Résumé
Potassium (K) is an important limiting factor of tree growth, but little is known of the effects of K supply on the long-distance transport of photosynthetic carbon (C) in the phloem and of the interaction between K fertilization and drought. We pulse-labelled 2-year-old Eucalyptus grandis L. trees grown in a field trial combining K fertilization (+K and −K) and throughfall exclusion (+W and −W), and we estimated the velocity of C transfer by comparing time lags between the uptake of 13CO2 and its recovery in trunk CO2 efflux recorded at different heights. We also analysed the dynamics of the labelled photosynthates recovered in the foliage and in the phloem sap (inner bark extract). The mean residence time of labelled C in the foliage was short (21–31 h). The time series of 13C in excess in the foliage was affected by the level of fertilization, whereas the effect of throughfall exclusion was not significant. The velocity of C transfer in the trunk (0.20–0.82 m h−1) was twice as high in +K trees than in −K trees, with no significant effect of throughfall exclusion except for one +K −W tree labelled in the middle of the drought season that was exposed to a more pronounced water stress (midday leaf water potential of −2.2 MPa). Our results suggest that besides reductions in photosynthetic C supply and in C demand by sink organs, the lower velocity under K deficiency is due to a lower cross-sectional area of the sieve tubes, whereas an increase in phloem sap viscosity is more likely limiting phloem transport under drought. In all treatments, 10 times less 13C was recovered in inner bark extracts at the bottom of the trunk when compared with the base of the crown, suggesting that a large part of the labelled assimilates has been exported out of the phloem and replaced by unlabelled C. This supports the ‘leakage-retrieval mechanism’ that may play a role in maintaining the pressure gradient between source and sink organs required to sustain high velocity of phloem transport in tall trees.
Auteurs, date et publication :
Auteurs D. Epron , O.-M. Rodrigues Cabral , J.-P. Laclau , M. Dannoura , A.-P. Packer , C. Plain , P. Battie Laclau , Z. Moreira Marcelo , P.-C.-O. Trivelin , J.-P. Bouillet , D. Gérant , Y. Nouvellon
Publication : Tree Physiology
Date : 2025
Volume : 36
Issue : 1
Pages : 6-21
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
Management and remediation actions of polycyclic aromatic hydrocarbons (PAH) contaminated sites require an accurate knowledge of the dynamics of these chemicals in situ under real conditions. Here we developed, under the Virtual Soil Platform, a global model for PAH that describes the principal physical and biological processes controlling the dynamics of PAH in soil under real climatic conditions. The model was applied first to simulate the observed dynamics of phenanthrene in situ field experimental plots of industrial contaminated soil. In a second step, different long-term scenarios of climate change or bioavailability increase were applied. Our results show that the model can adequately predict the fate of phenanthrene and can contribute to clarify some of unexplored aspects regarding the behavior of phenanthrene in soil like its degradation mechanism and stabilization. Tested prospective scenarios showed that bioavailability increase (through the addition of solvent or surfactants) resulted in significant increase in substrate transfer rate, hence reducing remediation time. Regarding climate change effect, the model indicated that phenanthrene concentration decreased by 54% during 40years with a natural attenuation and both scenarios chosen for climatic boundaries provided very similar results.
Auteurs, date et publication :
Auteurs Khaled Brimo , Patricia Garnier , François Lafolie , Geoffroy Séré , Stéphanie Ouvrard
Publication : Science of The Total Environment
Date : 2018
Volume : 619-620
Pages : 239-248
Catégorie(s)
#INRAE #VirtualSoilAuteurs, date et publication :
Auteurs Viet Tran-Khac , Philippe Quetin , Isabelle Domaizon , Stéphan Jacquet , Laurent Espinat , Clémentine Gallot , Serena Rasconi
Publication : Data in Brief
Date : 2025
Volume : 32
Pages : 106255
Catégorie(s)
#INRAE #OLARésumé
Used for several decades and recognized today as a reliable method, fishery acoustics is commonly used in scientific studies and monitoring surveys. In Europe, during the last decades, the most frequently used scientific echo-sounder has been the EK60 from the Simrad company (Simrad Kongsberg Maritime AS, Horten, Norway). A new echo-sounder model, the EK80, has been recently developed, and it is therefore necessary to check whether the results obtained by the two generations of echo-sounder (EK60 and EK80) give the same results. This is of main importance in the context of time series. Recent works have already addressed this comparison, focusing on SA (nautical area backscattering coefficient) but the systems’ reliability to accurately measuring target strength (TS, in dB) has only been tested using calibration spheres. Our work aims to test the hypothesis that, at a given frequency, the TS recorded simultaneously in situ by an EK60 and an EK80, in CW mode, were not statistically different. Data were recorded in two peri-alpine lakes using the two systems sampling sequentially a similar volume. Using statistical tests, acoustics metrics were compared. For TS, statistically significant differences were found between the two generations of echo-sounder. However, these differences were not large enough to affect the fish density used for fishery management or researches on the fish population. The continuity of the time series acquired with the EK60 is ensured when one switches to the EK80 echo-sounder for lake ecosystem research and monitoring.
