Stéphane Bazot

Université Paris-Saclay · Life Sciences

It was time to take stock. We modified the humipedons classification key published in 2018, to make it easier and more practical. This morpho-functional taxonomy of the topsoil (humipedon) was only available in English: we also translated it into French and Italian. A standardized morpho-functional classification of humipedon (roughly the top 30-40...

Climate change is imposing drier atmospheric and edaphic conditions on temperate forests. Here, we investigated how deep soil (down to 300 cm) water extraction contributed to the provision of water in the Fontainebleau-Barbeau temperate oak forest over two years, including the 2018 record drought. Deep water provision was key to sustain canopy tran...

Characterizing the phenotypic and genetic variation among populations of crop wild relatives help understanding the ecological and evolutionary processes involved in population divergence, and better harness their diversity to mitigate the impact of climate change on crops. We assessed genetic and phenotypic diversity of the European crabapple, Mal...

Background and aims: Studying the relationship between phenotypic and genetic variation in populations distributed across environmental gradients can help us understand the ecological and evolutionary processes involved in population divergence. We investigated the patterns of genetic and phenotypic diversity in the European crabapple, Malus sylve...

We quantified the distribution of nitrogen (N), dry-matter (biomass) and of soil-applied 15 N in tree and soil compartments in five naturally-growing 20-year-old oak trees. After applying 15 N solution to soil at the base of the trees in spring, all the trees were felled in the fall, their root system excavated, biomass, nitrogen and 15 N content m...

It was time to take stock. We modified the humipedon classification key published in 2018 to make it easier and more practical. This morpho-functional taxonomy of the topsoil (humipedon) was only available in English; we also translated it into French and Italian. A standardized morpho-functional classification of humipedons (roughly the top 30–40...

Climate change is imposing drier atmospheric and edaphic conditions on temperate forests. Here, we investigated how deep soil (down to 300 cm) water extraction contributed to the provision of water in the Fontainebleau-Barbeau temperate oak forest over two years, including the 2018 record drought. Deep water provision was key to sustain canopy tran...

Key message The physical and chemical properties of soil are not a determinant of oak decline. Under stress, trees keep their vital activities by changing their physiological performance. Abstract The phenomenon of oak decline has been reported widely in various regions in the world. Although, many studies have addressed this problem, further stud...

WEBINAR: https://unipd.zoom.us/j/5745799331 TITLE: SOIL BIODIVERSITY AND MANAGEMENT - Practical tools and actions for facing the future JUNE 24th 14h30-16h30 1. Topsoil classification QUESTION: Is there a wise way to use the soil? 15h30 - 16h30 GENERAL DISCUSSION JUNE 25th 14h00-15h00 2. 2.1. Soil and biodiversity QUESTION: Is soil biodiversity...

AimsWe simultaneously quantified the fate of soil absorbed mineral nitrogen in different tree compartments along with nitrogen immobilization by microorganisms during spring in 20-year-old oak trees.MethodsA soil-applied 15N solution was traced in situ into the fine roots, medium roots, xylem, phloem, branches, leaves, extractable soil, and microbi...

Although ongoing research has revealed some of the main drivers behind global spatial patterns of microbial communities, spatio-temporal dynamics of these communities still remain largely unexplored. Here we investigate spatio-temporal variability of both bacterial and eukaryotic soil microbial communities at local and intercontinental scales. We c...

Although petroleum plays an important part in world economy, its exploitation can bring about a great deal of contamination in soil. To select the tree species being tolerant to soil pollution, a pot experiment has been carried out to assess and compare the growth potential of the seedlings of black locust (Robinia pseudoacacia L.), Chinaberry (Mel...

Livestock are a threat to forest regeneration. Moreover, soil quality and fertility is degraded under their hooves. Livestock grazing in natural forests of the Zagros Mountains, in western Iran, create or maintain temporal or permanent transit paths through valuable oak stands. We surveyed the physical, chemical, and biological characteristics of t...

