Pierre Mariotte

Pierre Mariotte
Agroscope · Grazing Systems

PhD, Ecole Polytechnique Fédérale de Lausanne

About

87
Publications
21,222
Reads
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1,576
Citations
Additional affiliations
June 2019 - present
Agroscope
Position
  • Deputy Head - Scientific Collaborator
February 2017 - June 2019
École Polytechnique Fédérale de Lausanne
Position
  • Teacher and Course Organiser
Description
  • Essentials of Ecology (speciation, biodiversity, biotic interactions, community structure, species co-existence, plant-soil interactions, biodiversity-ecosystem functioning, land-use change, climate change and ecosystem functioning) - Bachelor Year 2
January 2017 - present
Ecology and Evolution
Position
  • Associate Editor
Description
  • http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2045-7758
Education
June 2008 - June 2012
École Polytechnique Fédérale de Lausanne
Field of study
  • Plant and Soil Community Ecology
September 2006 - June 2008
University of Franche-Comté
Field of study
  • Ecology
September 2003 - June 2006
University of Franche-Comté
Field of study
  • Biology-Ecology

Publications

Publications (87)
Article
While dominant species are considered to be the main determinant of ecosystem properties because of the large amount of biomass they produce, recent studies suggest that subordinates can also be of great importance. However, findings on the functional role of subordinate species are still scarce and this seems largely due to the lack of knowledge a...
Article
1.The subordinate insurance hypothesis suggests that highly diverse communities contain greater numbers of subordinate species than less diverse communities. It has previously been reported that subordinate species can improve grassland productivity during drought, but the underlying mechanisms remain undetermined. 2.Using a combination of subordi...
Presentation
Stoichiometric homeostasis represents the ability of an organism to maintain constant chemical elements despite variations in the environment and is a powerful mechanism involved in the maintenance of ecosystem functioning, especially under climate change. For example, drought directly increases soil N:P ratio, and consequently influences plant N:P...
Article
1. According to the insurance hypothesis, more diverse plant communities have higher probability to be more resistant to drought. While many experiments have been carried out to determine the effects of plant diversity on plant community insurance, the results are still contradictory. 2. Here, we conducted a drought experiment where we tested if t...
Article
Plant effects on soil biota can result in feedbacks affecting plant performance, with consequences for plant community and ecosystem dynamics on short and long time-scales. In addition, the strength and direction of plant–soil feedbacks depend on temporal shifts in abiotic environmental conditions. We synthesize current knowledge on temporal aspec...
Article
Full-text available
Climate warming is releasing carbon from soils around the world ¹⁻³ , constituting a positive climate feedback. Warming is also causing species to expand their ranges into new ecosystems ⁴⁻⁹ . Yet, in most ecosystems, whether range expanding species will amplify or buffer expected soil carbon loss is unknown ¹⁰ . Here we used two whole-community tr...
Article
In Europe, the conservation of extensively grazed semi-natural grasslands is addressed by agricultural policies whose effectiveness is questioned. We studied sub-xerophilous Bromus erectus semi-natural grasslands to analyse the interactions among: i) agri-environmental payments, ii) grazing regimes, iii) environmental conditions, iv) habitat conser...
Article
Full-text available
Alnus viridis is a pioneer species that has expanded in Central Europe in the last decades, causing a series of negative agro-environmental impacts. Robust livestock grazing could be used as a targeted tool to reduce its encroachment, but more information is needed to find the best approach to achieve this goal. In this study, we assessed the poten...
Article
Full-text available
The increase in severity of droughts associated with greater mortality and reduced vegetation growth is one of the main threats to tropical forests. Drought resilience of tropical forests is affected by multiple biotic and abiotic factors varying at differ- ent scales. Identifying those factors can help understanding the resilience to ongoing and f...
Preprint
Climate warming is releasing carbon from soils around the world 1–3 , constituting a positive climate feedback. Warming is also causing species to expand their ranges into new ecosystems 4–9 . Yet, in most ecosystems, whether range expanding species will amplify or buffer expected soil carbon loss is unknown ¹⁰ . Here we used alpine grasslands as a...
Preprint
Full-text available
The increase in severity of droughts associated with greater mortality and reduced vegetation growth is one of the main threats to tropical forests. Drought resilience of tropical forests is affected by multiple biotic and abiotic factors varying at different scales. Identifying those factors can help understanding the resilience to ongoing and fut...
Article
Full-text available
Extreme drought decreases aboveground net primary production (ANPP) in most grasslands, but the magnitude of ANPP reductions varies especially in C3-dominated grasslands. Because the mechanisms underlying such differential ecosystem responses to drought are not well-resolved, we experimentally imposed an extreme 4-year drought (2015-2018) in two C3...