Auteurs, date et publication :
Auteurs Clément Rautureau , Chloé Goulon , Jean Guillard
Publication : Fisheries Research
Date : 2025
Volume : 249
Pages : 106237
Catégorie(s)
#INRAE #OLARésumé
Several studies have emphasised the ability of Near Infrared Reflectance Spectroscopy (NIRS) to identify surface earthworm casts in the field. However, less is known about casts deposited within the soil, which usually represent the majority found in the field. This study tested the ability of NIRS to identify belowground casts in agricultural systems. Casts and surrounding soils were sampled at depths of 20-30 cm in a loamy soil under no tillage for 12 years. To distinguish different types of cast, sizes and orientations relative to the horizontal plane were measured. NIRS analyses and analyses of carbon and nitrogen content were also performed to compare casts to surrounding soils. Casts were classified into 4 size classes, with no preferential orientation. Cast carbon and nitrogen content were not influenced by their size and did not differ from surrounding soils. PCAs performed on the NIRS data did not allow casts to be differentiated from surrounding soils, regardless of size class. However, soil aggregates were clearly differentiated probably due to their spatial distribution in the soil. Although this study did not identify specific NIRS signatures for casts, it shows the utility of this method to investigate the origin of the soil consumed by earthworms. In our case, NIRS analyses suggest that the high bulk density of the soil (1.42 g cm(-3)) forced ingestion by endogeic earthworms, simply to move around, without preferential selection for organic matter. Consequently, their casts were deposited a few mm from where they had ingested soil with similar organic matter quality. (c) 2013 Elsevier B.V. All rights reserved.
Auteurs, date et publication :
Auteurs N. Bottinelli , Y. Capowiez , V. Hallaire , J. Ranger , P. Jouquet
Publication : Applied Soil Ecology
Date : 2013
Volume : 70
Pages : 57-61
Catégorie(s)
#FORET Azerailles-Clermont #INRAEAuteurs, date et publication :
Auteurs M. Annabi , Y. Le Bissonnais , M. Le Villio-Poitrenaud , S. Houot
Publication : Agriculture, Ecosystems and Environment
Date : 2025
Volume : 144
Issue : 1
Pages : 382-389
Catégorie(s)
#INRAE #PRO #PRO QualiAgroRésumé
The evaluation of the taxa–area relationship (TAR) with molecular fingerprinting data demonstrated the spatial structuration of soil microorganisms and provided insights into the processes shaping their diversity. The increasing use of massive sequencing technologies in biodiversity investigations has now raised the question of the advantages of such technologies over the fingerprinting approach for elucidation of the determinism of soil microbial community assembly in broad-scale biogeographic studies. Our objectives in this study were to compare DNA fingerprinting and meta-barcoding approaches for evaluating soil bacterial TAR and the determinism of soil bacterial community assembly on a broad scale. This comparison was performed on 392 soil samples from four French geographic regions with different levels of environmental heterogeneity. Both molecular approaches demonstrated a TAR with a significant slope but, because of its more sensitive description of soil bacterial community richness, meta-barcoding provided significantly higher and more accurate estimates of turnover rates. Both approaches were useful in evidencing the processes shaping bacterial diversity variations on a broad scale. When different taxonomic resolutions were considered for meta-barcoding data, they significantly influenced the estimation of turnover rates but not the relative importance of each component process. Altogether, DNA meta-barcoding provides a more accurate evaluation of the TAR and may lead to re-examination of the processes shaping soil bacterial community assembly. This should provide new insights into soil microbial ecology in the context of sustainable use of soil resources.
Auteurs, date et publication :
Auteurs S. Terrat , S. Dequiedt , W. Horrigue , M. Lelievre , C. Cruaud , N. P. A. Saby , C. Jolivet , D. Arrouays , P.-A. Maron , L. Ranjard , N. Chemidlin Prévost-Bouré
Publication : Heredity
Date : 2025
Volume : 114
Issue : 5
Pages : 468-475
Catégorie(s)
#ANR-Citation #Genosol #INRAERésumé
Net Surface Heat Flux (SurHF) was estimated from 2008 to 2014 for Lake Geneva (Switzerland/France), using long-term temperature depth profiles at two locations, hourly maps of reanalysis meteorological data from a numerical weather model and lake surface water temperatures from calibrated satellite imagery. Existing formulas for different heat flux components were combined into 54 different total SurHF models. The coefficients in these models were calibrated based on SurHF optimization. Four calibration factors characterizing the incoming long-wave radiation, sensible, and latent heat fluxes were further investigated for the six best performing models. The combination of the modified parameterization of the Brutsaert equation for incoming atmospheric radiation and of similarity theory-based bulk parameterization algorithms for latent and sensible surface heat fluxes provided the most accurate SurHF estimates. When optimized for one lake temperature profile location, SurHF models failed to predict the temperature profile at the other location due to the spatial variability of meteorological parameters between the two locations. Consequently, the optimal SurHF models were calibrated using two profile locations. The results emphasize that even relatively small changes in calibration factors, particularly in the atmospheric emissivity, significantly modify the estimated long-term heat content. The lack of calibration can produce changes in the calculated heat content that are much higher than the observed annual climate change-induced trend. The calibration improved parameterization of bulk transfer coefficients, mainly under low wind regimes.
