Résumé
Unlike Eucalyptus monocultures, nitrogen fixing trees are likely to improve the soil nutrient status through the decomposition of N-enriched litter. The Home Field Advantage (HFA) hypothesis states that plants can create conditions that increase the decomposition rates of their own litter. However, there may not be any HFA when most of the decomposers are generalists. A reciprocal transplant decomposition experiment of fine roots and leaves of Acacia mangium and Eucalyptus grandis was undertaken in monocultures of these two species to test the HFA hypothesis using a complete randomized design with three blocks. Three litterbags containing leaf or fine root residues of each species were collected every 3 months from each plot over 12 months for fine roots and 24 months for leaves. The litter mass and C, N and P concentrations were measured at each sampling date. The concentrations of C-compounds were measured 0, 12 and 24 months from the start of the experiment. There was no evidence of HFA for either the leaves or the fine roots of either species. The decomposition rates were slower for Acacia litter than for Eucalyptus litter even though initial N concentrations were 1.9–2.9 times higher and P concentrations were 1.5–3.3 times higher in the Acacia residues. N:P ratios were greater than 20–30 for the residues of both species, with the highest values for Acacia. Litter decomposition depended partly on the C quality of the litter, primarily in terms of water soluble compounds and lignin content. As shown recently in tropical rainforests, these results suggest that the activity of decomposers is limited by energy starvation in tropical planted forests. Decomposer activity may also have been limited by P availability which may not have been directly related to the P concentrations or C:P ratios in the residues. (Résumé d'auteur)
Auteurs, date et publication :
Auteurs J.-R. Bachega Feijo Rosa , J.-P. Bouillet , M. De Cassia Piccolo , L. Saint André , J.-M. Bouvet , Y. Nouvellon , J.-L. De Moraes Gonçalves , A. Robin , J.-P. Laclau
Publication : Forest Ecology and Management
Date : 2025
Volume : 359
Pages : 33-43
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
Abstract. The understanding of physical dynamics is crucial to
provide scientifically credible information on lake ecosystem management.
We show how the combination of in situ observations, remote sensing data, and
three-dimensional hydrodynamic (3D) numerical simulations is capable of
resolving various spatiotemporal scales involved in lake dynamics. This
combination is achieved through data assimilation (DA) and uncertainty
quantification. In this study, we develop a flexible framework by
incorporating DA into 3D hydrodynamic lake models. Using an ensemble Kalman
filter, our approach accounts for model and observational uncertainties. We
demonstrate the framework by assimilating in situ and satellite remote
sensing temperature data into a 3D hydrodynamic model of Lake Geneva.
Results show that DA effectively improves model performance over a broad
range of spatiotemporal scales and physical processes. Overall, temperature
errors have been reduced by 54 %. With a localization scheme, an ensemble
size of 20 members is found to be sufficient to derive covariance matrices
leading to satisfactory results. The entire framework has been developed
with the goal of near-real-time operational systems (e.g., integration into
meteolakes.ch).
Auteurs, date et publication :
Auteurs Theo Baracchini , Philip Y. Chu , Jonas Šukys , Gian Lieberherr , Stefan Wunderle , Alfred Wüest , Damien Bouffard
Publication : Geoscientific Model Development
Date : 2020
Volume : 13
Issue : 3
Pages : 1267-1284
Catégorie(s)
#INRAE #OLAAuteurs, date et publication :
Auteurs Robert Jandl , Mirco Rodeghiero , Cristina Martinez , M Francesca Cotrufo , Francesca Bampa , Bas van Wesemael , Robert B Harrison , Iraê Amaral Guerrini , Daniel deB Richter Jr , Lindsey Rustad , others
Publication : Science of the total environment
Date : 2025
Volume : 468
Pages : 376–383
Catégorie(s)
#ACBB #ACBB Lusignan #INRAEAuteurs, date et publication :
Auteurs Stéphan Jacquet , Onur Kerimoglu , Frédéric Rimet , Gérard Paolini , Orlane Anneville
Publication : Freshwater Biology
Date : 2025
Volume : 59
Issue : 12
Pages : 2472-2487
Catégorie(s)
#INRAE #OLARésumé
The antibodies of jawless vertebrates consist of leucine-rich repeat arrays encoded by somatically assembled VLRB genes. It is unknown how the incomplete germline VLRB loci are converted into functional antibody genes during B lymphocyte development in lampreys. In Lampetra planeri larvae lacking the cytidine deaminase CDA2 gene, VLRB assembly fails, whereas the T lineage-associated VLRA and VLRC antigen receptor gene assemblies occur normally. Thus, CDA2 acts in a B cell lineage-specific fashion to support the somatic diversification of VLRB antibody genes. CDA2 is closely related to activation-induced cytidine deaminase (AID), which is essential for the elaboration of immunoglobulin gene repertoires in jawed vertebrates. Our results thus identify a convergent mechanism of antigen receptor gene assembly and diversification that independently evolved in the two sister branches of vertebrates.