Article
Full-text available
Aims Previous cover crop studies mainly focused on the links between plant uptake and soil fertility, and there is a clear knowledge gap regarding the role of microbes in these processes. Our aim was then to better understand the effects of plant mixtures (versus monoculture) and the specific effects of each plant species on nitrogen (N) and phosph...
Article
Full-text available
Green alder (Alnus viridis) is a shrub species that has expanded over former pastures in Central Europe due to land abandonment, leading to negative agri-environmental impacts, such as a reduction in forage yield and quality and an increase in nitrate leaching. Robust livestock breeds such as Highland cattle could be used to control A. viridis encr...
Article
Full-text available
Aims Functional group composition of a plant community is mainly driven by environmental factors and is one of the main determinants of grassland biodiversity and productivity. Therefore, it is important to understand the role of plant functional groups (PFGs) in mediating the impact of environmental conditions on ecosystem functions and biodiversi...
Article
Droughts have increased in frequency, duration, and severity across most of the tropics but their effect on forest communities remain not fully understood. Here we assessed the effects of a severe El Niño-induced drought event on dominant and lowabundance understory plant species and the consequent impacts on ecosystemfunc- tions in the South Ameri...
Article
Full-text available
Understanding the agroecological mechanisms that determine forage yield and quality in intensively managed permanent grasslands is crucial to optimize management and provide environmental and economic benefits to society. In this study, we assessed the relative contribution of climatic, soil and vegetation drivers on forage yield and quality in nin...
Poster
Full-text available
Green alder (Alnus viridis, Chaix) is a pioneer shrub species that has expanded over former pastures in Central Europe due to land abandonment, leading to a reduction in biodiversity and an increase in nitrate leaching and soil acidification. This project aims 1) to study the spatial distribution of Highland cows in green alder-encroached pastures...
Article
En Suisse, où les herbages occupent 70% des surfaces agricoles utiles avec une production laitière presque exclusivement dépendante de la production fourragère indigène, les changements climatiques actuels et à venir représentent une menace majeure pour l'économie agricole. Des recherches sur les prairies permanentes de Suisse romande, exploitées d...
Article
Global change alters how terrestrial ecosystems function and makes them less stable over time. Global change can also suppress the development and effectiveness of arbuscular mycorrhizal fungi (AMF). This is concerning, as AMF have been shown to alleviate the negative influence of global changes on plant growth and maintain species coexistence. How...
Article
Full-text available
Aims Here we assessed N and P uptake of four grassland species grown together in response to a short-term drought event along a soil P gradient. Methods We used ¹⁵N and ³²P tracers to examine uptake of N and P by the grasses Bothriochloa macra, Themeda triandra, Lolium perenne and Microlaena stipoides grown together in pots with initial available...
Article
Full-text available
Groundwater level is crucial for wetland plant growth and reproduction, but the extent of its effect on plant growth can vary along with changed precipitation and temperature at different seasons. In this context, we investigated the effect of two groundwater levels (10 cm vs. 20 cm depth) on growth and reproductive parameters of Carex cinerascens,...
Article
Full-text available
Grazing-induced changes in plant community structure can be altered by the biogeochemical regime of the ecosystem. However, responses of community structure (e.g., changes in biomass, canopy height, and stand density) to grazing-induced changes in foliar nutrient content—whether species-specific or species group-specific (dominant vs. subordinate)—...
Article
Drought events can strongly affect ecosystem functioning by modifying relationship between plants, microbes and soil chemistry, with consequent impacts on nutrient cycling. However, the potential impacts of a soil moisture reduction on the nitrogen (N) and phosphorus (P) cycling in grasslands remain poorly understood, especially in regard to forage...
Article
Full-text available
Drought can occur at different times during the grassland growing season, likely having contrasting effects on forage production when happening early or later in the season. However, knowledge about the interacting effects of the timing of drought and the development stage of the vegetation during the growing season is still scarce, thus limiting o...
Article
Plants and microbes release a plethora of volatiles that act as signals in plant‐microbe interactions. Characterizing soil's volatilome and microbiome might shed light on the nature of relevant volatile signals and on their emitters. This hypothesis was tested by characterizing plant cover, soil's volatilome, nutrient content and microbiomes in thr...
Article
Severe constraints on grasslands productivity, ecosystem functions, goods and services are expected to result from projected warming and drought scenarios under climate change. Negative effects on vegetation can be mediated via soil fertility and water holding capacity, though specific mechanisms are fairly complex to generalise. In field drought e...