Forest soils store important amounts of carbon, largely in the form of soil organic matter (SOM). The fate and residence time of this carbon in the soil is partially controlled by microorganisms, which metabolize and emit this carbon as CO2, an important greenhouse gas. Forest stand density, due to the variation in organic matter inputs (leaf litte...

Functional studies of tree decline have mainly focused on process inside the plant showing possible alterations of carbon transport, storage and hydraulic functions. However, the processes occurring at the plant-soil interface have been seldom investigated. Our objective is to examine carbon functional alterations in the belowground compartment in...

What is soil? The soil is a natural system playing the role of an active interface between organisms and mineral substrates in larger ecosystems. Ecosystems are numerous and diverse. Substrates too are difficult to classify as basis for soil formation and habitat provision. The Applied Soil Ecology journal decided to dedicate three special issues t...

Functional studies of tree decline have mainly focused on process inside the plant showing possible alterations of carbon transport, storage and hydraulic functions. However, the processes occurring at the plant-soil interface have been seldom investigated. Our objective is to examine carbon functional alterations in the belowground compartment in...

This article illustrates a short training course for students at the Master's level, which explores relationships between plants and soil. It takes place in the Forest of Fontainebleau (France), where a reception centre with a large room (30 m2) is located containing a Berlese equipment, and many microscopes. On the first day, students are accompan...

The origin of N which contributes to the synthesis of N reserves of in situ forest trees in autumn and to the growth of new organs the following spring is currently poorly documented. To characterize the metabolism of various possible N sources (plant N and soil N), six distinct 20-year-old sessile oaks were 15N labelled by spraying 15NH415NO3: (i)...

The origin of the N which contributes to the synthesis of N reserves of in situ forest trees in autumn, and to the growth of new organs the following spring, is currently poorly documented. To characterize the metabolism of various possible N sources (plant N and soil N), six distinct 20 year-old sessile oaks were 15N labelled by spraying 15NH415NO...

Keymessage Under non-extreme drought conditions, reduced stem growth is not associated with reserve or hydraulic impairment in beech suffering from long-term decline. Abstract Global change is expected to increase the frequency and the intensity of drought events in temperate ecosystems. In some regions, this might be associated with an increase i...

Key message. We demonstrate that, beyond leaf phenology, the phenological cycles of wood and fine roots present clear responses to environmental drivers in temperate and boreal trees. These drivers should be included in terrestrial ecosystem models. Context. In temperate and boreal trees, a dormancy period prevents organ development during adverse...

Forest productivity declines with tree age. This decline may be due to changes in metabolic functions, resource availability and/or changes in resource allocation (between growth, reproduction and storage) with tree age. Carbon and nitrogen remobilization/storage processes are key to tree growth and survival. However, studies of the effects of tree...

The distribution of nitrogen (N) and carbon (C) pools in 100-year-old sessile oaks was investigated in situ at four key periods of tree phenology. Leaves, twigs, trunk and roots were sampled, and total non-structural nitrogen compounds (TNNC) and total non-structural carbohydrates (TNC) were quantified. TNC concentrations decreased more than 50 % b...

The ongoing climate change is altering the precipitation patterns (abundance and frequency) of most parts of the world. The consequences of these changes on forests are already visible through frequent declines. A lot of them can be linked to the occurrence of long and/or repeated drought periods. Although forest decline could severely impact the n...

Forest productivity plays an important role in wood production and forest carbon storage capacity. It is well known that forest productivity declines with tree age (Genet et al., 2009). This decline could result from a carbon assimilation decrease and/or a modification of carbon allocation (Ryan et al., 2006 ; Genet, 2009). Relationships between tr...

Soil CO2 efflux is the main source of CO2 from forest ecosystems and it is tightly coupled to the transfer of recent photosynthetic assimilates belowground and their metabolism in roots, mycorrhiza and rhizosphere microorganisms feeding on root-derived exudates. The objectives of our study were to assess patterns of belowground carbon allocation am...

