Résumé
Mangrove ecosystems are one of the most carbon dense ecosystems worldwide. Yet, the stabilization and recalcitrance of carbon (C) and organic matter (OM) are little understood in mangroves, especially across eco-geomorphological settings and depths. Here, we characterized the sediment C and OM of Indo-Pacific mangroves, located in four distinct eco-geomorphological settings (i.e., delta, estuary, non-carbonated open coast, carbonated open coast) and at two different depths (i.e., 0-20 cm and 80-100 cm). We quantified the fraction of C within (i) mineralized associated organic matter (MAOM), and (ii) within particulate organic matter (POM). We coupled these analyses with lignin quantity and composition, as well as stable C isotopes analysis in mangrove sediments.We found significant variation in the quantity of MAOM and POM across mangrove eco-geomorphological settings, but not across mangrove sediment depths. The terrigenous deltaic mangrove exhibited up to three times more MAOM than the carbonate open coast mangrove, which was dominated by POM. Mangroves of the carbonate coast type had higher C content than other eco-geomorphic types. The was not different across mangrove eco-geomorphologies, but was different across mangrove sediment depths. Regarding OM recalcitrance, the lignin content displayed strong variations across the different eco-geomorphologies, however, there was no clear pattern of lignin degradation stage across depths. Finally, an inverse correlation between sediment C recalcitrance (i.e., lignin content) and stabilization (MAOM) processes were determined across mangroves.Our findings suggest that the processes leading to OM preservation differ among mangroves in various eco-geomorphological settings. Those results have important implications to guide mangrove restoration for carbon persistence and to model carbon pools across mangrove areas.
Auteurs, date et publication :
Auteurs Marion Maceiras , Marie Arnaud , Catherine Lovelock , Alex Pearse , Huyen Dang , Sarah Robin , Cyril Marchand , Axel Felbacq , Samuel Abiven , Johanne Lebrun Thauront , Nicolas Bottinelli , Amrit kumar Mishra , Syed Hilal Farooq , Tuhin Bhadra , Cornelia Rumpel
Date : 2024
Pages : 8023
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
This study focuses on the evolution of soil erosion rates on artificial covers for low level radioactive waste in the context of climate change. The objective is to test the impacts on erosion of (i) increasing rainfall intensities during storms and (ii) decreasing soil moisture content before storms. The “Centre de stockage de la Manche” (CSM) in Normandy, France, where Low-Level Nuclear waste are stored and monitored for the next centuries, is used as a reference case. There, climatic models anticipate an increase of temperature and seasonality (i.e., dryer Summers and wetter conditions from Fall to Spring) in the next centuries.First, the soils of the CSM are sampled to be characterized. The densities, moisture, grainsize distribution and organic content of the soil are measured. We find that these values are rather homogeneous at the scale of the CSM. Second, a series of experimental rainfall simulations is performed on the CSM soils, focusing of rates and distribution of erosion processes. We simulate rainfall events of decennial, centennial, millennial and decamillennial intensities on 18° slopes, corresponding to the steeper banks of the CSM. Using the capacities of the climatic chambers at the Ecotron Lab in Nemours, France, we further test several soil moistures, i.e., very wet, moderately wet and dry, before simulating rainfall events. Finally, each experiment is repeated several times to assess the “memory” effect of topography on erosion. We quantify erosion by measuring sediment concentrations in run-off water collected at the outlet of the model and using topographic acquisitions performed using photogrammetry.The experimental results are compared with estimations based on the Revised Universal Soil Loss Equation. Some propositions for upscaling, which could be used for assessing hypothetical future increase in soil loss in the CSM, are discussed.
Auteurs, date et publication :
Auteurs Gabriel Portzer , Albert Marchiol , Olivier Stab , Jean-Alain Fleurisson , Samuel Abiven , Simon Chollet , Yara Maalouf , Nicole Khoueiry , Neda Yadari , Neda Yadari
Date : 2024
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Background The availability of soil phosphorus (P) often limits the productivities of wet tropical lowland forests. Little is known, however, about the metabolomic profile of different chemical P compounds with potentially different uses and about the cycling of P and their variability across space under different tree species in highly diverse tropical rainforests.
Results We hypothesised that the different strategies of the competing tree species to retranslocate, mineralise, mobilise, and take up P from the soil would promote distinct soil 31P profiles. We tested this hypothesis by performing a metabolomic analysis of the soils in two rainforests in French Guiana using 31P nuclear magnetic resonance (NMR). We analysed 31P NMR chemical shifts in soil solutions of model P compounds, including inorganic phosphates, orthophosphate mono- and diesters, phosphonates, and organic polyphosphates. The identity of the tree species (growing above the soil samples) explained > 53% of the total variance of the 31P NMR metabolomic profiles of the soils, suggesting species-specific ecological niches and/or species-specific interactions with the soil microbiome and soil trophic web structure and functionality determining the use and production of P compounds. Differences at regional and topographic levels also explained some part of the the total variance of the 31P NMR profiles, although less than the influence of the tree species. Multivariate analyses of soil 31P NMR metabolomics data indicated higher soil concentrations of P biomolecules involved in the active use of P (nucleic acids and molecules involved with energy and anabolism) in soils with lower concentrations of total soil P and higher concentrations of P-storing biomolecules in soils with higher concentrations of total P.
