Auteurs, date et publication :
Auteurs Naoise Nunan , Julie Leloup , Léo S. Ruamps , Valérie Pouteau , Claire Chenu
Publication : Scientific Reports
Date : 2025
Volume : 8
Issue : 1
Catégorie(s)
#Genosol #INRAERésumé
Lake biological parameters show important spatio-temporal heterogeneities. This is why explaining the spatial patchiness of phytoplankton abundance has been a recurrent ecological issue and is an essential prerequisite for objectively assessing, protecting and restoring freshwater ecosystems. The drivers of these heterogeneities can be identified by modeling their dynamics. This approach is useful for theoretical and applied limnology. In this study, a 3D hydrodynamic model of Lake Geneva (France/Switzerland) was created. It is based on the Delft3D suite software and includes the main tributary (Rhône River) and two-dimensional high-resolution meteorological forcing. It provides 3D maps of water temperature and current velocities with a 1 h time step on a 1 km horizontal grid size and with a vertical resolution of 1 m near the surface to 7 m at the bottom of the lake. The dynamics and the drivers of phytoplankton heterogeneities were assessed by combining the outputs of the model and chlorophyll-a concentration (Chl-a) data from MERIS satellite images between 2008 and 2012. Results highlight physical mechanisms responsible for the occurrence of seasonal hot-spots in phytoplankton abundance in the lake. At the beginning of spring, Chl-a heterogeneities are usually caused by an earlier onset of phytoplankton growth in the shallowest and more sheltered areas; spatial differences in the timing of phytoplankton growth can be explained by spatial variability in thermal stratification dynamics. In summer, transient and locally higher phytoplankton abundances are observed in relation to the impact of basin-scale upwelling.
Auteurs, date et publication :
Auteurs Frédéric Soulignac , Pierre-Alain Danis , Damien Bouffard , Vincent Chanudet , Etienne Dambrine , Yann Guénand , Tristan Harmel , Bastiaan W. Ibelings , Dominique Trevisan , Rob Uittenbogaard , Orlane Anneville
Publication : Journal of Great Lakes Research
Date : 2025
Volume : 44
Issue : 4
Pages : 756-764
Catégorie(s)
#INRAE #OLARésumé
The priming effect in soil is proposed to be generated by two distinct mechanisms: ‘stoichiometric decomposition’ and/or ‘nutrient mining’ theories. Each mechanism has its own dynamics, involves its own microbial actors, and targets different soil organic matter (SOM) pools. The present study aims to evaluate how climatic parameters drive the intensity of each priming effect generation mechanism via the modification of soil microbial and physicochemical properties. Soils were sampled in the center of Madagascar, along climatic gradients designed to distinguish temperature from rainfall effects. Abiotic and biotic soil descriptors were characterized including bacterial and fungal phylogenetic composition. Potential organic matter mineralization and PE were assessed 7 and 42 days after the beginning of incubation with 13C-enriched wheat straw. Both priming mechanisms were mainly driven by the mean annual temperature but in opposite directions. The priming effect generated by stoichiometric decomposition was fostered under colder climates, because of soil enrichment in less developed organic matter, as well as in fast-growing populations. Conversely, the priming effect generated by nutrient mining was enhanced under warmer climates, probably because of the lack of competition between slow-growing populations mining SOM and fast-growing populations for the energy-rich residue entering the soil. Our study leads to hypotheses about the consequences of climate change on both PE generation mechanisms and associated consequences on soil carbon sequestration.
