Project

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Climate change impacts on soil N:P stoichiometry and consequent feedbacks on plant-microbe interactions in Australian grasslands

Applicant Mariotte Pierre
Number 154648
Funding scheme Advanced Postdoc.Mobility
Research institution Laboratory of Ecological Systems ECOS EPFL
Institution of higher education Institution abroad - IACH
Main discipline Ecology
Start/End 01.10.2014 - 31.07.2016
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All Disciplines (2)

Discipline
Ecology
Environmental Research

Keywords (9)

ecosystem functioning; community ecology; phosphorus; climate change; drought; fire; nitrogen; stoichiometry; competition

Lay Summary (French)

Lead
La sécheresse et le feu influencent l’apport en azote (N) et phosphore (P) dans le sol avec des effets différents selon les types de sol. Les modifications des contraintes stoichiométriques du sol pour ces deux éléments influencent directement leur absorption par les plantes et les micro-organismes. En revanche, leurs effets sur la compétition entre les plantes et les micro-organismes pour l’utilisation de ces ressources sont encore peu étudiés.
Lay summary

Dans cette étude, nous utiliserons une approche expérimentale en prélevant des échantillons de sol provenant de placettes soumises à la sécheresse d’une part et au feu d’autre part sur 3 sites expérimentaux à caractéristiques pédologiques contrastées. Ces échantillons serviront de base à l’élaboration d’une expérience en serre visant à tester la compétition entre les plantes et les micro-organismes pour l’azote et le phosphore suivant les contraintes stoichiométriques influencées par l’interaction entre le type de sols et les facteurs climatiques. Pour évaluer la compétition plante-microbes pour les ressources, nous injecterons des traceurs isotopiques (15N et 32P) dans le sol, et nous suivrons l’évolution de l’absorption relative de ces éléments entre les plantes et les micro-organismes.

Les résultats de cette expérience permettront d’identifier les mécanismes relatifs aux effets de la sécheresse et du feu en prenant en compte les effets induits sur les contraintes stoichiométriques de l’azote et du phosphore et leurs conséquences sur la compétition pour les ressources entre les plantes et les micro-organismes dans différents types de sol. L’évaluation des effets de la sécheresse ou du feu dans différents types de sol aura également d’importantes implications pour la gestion des prairies australiennes dans les années futures.

Direct link to Lay Summary Last update: 18.07.2014

Responsible applicant and co-applicants

Employees

Publications

Publication
Plant uptake of nitrogen and phosphorus among grassland species affected by drought along a soil phosphorus gradient
Mariotte Pierre, Creswell Tom, Johansen Mathew, Harisson Jennifer, Keitel Claudia, Dijkstra Feike A. (2020), Plant uptake of nitrogen and phosphorus among grassland species affected by drought along a soil phosphorus gradient, in Plant and Soil, 48, 121-132.
Mineral-Associated Soil Carbon is Resistant to Drought but Sensitive to Legumes and Microbial Biomass in an Australian Grassland
Canarini Alberto, Mariotte Pierre, Ingram Lachlan, Merchant Andrew, Dijkstra Feike A. (2018), Mineral-Associated Soil Carbon is Resistant to Drought but Sensitive to Legumes and Microbial Biomass in an Australian Grassland, in Ecosystems, 21(2), 349-359.
Stoichiometric N:P flexibility and mycorrhizal symbiosis favour plant resistance against drought
Mariotte Pierre, Canarini Alberto, Dijkstra Feike A. (2017), Stoichiometric N:P flexibility and mycorrhizal symbiosis favour plant resistance against drought, in Journal of Ecology, 105(4), 958-967.
Soil microbial community resistance to drought and links to C stabilization in an Australian grassland
Canarini Alberto, Carillo Yolima, Mariotte Pierre, Ingram Lachlan, Dijkstra Feike (2016), Soil microbial community resistance to drought and links to C stabilization in an Australian grassland, in Soil Biology & Biochemistry, (103), 171-180.
Mineral associated soil carbon is resistant to drought but sensitive to legumes and microbial biomass in an Australian grassland
Canarini Alberto, Mariotte Pierre, Dijkstra Feike A., Mineral associated soil carbon is resistant to drought but sensitive to legumes and microbial biomass in an Australian grassland, in Ecosystems.
Stoichiometric N:P flexibility and mycorrhizal symbiosis favor plant resistance against drought
Mariotte Pierre, Canarini Alberto, Dijkstra Feike A., Stoichiometric N:P flexibility and mycorrhizal symbiosis favor plant resistance against drought, in Journal of Ecology.

Collaboration

Group / person Country
Types of collaboration
Western Sydney University - Hawkesbury Institute Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Weekly Meeting of the Hawkesbury Institute Individual talk Mediating drought effects in grasslands : importance of plant-soil interactions 16.09.2015 Richmond, NW, Australia Mariotte Pierre;
Rhizosphere 4, Stretching the Interface of Life Talk given at a conference Role of mycorrhizas in plant N:P stoichiometry under drought in Australian grasslands 21.06.2015 Maastricht, Netherlands Mariotte Pierre;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Changements climatiques : l’écologie au service de l’agriculture Performances, exhibitions (e.g. for education institutions) 12.10.2015 The International French School of Sydney, Sydney, NSW, Australia Mariotte Pierre;


Abstract

The global climate is changing dramatically due to anthropogenic greenhouse gas emissions. In South-Australia, a trend of prolonged periods without rain, alternated with increasing rainfall intensity, has already emerged during the last 50 years and is likely to continue during this century. More extreme rainfall patterns affect plant growth, which can lead to an increase in fire frequency and intensity. Drought and fire impact on the relative supply of nitrogen (N) and phosphorus (P) to plants and microbes with contrasting effects depending on soils types. Because plants and microbes have limited flexibility to take up N and P under conditions of unbalanced supply, drought and fire affecting N:P stoichiometry can have large impacts on primary productivity, plant community structure and carbon sequestration. However, nothing is really known about the impacts of drought and fire on plant and microbes competition for nutrients in grasslands. By using field and glasshouse experiments, this project aim at assessing limitation of soil N and P for plant growth and microbes under climate change (drought and fire), depending on rainfall variability and soil properties in Australian grasslands. Isotopes tracers (15N, 32P) will be used to determine the uptake of nitrogen and phosphorus by plants and microbes under drought and fire. Moreover, several ecosystem functions will be measured, such as litter decomposition, soil respiration and plant productivity, in order to related changes in soil N:P stoichiometry, plant and microbes uptakes and grassland functioning and sustainability. Collected data will be then integrated into a model to determine how independent fluxes of N and P affect the relationships between soil available, plant and microbial N:P ratios under conditions of drought and fire. Because climate change can dramatically alter the relative availability of N and P, incorporating stoichiometric constraints into models is critical in predicting ecosystem responses to climate change, specifically to drought and fire that have perhaps some of the largest impacts on reshaping the Australian landscape. This project will identify important mechanisms and provide tools to improve predictions about drought and fire impacts on plant productivity but also on soil nutrient availability, that will have important implications for grassland management.
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