Conclusions The results strongly suggest “niches” of soil P profiles associated with physical gradients, mostly topographic position, and with the specific distribution of species along this gradient, which is associated with species-specific strategies of soil P mineralisation, mobilisation, use, and uptake.
Auteurs, date et publication :
Auteurs Albert Gargallo-Garriga , Jordi Sardans , Joan Llusià , Guille Peguero , Marta Ayala-Roque , Elodie A. Courtois , Clément Stahl , Otmar Urban , Karel Klem , Pau Nolis , Miriam Pérez-Trujillo , Teodor Parella , Andreas Richter , Ivan A. Janssens , Josep Peñuelas
Publication : BMC Plant Biology
Date : 2024
Volume : 24
Issue : 1
Pages : 278
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Remote sensing datasets offer robust approaches for gaining reliable insights into forest ecosystems. Despite numerous studies reviewing forest aboveground biomass estimation using remote sensing approaches, a comprehensive synthesis of synergetic integration methods to map and estimate forest AGB is still needed. This article reviews the integrated remote sensing approaches and discusses significant advances in estimating the AGB from space- and airborne sensors. This review covers the research articles published during 2015–2023 to ascertain recent developments. A total of 98 peer-reviewed journal articles were selected under the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Among the scrutinized studies, 54 were relevant to spaceborne, 22 to airborne, and 22 to space- and airborne datasets. Among the empirical models used, random forest regression model accounted for the most articles (32). The highest number of articles utilizing integrated dataset approaches originated from China (24), followed by the USA (15). Among the space- and airborne datasets, Sentinel-1 and 2, Landsat, GEDI, and Airborne LiDAR datasets were widely employed with parameters that encompassed tree height, canopy cover, and vegetation indices. The results of co-citation analysis were also determined to be relevant to the objectives of this review. This review focuses on dataset integration with empirical models and provides insights into the accuracy and reliability of studies on AGB estimation modeling.
Auteurs, date et publication :
Auteurs Muhammad Nouman Khan , Yumin Tan , Ahmad Ali Gul , Sawaid Abbas , Jiale Wang
Publication : Forests
Date : 2024
Volume : 15
Issue : 6
Pages : 1055
Catégorie(s)
#CNRS #FORET NouraguesRésumé
The interplay between morphological (structures) and behavioral (acts) signals in contest assessment is still poorly understood. During contests, males of the common wall lizard (Podarcis muralis) display both morphological (i.e. static color patches) and behavioral (i.e. raised-body display, foot shakes) traits. We set out to evaluate the role of these putative signals in determining the outcome and intensity of contests by recording agonistic behavior in ten mesocosm enclosures. We find that contests are typically won by males with relatively more black coloration, which are also more aggressive. However, black coloration does not seem to play a role in rival assessment, and behavioral traits are stronger predictors of contest outcome and winner aggression than prior experience, morphology, and coloration. Contest intensity is mainly driven by resource- and self-assessment, with males probably using behavioral threat (raised-body displays) and de-escalation signals (foot shakes) to communicate their willingness to engage/persist in a fight. Our results agree with the view that agonistic signals used during contests are not associated with mutual evaluation of developmentally-fixed attributes, and instead animals monitor each other to ensure that their motivation is matched by their rival. We emphasize the importance of testing the effect of signals on receiver behavior and discuss that social recognition in territorial species may select receivers to neglect potential morphological signals conveying static information on sex, age, or intrinsic quality.