Auteurs, date et publication :
Auteurs Ryo Morimoto , Connor O’meara , Stephen Holland , Inês Trancoso , Ahmed Souissi , Michael Schorpp , Danièle Vassaux , Norimasa Iwanami , Orlando Giorgetti , Guillaume Evanno , Thomas Boehm
Publication : Science Immunology
Date : 2020
Volume : 5
Issue : 45
Pages : eaba0925
Catégorie(s)
#INRAE #PEARLRésumé
Pyrosequencing-based analysis of 16S rRNA gene sequences revealed a significant correlation between apatite dissolution and the abundance of betaproteobacteria on apatite surfaces, suggesting a role for the bacteria belonging to this phylum in mineral weathering. Notably, the cultivation-dependent approach demonstrated that the most efficient mineral-weathering bacteria belonged to the betaproteobacterial genus Burhkolderia.
Auteurs, date et publication :
Auteurs C. Lepleux , M. P. Turpault , P. Oger , P. Frey-Klett , S. Uroz
Publication : Applied and Environmental Microbiology
Date : 2012
Volume : 78
Issue : 19
Pages : 7114-7119
Catégorie(s)
#FORET Breuil #INRAERésumé
Climate change has swept away the former general principles of long-term stability in forest productivity. New types of models are needed to predict growth and to plan forest management under future climate conditions. These models must remain robust for silvicultural practices and variations in climate. In this study, we present a new type of model development to achieve these goals. Our study focused on pure and mixed stands of Quercus petraea and Pinus sylvestris in central France. We used National Forest Inventory (NFI) data: respectively, 525 and 548 pure plots of Quercus petraea and Pinus sylvestris, and 68 plots of mixed species. We also used 108 tree cores from an experimental site of the same species. The cores cover the period from 1971 to 2013, making a total of 4572 individual annual increments. We coupled two types of models. One was developed with NFI data (transversal data). This model takes into account mean diameter and stand density effects on stand growth. It includes a set of biophysical factors accounting for stand fertility. The other one was developed with the data from tree cores (longitudinal data), and provides a climate modulation thanks to the correlation between ring width and yearly climate. The model with tree core data reveals the influence of December to July rainfalls on yearly variability in stand growth for Quercus petraea and of May to August rainfalls for Pinus sylvestris. We obtained a coupled model that allowed us to project growth up to 2100 for all the different IPCC scenarios but one; the model was outside its area of validity beyond 2060 for the RCP 8.5 scenario.
Auteurs, date et publication :
Auteurs Patrick Vallet , Thomas Perot
Publication : Agricultural and Forest Meteorology
Date : 2018
Volume : 263
Pages : 258-266
Catégorie(s)
#FORET OPTMix #INRAERésumé
Calcium (Ca) is an essential macronutrient which plays a fundamental role in ecosystem structure and function. In temperate forest ecosystems, Ca oxalate is ubiquitous, existing in live and decomposing biomass pools. Calcium in minerals occurs principally as carbonate and silicate. Because of structural differences between its different forms, Ca speciation can influence the Ca biogeochemical cycle. In this study, we compared three beech temperate forests of contrasting soil Ca availability, i.e., dystric cambisol (DC), eutric cambisol, and rendzic leptosol (RL), but with similar climates, atmospheric depositions, species compositions and management. The pools and fluxes of total Ca (Cat) and Ca oxalate (Caox) were assessed in plant samples (aboveground and belowground tree tissues, forest floor). Pools and fluxes of Cat were also quantified in the atmospheric inputs (dry and wet deposits), in the soil (total and exchangeable fractions) and in the soil solutions at different depths. The soil solutions were measured monthly for 4 years to study the seasonal dynamics of Ca fluxes. A budget of dissolved Ca was also determined for the forest floor and soil layers. Regarding the global Ca cycle at the stand scale, our study highlighted: (i) the predominant role of biological recycling in the Ca cycle in forest ecosystems for all soil types; the turnover rates of fine roots and leaves were approximately 43 and 39% of the total Ca taken up by trees each year, revealing that only 18% accumulated in the perennial tissues; (ii) the vegetation was Ca-enriched in the high Ca soil (RL) compared to the low-Ca soil (DC); (iii) the existence of an unexpected available Ca source in DC due to upwelling by the diffusion of Ca issued from the dissolution of carbonates in-depth; (iv) a higher production of dissolved Ca (from carbonate dissolution) in RL compared to DC, resulting in an important loss of Ca by drainage (280 kg ha−1 year vs. 14 kg ha−1 year); (v) monthly measurements demonstrated that the seasonal dynamics was mainly linked to biological activity. In addition, our study showed that the distribution of Caox differs greatly between vegetation compartments, ranging from null (stem and branch wood) to up to 40% (stem and branch bark and fine roots) of the Cat in the biomass. Vegetation is a factory of Ca oxalate, and the return of this Caox enriched vegetation to the soil influences the Ca mobility in the forest floor, as demonstrated by a Caox residence time shorter than that of Cat in the DC.