Chapter
Full-text available
Evidence is accumulating that belowground soil organisms are strong drivers of the aboveground plant community. In this chapter, we examine how soil communities influence plant community assembly through priority effects, soil legacy effects, and niche modification. We discuss how different functional groups of soil organisms drive competitive inte...
Data
Here is the video podcast explaining the findings of the paper. You can download the video below and also have a look at the post on the Journal of Ecology Blog: https://jecologyblog.wordpress.com/2018/06/15/harper-prize-highly-commended-papers-2017-plant-soil-interactions-part-2
Article
Full-text available
Sandy coastal plant communities in tropical regions have been historically under strong anthropic pressure. In Brazil, these systems shelter communities with highly plastic plant species. However, the potential of these systems to regenerate without human assistance after disturbances has hardly been examined. We determined the natural regeneration...
Article
Full-text available
Drought is predicted to increase in many areas of the world with consequences for soil carbon (C) dynamics. Plant litter, root exudates and microbial biomass can be used as C substrates to form organo-mineral complexes. Drought effects on plants and microbes could potentially compromise these relative stable soil C pools, by reducing plant C inputs...
Article
Full-text available
A rainfall manipulation experiment was conducted over a two-year period on two semi-natural grassland sites, in order to determine the effects of drought on both forage production (dry matter and nutritive value) and plant-soil relationships. Water stress simulations were performed with the aid of rainout shelters. Among the nutritional parameters,...
Article
In agricultural and natural systems researchers have demonstrated large effects of plant-soil feedback (PSF) on plant growth. However, the concepts and approaches used in these two types of systems have developed, for the most part, independently. Here, we present a conceptual framework that integrates knowledge and approaches from these two contra...
Article
Full-text available
Ecosystems are increasingly prone to climate extremes, such as drought, with long lasting effects on both plant and soil communities and, subsequently, on carbon (C) cycling. However, recent studies underlined the strong variability in ecosystem's response to droughts, raising the issue of non-linear responses in plant and soil communities. The con...
Article
Break crops are used in agriculture to reduce soil pathogens and improve yield of subsequent cereal crops. However, they can also affect soil microbial communities beneficial to plant growth including arbuscular mycorrhizal fungi (AMF). Two wheat genotypes (IAW2013 and 249) were planted after crop rotation with canola or chickpea with different nit...
Article
1. Drought induces changes in the nitrogen (N) and phosphorus (P) cycle but most plant species have limited flexibility to take up nutrients under such variable or unbalanced N and P availability. Both the degree of flexibility in plant N:P ratio and of root symbiosis with arbuscular mycorrhizal (AM) fungi might control plant resistance to drought-...
Article
Successful colonization by invasive species depends on both the ability to disperse seeds to a site and an ability to establish once seeds have arrived. While seed and establishment limitation are known to jointly influence colonization, decomposing establishment limitation into density-dependent and density-independent components has remained chal...
Article
Californian grasslands have a long history of invasion, starting with the introduction of exotic forage species a century ago, and followed by newer waves of invaders. Both exotic and invasive species produce large amounts of litter, but the importance of litter accumulation on the growth and expansion of these species has not been rigorously asses...
Article
Drought is predicted to increase in many areas of the world, which can greatly influence soil microbial community structure and C stabilization. Increasing soil carbon (C) stabilization is an important strategy to mitigate climate change effects, but the underlying processes promoting C stabilization are still unclear. Microbes are an important con...
Article
Full-text available
Neotropical rainforests are global biodiversity hotspots and are challenging to restore. A core part of this challenge is the very long recovery trajectory of the system: recovery of structure can take 20–190 years, species composition 60–500 years, and reestablishment of rare/endemic species thousands of years. Passive recovery may be fraught with...
Presentation
Drought periods are expected to increase over the next decades putting the sustainability of forage production at stake. Beside direct water stress effects on plant survival and growth, soil moisture reduction also affects plant mineral nutrition by reducing N and P uptake and mobility. These drought induced-changes in soil nutrient availability gr...
Article
Loss of plant diversity resulting from forecasted drought events is likely to alter soil functioning and affect earthworm communities. Plant-soil interactions are expected to play an important role in mediating climate change effects on soil decomposers. In this study, we test above-belowground linkages after drought by focusing on the effects of s...
Article
Subordinate species composition and distribution are regarded as a result of the dominant species structure. However, the spatial organization of subordinate species can also be related to dispersal abilities and interactions (competition and facilitation) within subordinate species. Here, we tested the influence of dominant species on subordinate...
Article
Full-text available
Plant invasions are a threat to rangelands in California. Understanding how seeds of invasive plants are dispersed is critical to developing sound management plans. Domestic livestock can transport seeds long distances by ingesting and passing seeds in dung (endozoochory), or by the attachment of seeds to skin and fur (epizoochory). Our objective w...
