecolog stoichiometry” in ISI Web of Science yields more than 6,100 citations per year (in 2013; compared to less than five hundred in 1993). Thus, this annotated bibliography can only touch on the tip of this growing iceberg.

Place, publisher, year, edition, pages
Oxford Bibliographies, 2016
National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-130132 (URN)10.1093/obo/9780199830060-0146 (DOI)
Available from: 2017-01-12 Created: 2017-01-12 Last updated: 2018-06-09Bibliographically approved
diva2:949428
Open this publication in new window or tab >>Potential for Local Fertilization: A Benthocosm Test of Long-Term and Short-Term Effects of Mussel Excretion on the Plankton
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 6, article id e0156411Article in journal (Refereed) Published
Abstract [en]

Mussel aquaculture has expanded worldwide and it is important to assess its impact on the water column and the planktonic food web to determine the sustainability of farming practices. Mussel farming may affect the planktonic food web indirectly by excreting bioavailable nutrients in the water column (a short-term effect) or by increasing nutrient effluxes from bio-deposit-enriched sediments (a long-term effect). We tested both of these indirect effects in a lagoon by using plankton-enclosing benthocosms that were placed on the bottom of a shallow lagoon either inside of a mussel farm or at reference sites with no history of aquaculture. At each site, half of the benthocosms were enriched with seawater that had held mussels (excretion treatment), the other half received non-enriched seawater as a control treatment. We monitored nutrients ([PO43-] and [NH4+]), dissolved oxygen and plankton components (bacteria, the phytoplankton and the zooplankton) over 5 days. We found a significant relationship between long-term accumulation of mussel biodeposits in sediments, water-column nutrient concentrations and plankton growth. Effects of mussel excretion were not detected, too weak to be significant given the spatial and temporal variability observed in the lagoon. Effects of mussels on the water column are thus likely to be coupled to benthic processes in such semi-enclosed water bodies.

National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-123446 (URN)10.1371/journal.pone.0156411 (DOI)000377184700042 ()27249793 (PubMedID)
Available from: 2016-07-19 Created: 2016-07-04 Last updated: 2018-06-07Bibliographically approved
Portalier, S. M. J., Cherif, M., Zhang, L., Fussmann, G. F. & Loreau, M. (2016). Size-related effects of physical factors on phytoplankton communities. Ecological Modelling, 323, 41-50
Open this publication in new window or tab >>Size-related effects of physical factors on phytoplankton communities
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2016 (English)In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 323, p. 41-50Article in journal (Refereed) Published
Abstract [en]

Phytoplankton communities are influenced by light availability. Therefore, one factor promoting phytoplankton species persistence is their ability to stay within the euphotic zone. This ability is determined by the interplay between species mass, buoyancy and dispersion, which are driven by physical factors. In this study, we investigate how these physical factors and light-use efficiency, all correlated with cell size, influence species persistence. Our model shows, first, that species can persist only within a size-dependent range of turbulence strength. The minimal level of turbulence required for persistence increases drastically with cell size, while all species reach similar maximal levels of turbulence. Second, the maximal water column depth allowing persistence is also size-dependent: large cells show a maximal depth at both low and high turbulence strength, while small cells show this pattern only at high turbulence strength. This study emphasizes the importance of the physical medium in ecosystems and its interplay with cell size for phytoplankton dynamics and bloom condition.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Turbulence, Light limitation, Critical depth, Phytoplankton bloom
National Category
Environmental Sciences Ecology
Identifiers
urn:nbn:se:umu:diva-124270 (URN)10.1016/j.ecolmodel.2015.12.003 (DOI)000378100200004 ()
Available from: 2016-08-01 Created: 2016-07-29 Last updated: 2018-06-07Bibliographically approved
Cherif, M. (2016). Stoichiometry and Population Growth in Osmotrophs and Non‐Osmotrophs. In: eLS: (pp. 1-6). John Wiley & Sons
Open this publication in new window or tab >>Stoichiometry and Population Growth in Osmotrophs and Non‐Osmotrophs
2016 (English)In: eLS, John Wiley & Sons, 2016, p. 1-6Chapter in book (Refereed)
Abstract [en]

Growth is a process fundamental to life. It implies an increase in not only energy and information but also matter content. Recent advances in ecology have demonstrated that the elemental composition of organisms – their stoichiometry – is inextricably linked to their growth rate. Unbalances between the demands of elements for growth and their relative availabilities often result in elemental limitation. Also, different cellular components have different elemental compositions, and thus changes in allocation between uptake and assembly machineries affect both growth rate and elemental composition at the organismal level. Osmotrophs (including autotrophs) acquire essential elements through a vast set of separate molecules, resulting in more flexible stoichiometries compared to non-osmotrophs that ingest their preys in one package. Relationships between elemental composition and growth rate should be considered differently for individuals and for populations, as processes and mechanisms differ between the two scales, and more generally among the various biological scales.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
Keywords
droop model, autotrophs, osmotrophs, metazoans, elemental limitation, homeostasis, uptake, compensatory feeding, ribosomes, phosphorus, excretion
National Category
Ecology Evolutionary Biology
Identifiers
urn:nbn:se:umu:diva-130017 (URN)10.1002/9780470015902.a0026353 (DOI)9780470015902 (ISBN)
Available from: 2017-01-11 Created: 2017-01-11 Last updated: 2018-06-09Bibliographically approved
Cherif, M. & Loreau, M. (2013). Plant - herbivore -decomposer stoichiometric mismatches and nutrientcycling in ecosystems. Proceedings of the Royal Society of London. Biological Sciences, 280(1754), 20122453
Open this publication in new window or tab >>Plant - herbivore -decomposer stoichiometric mismatches and nutrientcycling in ecosystems
2013 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 280, no 1754, p. 20122453-Article in journal (Refereed) Published
Abstract [en]

Plant stoichiometry is thought to have a major influence on how herbivores affect nutrient availability in ecosystems. Most conceptual models predict that plants with high nutrient contents increase nutrient excretion by herbivores, in turn raising nutrient availability. To test this hypothesis, we built a stoichiometrically explicit model that includes a simple but thorough description of the processes of herbivory and decomposition. Our results challenge traditional views of herbivore impacts on nutrient availability in many ways. They show that the relationship between plant nutrient content and the impact of herbivores predicted by conceptual models holds only at high plant nutrient contents. At low plant nutrient contents, the impact of herbivores is mediated by the mineralization/immobilization of nutrients by decomposers and by the type of resource limiting the growth of decomposers. Both parameters are functions of the mismatch between plant and decomposer stoichiometries. Our work provides new predictions about the impacts of herbivores on ecosystemfertility that depend on critical interactions between plant, herbivore and decomposer stoichiometries in ecosystems.

Keywords
herbivory, mineralization, model, nutrient cycling, nutrition, ecological stoichiometry
National Category
Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-80850 (URN)10.1098/rspb.2012.2453 (DOI)000313663700002 ()
Available from: 2013-09-26 Created: 2013-09-26 Last updated: 2018-06-08Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0107-9374

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