Auteurs, date et publication :
Auteurs Abolfazl Irani Rahaghi , Ulrich Lemmin , Andrea Cimatoribus , Damien Bouffard , Michael Riffler , Stefan Wunderle , David Andrew Barry
Publication : Limnology and Oceanography: Methods
Date : 2025
Volume : 16
Issue : 9
Pages : 576-593
Catégorie(s)
#INRAE #OLARésumé
Key message Near- and mid-infrared spectroscopy allows for the detection of local patterns of forest soil properties. In combination with dendrometric data, it may be used as a prospective tool for determining soil heterogeneity before setting up long-term forest monitoring experiments. Context Forest soils and stands generally exhibit higher spatial heterogeneity than other terrestrial ecosystems. This variability needs be taken into account before setting up long-term forest monitoring experiments to avoid multiple interactions between local heterogeneity and the factors tested in the experiment. Aims We hypothesized that raw near- and mid-infrared spectra can be used as an integrated proxy of a large set of soil properties. The use of this method, in combination with dendrometric data, should provide a quick and cost-effective tool for optimizing the design of experimental forest sites. Methods We assessed the local soil heterogeneity at 11 experimental sites in oak and beech stands, which belong to a new forest long-term ecological research (LTER) network. We used near- and mid-infrared spectroscopy in soil and litter samples. The spectra were subjected to principal components analyses (PCA) to determine the intra-site variability of the soil and litter layers. Results Based on mapped PCA coordinates and basic dendrometric data, it was possible to design the experiment and minimize the interactions between the treatment layout and the tested variables. The method was validated with chemical analyses of the soil. No interaction was detected at the set-up of the experiment between the treatment layout and chemical soil properties (C, N, C/N ratio, pH, CEC, Al, Mg, P2O5, Fe, Mn, Na, and K). Conclusion Near-infrared (NIR) and mid-infrared (MIR) spectroscopy is a useful tool for characterizing the overall heterogeneity of soil chemical properties. It can be used without any preliminary calibration. In combination with dendrometric data, it provides a reliable method for optimizing LTER plots in different types of ecosystems.
Auteurs, date et publication :
Auteurs Emila Akroume , Bernd Zeller , Marc Buée , Philippe Santenoise , Laurent Saint-André
Publication : Annals of Forest Science
Date : 2016
Volume : 73
Issue : 4
Pages : 1005-1013
Catégorie(s)
#ANR-Citation #INRAE #M-POETERésumé
During the last 10 years, several attempts to map soil attributes at the scale of mainland France have been realised. We exemplify them by seven major outputs: maps of organic C stocks, trace elements (TE), microbial density and diversity, soil thickness, available water capacity (AWC), extractable P, and changes in soil pH. We first briefly describe the data and the methods used to produce these maps and summarise their main results. We then focus on their impacts on various categories of the public, i.e. the general public and citizens; farmers; private companies; non-governmental organisations; agricultural development organisations, stakeholders, and national agencies; French governmental bodies; and international organisations. We also analyse the demands that came to the French National Soil Information Centre from 2008 to 2018 and the impact that our activities had in various media. Soil organic C had the largest impact in nearly all categories of end-users, which may be linked to the recent `4 per 1000' initiative launched by the French governmentduring the COP21 and to the fact that farmers are interested in increasing the organic matter content of their soil for increasing the fertility. TE obtained high scores, which may be related to citizens' care about health and to the fact that governmental bodies and national agencies have a major interest in site contamination assessments. The soil P content, pH, and AWC exhibited major impacts on the agricultural sector. Maps of the soil P content and pH were used as geomarketing tools by private companies selling fertilisers and soil amendments, whereas the AWC was already incorporated into decision-making aid tools for irrigation management developed by development organisations for farmers. Microbial diversity generated collaborations with a large network of farmers and had a large media impact. Nevertheless, the visibility of soil information to the general public should be increased. This can be done by using new multimedia and interactive tools. Overall, these selected examples of digital soil mapping of soil attributes at the national scale in France clearly indicate that the soil attributes have substantial impact on various categories of end-users, such as farmers, professional organisations, stakeholders, and policymakers at different levels of decision-making, among others. However, the impacts on the general public and citizens are more difficult to quantify, and increasing the soil awareness of the general public should be of high priority. (C) 2020 Elsevier B.V. All rights reserved.
Auteurs, date et publication :
Auteurs Dominique Arrouays , Anne C. Richer-de-Forges , Florence Helies , Vera Leatitia Mulder , Nicolas P. A. Saby , Songchao Chen , Manuel P. Martin , Mercedes Roman Dobarco , Stephane Follain , Claudy Jolivet , Bertrand Laroche , Thomas Loiseau , Isabelle Cousin , Marine Lacoste , Lionel Ranjard , Benoit Toutain , Christine Le Bas , Thomas Eglin , Marion Bardy , Veronique Antoni
Publication : GEODERMA REGIONAL
Date : 2020
Volume : 23