Article
QuestionA better understanding of the response of Sphagnum mosses and associated vascular plants to climate warming is relevant for predicting the carbon balance of peatlands in a warmer world. Open-top chambers (OTCs) have been used to investigate the effect on soil biogeochemical processes in peatlands, but little information is available on the...
Poster
Full-text available
Background/Question/Methods Rainfall is a key control on production and composition in California grasslands. While less studied, precipitation may also have a lagged effect, with previous year’s rainfall affecting composition the following year. Here, we ask how different functional groups respond to current and lagged effects of precipitation in...
Presentation
Background/Question/Methods The occurrence of alternative states and thresholds has become a central issue in Ecology and alternate states represent major shifts in ecosystem function due to changes in abundance and composition of dominant species. This particularly occurs in species invasion with thesholds, which lead to invasion when the invasive...
Presentation
Background/Question/Methods Spatial variation in biotic and abiotic filters can promote coexistence and limit competitive exclusion by allowing species to increase when rare on some parts of the landscape. Covariance between the environment and intraspecific competition leads to stronger competition between conspecifics in favorable locations than...
Data
Summary Grasslands cover ˜30% of the Earth's terrestrial surface and provide many ecosystem services. Many grasslands are heavily managed to maximize these services for human benefit, but the outcome of management is anticipated to be increasingly influenced by various aspects of climate change and elevated atmospheric CO2. The relative importance...
Article
1. Grasslands cover ~30% of the Earth’s terrestrial surface and provide many ecosystem services. Many grasslands are heavily managed to maximize these services for human benefit, but the outcome of management is anticipated to be increasingly influenced by various aspects of climate change and elevated atmospheric CO2. The relative importance of gl...
Book
Full-text available
Grasslands cover around 30% of the Earth's terrestrial surface and provide important ecosystem services. On the other hand, grasslands are among the most endangered ecosystems, threatened by land-use change, mainly through agricultural intensification or abandonment, and ongoing climatic changes, such as warming and drought. The principal aim of th...
Presentation
Full-text available
According to the insurance hypothesis, more diverse plant communities are more likely to be resistant to drought. While many experiments have been carried out to determine the effects of plant diversity on community insurance, the results are still contradictory. Here, we conducted a drought experiment where we tested if the presence of subordinate...
Article
Changes in agricultural practices of semi-natural mountain grasslands are expected to modify plant community structure and shift dominance patterns. Using vegetation surveys of 11 sites in semi-natural grasslands of the Swiss Jura and Swiss and French Alps, we determined the relative contribution of dominant, subordinate and transient plant species...
Article
Full-text available
In grassland communities, plants can be classified as dominants or subordinates according to their relative abundances, but the factors controlling such distributions remain unclear. Here, we test whether the presence of the arbuscular mycorrhizal (AM) fungus Glomus intraradices affects the competitiveness of two dominant (Taraxacum officinale and...
Presentation
Full-text available
Background / Purpose: In the short term, plant effects on soil biota can result in feedbacks affecting plant performance, with consequences for plant community and ecosystem dynamics. Over longer time scales, the strength and direction of plant-soil feedbacks depend on temporal shifts in abiotic environmental conditions. Here, we synthesize current...
Presentation
Full-text available
Background/Question/Methods According to the insurance hypothesis, more diverse plant communities have higher probability to be more resistant to drought. While many experiments have been carried out to determine the effects of plant diversity on plant community insurance, the results are still contradictory. Here, we conducted a drought experiment...
Thesis
Full-text available
The relevance of biodiversity to human health is an increasing international political issue as it causes concern for ethical and aesthetic reasons, but also has a strong impact on ecosystem properties and ecological goods and services utilised by humanity. However, humans have applied increasing pressure on worldwide biodiversity through pollution...
Article
Full-text available
Background and aims - A large variety of methods are used by ecologists for studies at plant community level. While early works were mainly descriptive, more manipulative experiments are now being undertaken because they provide a better functional understanding and a greater insight into underlying mechanisms. Mathematical models are also being in...
Presentation
Full-text available
Malgré leur faible recouvrement dans la communauté végétale, les espèces subordonnées participent fortement à la biodiversité et pourraient avoir des effets très importants sur le fonctionnement de l’écosystème. Alors que la plupart des études ont concentré leur recherche sur les espèces dominantes, le but de notre étude consistait à tester le rôle...
Article
Questions: What is the importance of root competition in the competitive abilities of dominant and subordinate species? Location: Pairwise greenhouse experiment based on field data from a semi-natural grassland community in the Swiss Jura Mountains (Col du Marchairuz, Switzerland). Methods: The dominance hierarchy from a mountain wood-pasture ecos...