Résumé
Ecological dynamics often exhibit significant temporal variability and sudden shifts that characterize their non-equilibrium and nonlinear nature, challenging our ability to understand and predict their trajectories. Among a set of ecological time series originating from the long-term monitoring of three large and deep lakes, nonlinear forecasting methods (Simplex projection and S-map) indicated that most of the time series exhibited hallmarks of complex dynamics in the form of nonlinear behaviors. Convergent Cross Mapping (CCM) was used to estimate the causal relationships among these time series by considering different time lags. The significant causal relationships were then used to construct causal networks from which nodes were characterized using PageRank and CheiRank. For the three lakes, the dominance of bottom-up control was revealed and was mostly indirect (i.e., nutrient-forcing zooplankton). This result likely evidences the transitivity of the causal relationships obtained by CCM as well as the mixed phytoplankton diet of zooplankton species limiting the identification of causal relationships among these two ecological components. Complementarily, the consistence of causal relationships for the different time lags may highlight a temporal transitivity by which the instantaneous causal signal was transmitted over time. The dual representation of both PageRank and CheiRank provided a straightforward classification of each node and enabled their thorough implications in the information flow within the causal networks. The complementary use of CCM and network metrics constituted an efficient way to delineate ecological causation using a high-resolution time series, for which linear methods performed poorly, and provided insights into the dynamic hierarchy of the different ecological variables in aquatic ecosystems.
Auteurs, date et publication :
Auteurs Victor Frossard , Frédéric Rimet , Marie-Elodie Perga
Publication : Ecological Modelling
Date : 2025
Volume : 368
Pages : 136-146
Catégorie(s)
#INRAE #OLAAuteurs, date et publication :
Auteurs Vincent Ducasse , Frédéric Darboux , Appoline Auclerc , Arnaud Legout , Jacques Ranger , Yvan Capowiez
Publication : Applied Soil Ecology
Date : 2021
Volume : 168
Pages : 104131
Catégorie(s)
#FORET Azerailles-Clermont #INRAERésumé
Crop residues restitution has significant impacts on soil biota, as it constitutes the main carbon (C) source in cultivated system, and differently alters belowground communities depending on its initial quality. However, functional consequences of such changes have mainly been studied considering few taxa, and less is known on the effects of biota differentiation in complex, un-manipulated communities. To evaluate the role of litters diverging qualities on soil fauna assemblages and functions during decomposition, we incorporated into the soil two litters of different qualities (high: pea or low: barley) in a long-term experimental research station studying the impacts of different cultural practices in Northern France. We measured initially and after 7 and 11 months the abundance and composition of main functional groups of soil fauna: bacterial-feeders, fungal-feeders, meso- and macro-detritivores. In parallel, we followed litter mass loss and quality, enzymatic activities (hydrolytic and oxidative), soil mineral N content, microbial and fungal biomass. Pea and barley litter qualities gradually diverged across time due to the faster depletion of cellulose in pea (−38%) than in barley (−18%), leading to contrasting enzymatic activities despite similar mass loss for both litters. Microbial-feeders exhibited more changes between the sampling dates rather than between the different litters. Contrastingly, detritivores (meso- and macro-) mirrored divergence in quality of pea and barley litters across time with increasing composition dissimilarities after 0, 7 and 11 months. As a consequence, enzymatic activities were better explained by detritivores rather than by microbial-feeders composition. These relationships suggested a direct link between the identity of the taxa stimulated and the nature of the top-down regulation during litter decomposition.
Auteurs, date et publication :
Auteurs Marie Sauvadet , Matthieu Chauvat , Nicolas Brunet , Isabelle Bertrand
Publication : Soil Biology and Biochemistry
Date : 2017
Volume : 107
Pages : 94-103
Catégorie(s)
#ACBB #ACBB Mons #INRAERésumé
Climate change is impacting temperate tree species phenology, especially the timing of budburst, which is mainly driven by air temperature. However, interactions with biotic or other environmental factors also influence the timing of budburst and are usually overlooked. We studied the influence of forest stand composition on the budburst date of adult trees belonging to two species: sessile oak (Quercus petraea, Matt. (Liebl.)) and Scots pine (Pinus sylvestris, L.). We monitored their budburst dates for seven consecutive years at 18 experimental plots located in central France. We compared the budburst dates of oaks and pines growing in monospecific stands with those of their counterparts in an oak-pine mixture. Our results show that sessile oak budburst date in mixed stands with Scots pine was delayed by 2.2 days on average (SE = 0.6) compared to its budburst date in monospecific stands. In years with early budburst, the delay was more pronounced - up to four days. For Scots pine, our results showed no difference between budburst dates in monospecific and mixed stands. We hypoth esize that the persistent foliage of the Scots pine in the mixed stand intercepted a part of the solar radiation, which affected the temperature perceived by the oak buds, thereby delaying the heat accumulation needed for sessile oak budburst. This effect may be of interest for the management of sessile oak in the context of global warming. In the future, sessile oak may experience more frequent frost damage due to an earlier budburst. Managing sessile oak with an evergreen species could limit late frost damage to some extent by delaying bud burst. Stand composition must obviously be taken into account when monitoring the phenology of temperate tree species and to enable robust comparisons of phenological events for a given tree species at different sites.