Auteurs, date et publication :
Auteurs Marie-Pierre Turpault , Christophe Calvaruso , Marie Dincher , Gihan Mohammed , Serge Didier , Paul-Olivier Redon , Carine Cochet
Publication : Biogeochemistry
Date : 2019
Volume : 146
Issue : 1
Pages : 51-70
Catégorie(s)
#FORET Montiers #INRAERésumé
Abstract. The role of forest vegetation in the silicon (Si) cycle has been widely examined. However, to date, little is known about the specific role of fine roots. The main objective of our study was to assess the influence of fine roots on the Si cycle in a temperate forest in north-eastern France. Silicon pools and fluxes in vegetal solid and solution phases were quantified within each ecosystem compartment, i.e. in the atmosphere, above-ground and below-ground tree tissues, forest floor and different soil layers, on three plots, each with different soil types, i.e. Dystric Cambisol (DC), Eutric Cambisol (EC) and Rendzic Leptosol (RL). In this study, we took advantage of a natural soil gradient, from shallow calcic soil to deep moderately acidic soil, with similar climates, atmospheric depositions, species compositions and management. Soil solutions were measured monthly for 4 years to study the seasonal dynamics of Si fluxes. A budget of dissolved Si (DSi) was also determined for the forest floor and soil layers. Our study highlighted the major role of fine roots in the Si cycle in forest ecosystems for all soil types. Due to the abundance of fine roots mainly in the superficial soil layers, their high Si concentration (equivalent to that of leaves and 2 orders higher than that of coarse roots) and their rapid turnover rate (approximately 1 year), the mean annual Si fluxes in fine roots in the three plots were 68 and 110 for the RL and the DC, respectively. The turnover rates of fine roots and leaves were approximately 71 and 28% of the total Si taken up by trees each year, demonstrating the importance of biological recycling in the Si cycle in forests. Less than 1% of the Si taken up by trees each year accumulated in the perennial tissues. This study also demonstrated the influence of soil type on the concentration of Si in the annual tissues and therefore on the Si fluxes in forests. The concentrations of Si in leaves and fine roots were approximately 1.5–2.0 times higher in the Si-rich DC compared to the Si-poor RL. In terms of the DSi budget, DSi production was large in the three plots in the forest floor (9.9 to 12.7), as well as in the superficial soil layer (5.3 to 14.5), and decreased with soil depth. An immobilization of DSi was even observed at 90cm depth in plot DC (−1.7). The amount of Si leached from the soil profile was relatively low compared to the annual uptake by trees (13% in plot DC to 29% in plot RL). The monthly measurements demonstrated that the seasonal dynamics of the DSi budget were mainly linked to biological activity. Notably, the peak of dissolved Si production in the superficial soil layer occurred during winter and probably resulted from fine-root decomposition. Our study reveals that biological processes, particularly those involving fine roots, play a predominant role in the Si cycle in temperate forest ecosystems, while the geochemical processes appear to be limited.
Auteurs, date et publication :
Auteurs Marie-Pierre Turpault , Christophe Calvaruso , Gil Kirchen , Paul-Olivier Redon , Carine Cochet
Publication : Biogeosciences
Date : 2018
Volume : 15
Issue : 7
Pages : 2231-2249
Catégorie(s)
#FORET Montiers #INRAERésumé
The plant-available pools of calcium, magnesium and potassium are assumed to be stored in the soil as exchangeable cations adsorbed on the cation exchange complex. In numerous forest ecosystems, despite very low plant-available pools, elevated forest productivities are sustained. We hypothesize that trees access nutrient sources in the soil that are currently unaccounted by conventional soil analysis methods. We carried out an isotopic dilution assay to quantify the plant-available pools of calcium, magnesium and potassium and trace the soil phases that support these pools in 143 individual soil samples covering 3 climatic zones and 5 different soil types. For 81%, 87% and 90% of the soil samples (respectively for Ca, Mg and K), the plant-available pools measured by isotopic dilution were greater than the conventional exchangeable pool. This additional pool is most likely supported by secondary non-crystalline mineral phases in interaction with soil organic matter and represents in many cases (respectively 43%, 27% and 47% of the soil samples) a substantial amount of plant-available nutrient cations (50% greater than the conventional exchangeable pools) that is likely to play an essential role in the biogeochemical functioning of forest ecosystems, in particular when the resources of Ca, Mg and K are low.
Auteurs, date et publication :
Auteurs Jérémie Bel , Arnaud Legout , Laurent Saint-André , Steven J. Hall , Stefan Löfgren , Jean-Paul Laclau , Gregory van der Heijden
Publication : Scientific Reports
Date : 2020
Volume : 10
Issue : 1
Pages : 15703