Auteurs, date et publication :
Auteurs Kanto Razanamalala , Tantely Razafimbelo , Pierre-Alain Maron , Lionel Ranjard , Nicolas Chemidlin , Mélanie Lelièvre , Samuel Dequiedt , Volaniaina H. Ramaroson , Claire Marsden , Thierry Becquer , Jean Trap , Eric Blanchart , Laetitia Bernard
Publication : The ISME Journal
Date : 2018
Volume : 12
Issue : 2
Pages : 451-462
Catégorie(s)
#Genosol #INRAERésumé
Key messageIn order to record the seasonal changes in aboveground biomass production (trunk and branches) in a forest, changes in wood density must be taken into account. A 60-year-old beech forest displayed a large intra-annual variability in its aboveground woody biomass production efficiency. This variation followed a seasonal trend with a maximum during the summer while gross primary production was rather low.ContextIn the current context of land use and climate change, there is a need to precisely quantify the carbon (C) balance of forest ecosystems, and more specifically, of C allocation to tree compartments.AimsWe quantified the seasonal changes in the aboveground biomass production (aBP) of a beech forest growing on two different soils: an alocrisol and a calci-brunisol. In addition, for the alocrisol ecosystem, we assessed the existence and degree of intra-annual variability in the ratio of wood aBP to gross primary production (GPP), i.e., the wood aBP efficiency.MethodsThe study site is a 60-year-old beech forest in northeastern France. An eddy covariance tower records continuously net ecosystem exchange. To investigate the temporal changes in aBP, mini-cores were drilled and diameter at breast height measurements were taken on a monthly basis from 45 trees for both stands studied over 2014.ResultsA clear difference in aBP was observed between the two soils with the alocrisol being more productive than the calci-brunisol. For the alocrisol, both woody aBP and GPP changed over the course of the year, reaching peak values during June (6 and 12.5 gC m−2 day−1, respectively). Wood applied bias photon-to-current efficiency aboveground Biomass Production Efficiency (aBPE) also showed important intra-annual variations, ranging from 0.09 in September to 0.58 in July. Wood density varied throughout the year, and not taking it into account would have led to an overestimation of aBP by as much as 20% in April and May.ConclusionOur study highlights the importance of taking wood density into account for intra-annual studies of aBP. Wood aBPE cannot be considered as constant as it fluctuated from 0.09 to 0.58 throughout the year for an annual value of 0.34. The potential error in wood aBPE stemming from not taking these changes into account amounts to 15%.
Auteurs, date et publication :
Auteurs Laura Heid , Christophe Calvaruso , Anjy Andrianantenaina , André Granier , Sébastien Conil , Cyrille B. K. Rathgeber , Marie-Pierre Turpault , Bernard Longdoz
Publication : Annals of Forest Science
Date : 2018
Volume : 75
Issue : 1
Pages : 31
Catégorie(s)
#FORET Montiers #INRAERésumé
Aleppo pine (Pinus halepensis Mill.) is one of the dominant conifer species in the Mediterranean area. Many studies have investigated the role of climate variables (precipitations, temperature) in its occurrence and growth, but few have taken the effect of local site conditions into account, nor their interaction with climate. This study aimed at thoroughly assessing forest sites potential for Aleppo pine in France, and designing a practical tool to help forest managers implementing these results. The study is based on a network of 512 plots laid out in the French Mediterranean area, where 2158 trees were measured. A site index was computed using a height growth model calibrated on these plots. Using neural networks and partial least square regression models (PLS), we disentangled the effects of climatic factors and local site conditions in Aleppo pine presence and growth. Local water balance (assessed through topography, soil, geology and legacies of past human activities) was the main factor driving Aleppo pine productivity in the study area. Climate played a significant role as a whole but more important at the species distribution margins, frost and snow limiting Aleppo pine range northwards and in elevation. Based on these results, a practical tool was designed for two different types of mother rocks to help assessing forest site potential for Aleppo pine. As the span of climate conditions in south-eastern France includes most of those found in Aleppo pine distribution area, except the driest and hottest ones found in its southernmost locations, this study could easily be used or adapted in most other concerned countries. Because of the ongoing climate change and increasing drought in the Mediterranean area, the balance between local and climate factors may change in time and space. Our results show that without an accurate knowledge of local conditions, the impact of climate change cannot be predicted.
