Search results for " CYCLING"

Shifts in microbial diversity through land use intensity as drivers of carbon mineralization in soil

2015

10 pages; International audience; Land use practices alter the biomass and structure of soil microbial communities. However, the impact of land management intensity on soil microbial diversity (i.e. richness and evenness) and consequences for functioning is still poorly understood. Here, we addressed this question by coupling molecular characterization of microbial diversity with measurements of carbon (C) mineralization in soils obtained from three locations across Europe, each representing a gradient of land management intensity under different soil and environmental conditions. Bacterial and fungal diversity were characterized by high throughput sequencing of ribosomal genes. Carbon cycl…

Thermal and pressure-induced spin crossover in a novel three-dimensional Hoffman-like clathrate complex

2011

The synthesis and crystal structure of the interpenetrated metal–organic framework material Fe(bpac)2[Ag(CN)2]2 (bpac = 4,4′-bis(pyridyl)acetylene) are reported along with the characterization of its spin crossover properties by variable temperature magnetometry and Mossbauer spectroscopy. The complex presents an incomplete stepped spin transition as a function of temperature that is modified upon successive thermal cycling. The pressure-induced transition has also been investigated by means of high pressure Raman spectroscopy using a diamond anvil cell. The results show that it is possible to reach the thermally-inaccessible fully low spin state at room temperature by applying hydrostatic …

Effects of ions on water structure: a low-field (1) H T1 NMR relaxometry approach

2014

Aqueous salt solutions play an important role in nature because of their effects on environmental biogeochemical processes and on structural properties of biomolecules. Upon dissolution, salts split in ions that are solvated. Water in hydration shells is subjected to molecular motions that can be monitored by (1) H T1 NMR relaxometry. This technique allowed the evaluation of the nature of the interactions between water and ions via variable temperature experiments. Examination of relaxometry properties of aqueous solutions at variable salt concentrations allowed acknowledgement of the role played by ions in either structuring or destructuring water aggregates. A mathematical model has been …

Influence of a new bicycle crank design on aerobic parameters of non-cyclists

2012

Determinants of the distribution of nitrogen-cycling microbial communities at the landscape-scale

2010

Little information is available regarding the landscape-scale distribution of microbial communities and its environmental determinants. However, a landscape perspective is needed to understand the relative importance of local and regional factors and land management for the microbial communities. In this manuscript, we investigated the distribution of functional microbial communities involved in N-cycling and of the total bacterial and crenarchaeal communities over 107 sites using a grid with a 16 km lag distance within Burgundy, a 31 500 km2 region in France. After quantifying the abundances of the total bacterial, crenarchaeal, nitrate-reducing, denitrifying and ammonia-oxidizing communit…

Caractérisation des communautés microbiennes dans les technosols construits pour la restauration des friches industrielles

2012

Increasing soil degradation and its consequences on overall ecosystem services urge for restoration strategies. Construction of Technosols through assemblage of treated soil and industrial wastes is an innovative technology for the restoration of polluted land and re-use of industrial by-products. Recent studies have evidenced that Technosols could support ecosystemic services such as primary production but the knowledge about other soil functions, such as biogeochemical cycling, is limited. Due to the significant contribution of microbial communities to soil functioning, this PhD work was carried out to study the effect of the type of Technosol on microbial communities with a focus on func…

Loss in microbial diversity affects nitrogen cycling in soil

2013

International audience; Microbial communities have a central role in ecosystem processes by driving the Earth's biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. Here, we experimentally manipulated the soil microbial community using a dilution approach to analyze the functional consequences of diversity loss. A trait-centered approach was embraced using the denitrifiers as model guild due to their role in nitrogen cycling, a major ecosystem service. How various diversity metrics related to richness, eveness and phylogenetic diversity of the soil denitrifier community were affected by the removal experiment was assessed by 454 s…

Synchronie entre l'offre et la demande dans le cycle des nutriments: apprendre des écosystèmes naturels pour construire des agrosystèmes durables

2023

Redesigning agrosystems with more ecological regulations can help feed a growing population, preserve soils for future productivity and reduce environmental impacts. However, guidelines for redesigning agrosystems from natural systems are limited. Reviewing the last knowledge of ecosystem functioning, we outlined four ecological systems synchronizing the supply of soluble nutrients by soil biota to fluctuating plant nutrient demand. This synchrony limits deficiencies and excesses of soluble nutrient, which usually penalize both production and regulating services of agrosystems such as nutrient retention and soil carbon storage. We detail how ecological systems promoting synchrony can be ins…

Legacy effects of contrasting water and N-availability patterns on plantmicrobial response to rewetting

2019

National audience; Introduction. Shifts in the frequency and magnitude of rain events (precipitation regime) associated with climate change may affect plant morphological and physiological strategies as well as soil microbial activity.Objectives. The objective of this study was to determine i) how precipitation history shapes the response dynamics of soil bacterial and fungal communities to rewetting, as well as plant-microbial competition for N, and ii) how the N status of the system may modulate the effect of precipitation regime.Materials & methods. The legacy effects of 12 weeks of contrasting precipitation (frequent or infrequent watering, equal total water input) and N inputs was asse…

Soil carbon dynamics and nutrient cycling

2015

Chapitre 7 Section 2 SPE EcolDur; The quantity of organic carbon in soil and the quantity and type of organic inputs have profound impacts on the dynamics of nutrients. Soil organic matter itself represents a large reservoir of nutrients that are released gradually through the action of soil fauna and microorganisms: this is especially important for the supply of N, P and S to plants, whether agricultural crops or natural vegetation. Organic matter also modifies the behaviour and availability of nutrients through a range of mechanisms including increasing the cation exchange capacity of soil, thus leading to greater retention of positively charged nutrient ions such as Ca, Mg, K, Fe, Zn and…