Auteurs, date et publication :
Auteurs Thomas Perot , Philippe Balandier , Camille Couteau , Nicolas Delpierre , Frédéric Jean , Sandrine Perret , Nathalie Korboulewsky
Publication : Agricultural and Forest Meteorology
Date : 2025
Volume : 300
Pages : 108326
Catégorie(s)
#FORET OPTMix #INRAERésumé
Repeated applications of organic amendments increase soil organic carbon (SOC) storage and nitrogen (N) availability for crops. Soil-crop models can facilitate the study of these effects and optimize the management of amendments. In soil-crop models, C and N mineralization of amendments is simulated by several pools of soil organic matter which have their specific turnover rate. We used the STICS model to quantify the effects of amendments on C and N dynamics in the long-term QualiAgro experiment, in which four amendments were spread every 2 years since 1998. We studied the model’s ability to simulate laboratory incubation and field experiments, depending on the calibration method and the partitioning of the amendment into one or two pools. The one-pool model simulated C and N dynamics in the field experiment as accurately as the two-pools model with a calibration based on field data. However, C and N dynamics measured under laboratory conditions could only be simulated with the two-pools model, which was then used to simulate C and N in the field. The root mean square errors were 1.6 t DM ha−1 for grain yield, 2.6 t C ha−1 for SOC and 41 kg N ha−1 for soil mineral N. Model parameters could be determined using the C:N ratio of amendments and the indicator of remaining organic carbon (IROC), measured at the laboratory. The STICS model can thus be used to simulate SOC and N dynamics with long-term amendments with a simple calibration.
Auteurs, date et publication :
Auteurs Florent Levavasseur , Bruno Mary , Sabine Houot
Publication : Nutrient Cycling in Agroecosystems
Date : 2021
Volume : 119
Issue : 1
Pages : 103-121
Catégorie(s)
#ANR-Citation #INRAE #PRO #PRO QualiAgroAuteurs, date et publication :
Auteurs T. Sterckeman , L. Gossiaux , S. Guimont , C. Sirguey , Z. Lin
Publication : Science of the Total Environment
Date : 2025
Volume : 639
Pages : 1440-1452
Catégorie(s)
#ANR-Citation #INRAE #PRO #PRO ColmarRésumé
The leaf area index (LAI) is a key characteristic of forest ecosystems. Estimations of LAI from satellite images generally rely on spectral vegetation indices (SVIs) or radiative transfer model (RTM) inversions. We have developed a new and precise method suitable for practical application, consisting of building a species-specific SVI that is best-suited to both sensor and vegetation characteristics. Such an SVI requires calibration on a large number of representative vegetation conditions. We developed a two-step approach: (1) estimation of LAI on a subset of satellite data through RTM inversion; and (2) the calibration of a vegetation index on these estimated LAI. We applied this methodology to Eucalyptus plantations which have highly variable LAI in time and space. Previous results showed that an RTM inversion of Moderate Resolution Imaging Spectroradiometer (MODIS) near-infrared and red reflectance allowed good retrieval performance (R-2 = 0.80, RMSE = 0.41), but was computationally difficult. Here, the RTM results were used to calibrate a dedicated vegetation index (called "EucVI") which gave similar LAI retrieval results but in a simpler way. The R-2 of the regression between measured and EucVI-simulated LAI values on a validation dataset was 0.68, and the RMSE was 0.49. The additional use of stand age and day of year in the SVI equation slightly increased the performance of the index (R-2 = 0.77 and RMSE = 0.41). This simple index opens the way to an easily applicable retrieval of Eucalyptus LAI from MODIS data, which could be used in an operational way.
Auteurs, date et publication :
Auteurs Guerric Le Maire , Claire Marsden , Yann Nouvellon , Jose-Luiz Stape , Flavio Jorge Ponzoni
Publication : Remote Sensing
Date : 2012
Volume : 4
Issue : 12
Pages : 3766-3780
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs Yann Dumas , Pierre Boudier
Publication : Symbioses
Date : 2025
Issue : 35-36
Pages : 35-46
Catégorie(s)
#FORET OPTMix #INRAERésumé
In the last 10 years, many atypical novel members of Brucella species have been reported, including several Brucella inopinata-like strains in wild-caught and “exotic” amphibians from various continents. In 2017, a strain of Brucella was isolated for the first time in animals from a French farm producing frogs—Pelophylax ridibundus—for human consumption and identified as B. microti-like. Following this first isolation, investigations were performed in this farm as well as in the farm of the research unit that provided the domestic frog strain to estimate the prevalence of B. microti-like infection and its presence in the surrounding environment. Farming practices were investigated and samples including frogs at different development stages, surface tank swabs, water, feed and soil were analysed by real-time PCR and bacteriological methods. High B. microti-like prevalence values (higher than 90%) were obtained in frog samples in the commercial farm, and its presence was highlighted in the environmental samples except feed. In the research unit farm, B. microti-like species was also isolated and detected in frog and environmental samples. These results show that B. microti-like organisms are able to colonize amphibians and persist in their environment. Its presence could constitute a possible risk for consumers and workers proving the importance of assessing the zoonotic and pathogenic potentials of these new and atypical Brucella species.
Auteurs, date et publication :
Auteurs Maryne Jaÿ , Luca Freddi , Virginie Mick , Benoit Durand , Guillaume Girault , Ludivine Perrot , Benoit Taunay , Thomas Vuilmet , Didier Azam , Claire Ponsart , Gina Zanella
Publication : Transboundary and Emerging Diseases
Date : 2025
Volume : 67
Issue : 2
Pages : 617-625
Catégorie(s)
#INRAE #PEARLAuteurs, date et publication :
Auteurs Lyria Berdjeb , Jean-François Ghiglione , Stéphan Jacquet
Publication : Applied and Environmental Microbiology
Date : 2011
Volume : 77
Issue : 11
Pages : 3591-3599