Auteurs, date et publication :
Auteurs Michel Vennetier , Christian Ripert , Cyrille Rathgeber
Publication : Forest Ecology and Management
Date : 2018
Volume : 413
Pages : 32-47
Catégorie(s)
#FORET FontBlanche #INRAERésumé
Large worldwide sources of dust, such as the Saharan desert, play a key role in the amounts and composition of atmospheric particulate deposition (APD), but their relative contribution compared to other sources remain unclear. Our study aimed to apportion Saharan, regional, and anthropogenic sources of APD in three sampling along a long transect affected by Saharan outbreaks. We quantified total APD, and analyzed its mineralogical and chemical composition between 2011 and 2012. . Strong markers of Saharan dust, such as large amounts of APD and of a low Al2O3:CaO ratio allowed identifying clear periods influenced by Saharan outbreaks. Nitrogen and phosphorus reflected soil affected by agricultural practices, while Cd, Pb, Sb and Sn tracked traffic and industrial sources – as confirmed by enrichment factors. Then, we designed a conceptual model including sensitivity analyses to estimate the contribution of unanalyzed (10–11%, likely chlorites or sulfates), organic (34–41%), anthropogenic (11–22%), mineral-regional (5–25%) and mineral-Saharan (10–38%) matter over our entire study period. Our study shows the rapidly decreasing contribution of Saharan outbreaks – and the decreasing flux of Ca and Mg, from 40 to 0.4 kg.ha−1 over the study period between Algeria and France. Yet, Saharan outbreaks were still noticeable in APD at a site 1500 km away. Our study also shows the large relative contribution of organic and anthropogenic sources to APD in the three sampling sites, and their possible influence on nutrient budgets.
Auteurs, date et publication :
Auteurs Emeline Lequy , Anna Avila , Malika Boudiaf Nait Kaci , Marie-Pierre Turpault
Publication : Atmospheric Environment
Date : 2018
Volume : 191
Pages : 181-193
Catégorie(s)
#FORET Montiers #INRAERésumé
Coppice forestry is a conventional silvicultural practice that takes advantage of a tree’s capacity to respond to disturbances by sprouting. Sprouting capacity is determined by many intrinsic and extrinsic factors such as parent tree age/size, understory light availability and deer browsing, which, under closed canopy conditions are important limiting factors for stump survival or sprout growth. However, the combined effect of potentially confounding abiotic and biotic factors on stump survival and sprout growth remains elusive, even more so under closed canopy conditions. This study aims to quantify the effect of deer browsing on stump mortality and sprout growth under closed-canopy conditions and to compare this effect with other known determinants. Here we show that stump survival and sprout growth in sessile oak (Quercus petraea Matt.) depend on deer browsing, understory light availability and the diameter of the parent tree. By studying paired fenced-unfenced plots, we confirmed that deer browsing decreased stump survival and inhibited sprout growth. Furthermore, by taking advantage of a gradient in understory light availability in monospecific and mixed stands of sessile oak and Scots pine (Pinus sylvestris L.), we showed a clear positive linear relationship between sprout growth and light availability. This relationship explained the observed differences among stand composition types. Finally, we found that increased understory light availability did not compensate for losses due to deer browsing. In the absence of deer browsing, our results demonstrate that sessile oak stumps regenerate well under closed-canopy conditions and maintain a moderate sprouting capacity at least until the age of 70–80 years old. Partial thinning could therefore be a potential tool to renew light-demanding tree species such as sessile oak in mixed high-forest stands. Nevertheless, we do not recommend coppicing sessile oak under closed canopies unless the oak stumps are protected from deer browsing and understory light availability is optimized as much as possible despite closed-canopy-management objectives.