Soil CO2 efflux is the main source of CO2 from forest ecosystems and it is tightly coupled to the transfer of recent photosynthetic assimilates belowground and their metabolism in roots, mycorrhiza and rhizosphere microorganisms feeding on root-derived exudates. The objectives of our study were to assess patterns of belowground carbon allocation am...

This work intended to study the relationship between diuron herbicide dissipation and the population dynamics of co-cultivated Delftia acidovorans WDL34 (WDL34) and Arthrobacter sp. N4 (N4) for different cell formulations: free cells or immobilization in Ca-alginate beads of one or both strains. GFP-tagged WDL34 and N4 Gram staining allowed analyzi...

Trunk CO2 efflux is a major component of total CO2 forest ecosystem efflux but its determinism is still poorly understood. This CO2 flux could originate from different carbon sources (respiration of newly assimilates or reserves; xylem sap flow dissolved CO2). These potential CO2 sources of the ecosystem vary at a diurnal and seasonal time scale. T...

Bioaugmentation-assisted phytoextraction may enhance the phytoextraction efficiency thanks to larger metal mobilization by microbial metabolites. Green fluorescent protein-tagged cells of Pseudomonas aeruginosa, Pseudomonas fluorescens or Ralstonia metallidurans, able to produce siderophores, were inoculated in an agricultural soil containing Cr (4...

The effects of elevated CO2 concentration upon rhizodeposition of nitrogen were investigated on field-grown Lolium perenne planted in soil cores set into the resident soil of a intensively managed ryegrass sward treated with elevated CO2 for nine consecutive years, under two contrasted N fertilisation regimes (Swiss FACE Experiment). The planted co...

A bacterial consortium able to mineralize two herbicides, glyphosate (Pseudomonas 4ASW) and diuron (Arthrobacter sp. N4 and Delftia acidovorans), was cultivated in both a synthetic culture medium without phosphate and a sediment extract medium. In the aim at optimizing glyphosate and diuron mineralization, all the combinations, i.e., free and/or im...

Mineralization of diuron has not been previously demonstrated despite the availability of some bacteria to degrade diuron into 3,4-dichloroaniline (3,4-DCA) and others that can mineralize 3,4-DCA. A bacterial co-culture of Arthrobacter sp. N4 and Delftia acidovorans W34, which respectively degraded diuron (20 mg l(-1)) to 3,4-DCA and mineralized 3,...

The effects of enriched CO2 atmosphere on partitioning of recently assimilated carbon were investigated in a plant-soil-microorganism system in which Lolium perenne seedlings were planted into cores inserted into the resident soil within a sward that had been treated with elevated CO2 for 9 consecutive years, under two N fertilisation levels (Swiss...

1It is hypothesized that defoliation-induced changes in plant carbon allocation and root soluble C concentration modify rhizosphere C availability and, further, the abundance and activity of soil microbes and their grazers. To test this hypothesis, field-grown Lolium perenne swards were defoliated twice during their second growing season at two nit...

The aim of our work was to study C fluxes in plant and to rhizosphere of Lolium perenne in order to explain the relation between plant functioning and rhizodeposition. In a first part, we have determined the contribution of recently assimilated carbon to rhizodeposition. We have developed a double long-term labelling of plants shoots (14CO2 and 13C...

L'objectif de notre travail a été étudié le transfert de C dans la plante et vers la rhizosphère de Lolium perenne afin d'expliciter le couplage entre le fonctionnement de la plante et la rhizodéposition. Nous avons d'abord déterminé la contribution du carbone récemment assimilé par la plante à la rhizodéposition. Nous avons ainsi réalisé un double...

Summary • Risk assessment studies of transgenic crops have recently brought evidence of a low spontaneous hybridization frequency of Brassica napus with Raphanus raphanistrum. The fate of the first generation hybrids is crucial to determine the initial rate of spread of transgenes. • This work aims to compare the fitness components of parents and F...