Auteurs, date et publication :
Auteurs Anders Mårell , Jean-Pierre Hamard , Thomas Pérot , Sandrine Perret , Nathalie Korboulewsky
Publication : Forest Ecology and Management
Date : 2018
Volume : 430
Pages : 134-142
Catégorie(s)
#FORET OPTMix #INRAERésumé
Key messageAggregation was studied in two acidic forest soils (NE France) to investigate the potential link between available Ca and Mg content and soil aggregate size distribution and properties. Clay content influenced the aggregation status while clay mineralogy influenced aggregate stability and dynamics. Aggregation status and reactivity of soil components contributed to the difference of exchangeable Ca and Mg content in topsoil between the two sites.ContextThough nutrient fluxes are important to define forest soil chemical fertility, the quantification of nutrient reservoirs in the soils and their availability to tree uptake is essential. A thorough understanding of nutrient availability requires an investigation of nutrient location and distribution in the soil solid phase.AimsThe general aim was to investigate the potential link between available Ca and Mg content and soil aggregate size distribution and their properties (chemical, physical, mineralogical).MethodsSoil aggregates were separated according to three size classes (200-2000m; 50-200m; <50m) in two forest soils of the Lorraine plateau (France), both classified as Luvisols ruptic. The physical, chemical, and mineralogical properties were measured for each aggregate class.ResultsWe showed that the relative abundance of an intermediate aggregate class [200-50m] was relevant to explain the difference of exchangeable Ca and Mg between sites. These aggregates were the poorest in organic and reactive mineral components and were unstable, which may mitigate the retention of Ca and Mg by ion-exchange.ConclusionThis study highlights the role of aggregation and reactivity of soil components as relevant determinants of cation availability to tree uptake in soils.
Auteurs, date et publication :
Auteurs Lea Bedel , Arnaud Legout , Anne Poszwa , Gregory van der Heijden , Melanie Court , Noemie Goutal-Pousse , Emmanuelle Montarges-Pelletier , Jacques Ranger
Publication : Annals of Forest Science
Date : 2018
Volume : 75
Issue : 4
Catégorie(s)
#FORET Azerailles-Clermont #INRAERésumé
Numerous studies predict a short-term important decrease in fossil resources and stress the need to develop alternative renewable energies, thus European countries aim at increasing biomass production for energetic purposes. One such source of bioenergy could be obtained from forest biomass pools by exporting logging residues, yet this practice would have strong impacts on forest ecosystems (e.g. disturbance of soil biodiversity and chemical properties). Most studies on biomass removal effects focused on boreal forests but responses in temperate forests are still scarcely studied. Soil macrofauna is involved in forest ecosystem functioning through numerous chemical, physical and biological processes and multiple interactions with other organisms. A disturbance of the soil macrofauna community can thus lead to a response of the forest ecosystem as a whole. Experimental plots were set up in 6 northern France forests (either dominated by oak or beech), with a treatment corresponding to Whole Tree Harvesting (WTH) practices compared to control, in order to characterize the response of soil macrofaunal communities to organic matter (OM) export. Our study showed that OM export leads to a short-term loss of abundance in macrofaunal communities in temperate deciduous forest soils that can also lead to an alteration of soil OM cycle, and revealed that the breadth of this negative impact is modulated by tree species and faunal trophic groups. Furthermore, some results of community responses were directly applicable to forest management as marked responses of several taxa revealed four bioindicators of OM disturbance. Therefore, the level of disturbance related to new forest management practices, such as WTH to increase forest biofuel yields, (i) could be characterized by surveying either total soil macrofauna or using tools such as bioindicator taxa and (ii) should be assessed regarding tree stand identity.
Auteurs, date et publication :
Auteurs François Elie , Lucie Vincenot , Thierry Berthe , Edouard Quibel , Bernhard Zeller , Laurent Saint-André , Matthieu Normand , Matthieu Chauvat , Michaël Aubert
Publication : Forest Ecology and Management
Date : 2018
Volume : 429
Pages : 549-557
Catégorie(s)
#INRAE #M-POETEAuteurs, date et publication :
Auteurs Leandro Dalla Valle , Karen Regina Castelli , Mariana Gregório Barreto , Jean-Paul Laclau , Marcos Sandro Felipe , Alexandre Marco Da Silva
Publication : Communications in Soil Science and Plant Analysis
Date : 2025
Volume : 50
Issue : 2
Pages : 209-227