Auteurs, date et publication :
Auteurs Javier Abalos , Guillem Pérez i de Lanuza , Alicia Bartolomé , Océane Liehrmann , Fabien Aubret , Enrique Font
Publication : Behavioral Ecology
Date : 2024
Volume : 35
Issue : 4
Pages : arae045
Catégorie(s)
#CNRS #Metatron terrestreRésumé
Mammal faunas from northern French Guiana (in northeastern Amazonia) and the YavaríUcayali interfluve (in southwestern Amazonia) are the first Amazonian mammal faunas to be comprehensively described in terms of taxonomic composition and community structure. Bats are the most speciose group in each fauna, followed in order of decreasing species richness by rodents, didelphimorphians, carnivorans, xenarthrans or primates, and ungulates. A total of 180 species are known from northern French Guiana and 199 species from the Yavarí-Ucayali interfluve, but an additional 25 species are possibly missing (“pseudoabsent”) from the YavaríUcayali interfluvial inventory; therefore, the increment by which species richness in northeastern Peru exceeds that of northern French Guiana is on the order of 10–25%. Complementarity (dissimilarity) between these faunas is high (79%–89%) for opossums, primates, and rodents, but complementarity is substantially lower for other groups (especially bats, carnivorans, and ungulates), suggesting taxonomic differences in geographic filtering. Most species in both faunas are nocturnal, as might be expected from the abundance of bats, but even among nonflying mammals nocturnal species outnumber diurnal species by about 2:1. Approximately equal numbers of nonflying species in both faunas are arboreal or terrestrial, whereas much smaller numbers are scansorial or semiaquatic; with one possible exception, none is fossorial. Despite such behavioral similarities, these faunas differ in trophic composition and guild membership: substantially more primary consumers are present in the Yavarí-Ucayali interfluve than in northern French Guiana, whereas numbers of secondary consumers and omnivores are similar. Higher primary productivity in western Amazonia, a geomorphologically dynamic landscape with fertile soils and phenologically diverse habitats, could explain faunal differences in both species richness and trophic structure.
Auteurs, date et publication :
Auteurs Robert S. Voss
Publication : American Museum Novitates
Date : 2024
Volume : 2024
Issue : 4019
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Members of the genus Hypoxylon (Ascomycota) are pleomorphic fungi mostly forming conspic uous teleomorphs, consisting of perithecia embedded into stromal tissue, and their morphology has traditionally served for species delineation. However, analysis in tandem with other phenotypic characters, such as chemical and genetic traits, proved to be a more stable predictor of interspecies and intergeneric relationships. During 2014 and 2015, a set of species identified as Hypoxylon were described from the Neotropics, exclusively relying on morphological traits. The secondary meta bolite profiles of their stromata were analysed by HPLC/DAD-ESI-MS, corroborating their classifica tion within Xylariales. Additionally, molecular data for ex-type strains of H. dussii and H. sofaiense were incorporated into an inferred molecular phylogeny of the Hypoxylaceae and allies. Furthermore, a freshly collected specimen from North Carolina was selected as epitype of Sphaeria perforata Schweinitz (syn. Hypoxylon perforatum), as its morphological/chemotaxonomic characters matched those of the holotype. Our findings demonstrate that the secondary metabo lism of Hypoxylon closely correlates with both morphological features and molecular data, serving as a complement for species identification.
Auteurs, date et publication :
Auteurs Marjorie Cedeño-Sanchez , Christopher Lambert , Luis C. Mejia , Sherif S. Ebada , Marc Stadler
Publication : Mycology
Date : 2024
Pages : 1-16
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Tatiana Bush , Jean-Michel Berenger , Hélcio Gil-Santana , Michael Forthman , Rochelle Hoey-Chamberlain , Christiane Weirauch
Publication : American Museum Novitates
Date : 2024
Volume : 2024
Issue : 4025
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Abstract. Forest systems are the main carbon sink after the oceans. However, due to climate change, an alarming number of tree species of the Northern Hemisphere are at risk of migrating northwards or becoming extinct. This is the case for the downy oak (Quercus pubescens), one of the main species constituting the forests close to the Mediterranean Sea in France. Our aim is to retrieve aboveground carbon (AGC) and underground root carbon (UGC) stocks of the downy oak forest at the Observatoire de Haute-Provence (OHP), located about 80 km north of Marseille, in order to provide a baseline against which to assess the effect of climate change on this model species. The study presented here is based on airborne lidar observations performed on May 2012 and field measurements from 2012, 2018 and 2023 in the OHP forest. The OHP forest consists of ∼ 75 % downy oak, which is highly sensitive to global warming. Field measurements indicate minimal changes in tree growth and density between 2012 and 2023, and thus its carbon storage efficiency remains stationary. As retrieved by lidar measurements, tree top heights (TTHs) are mostly between 5 and 12 m, with an uncertainty of around 1 m. The slow evolution of trees at the OHP site makes it appropriate to use lidar data recorded in 2012 to assess the carbon stock trapped in current forest biomass. By coupling allometric laws established from field measurements with lidar observations, we show that the quantities of carbon trapped in aboveground biomass are double those trapped in the root system. Over an area of ∼ 24 ha, mean values of 15 ± 14 tC ha−1 are assessed for the aerial biomass against 8–10 ± 3–7 tC ha−1 for the roots of diameter larger than 1 cm for low and high assessments. These values depend heavily on the height of the sampled trees themselves, as well as on their location on the OHP plateau (smaller trees, 5–6 m) or on the slope (tallest trees, 10–12 m). Using a Monte Carlo approach, the relative uncertainties in AGC were calculated to be of the order of 17 % and 11 % for trees 5–6 m and 10–12 m tall, respectively. For UGC, the relative uncertainties were calculated as 8 % and 5 % for the same tree heights, but the assumptions of the allometric model are associated with biases that can easily reach 100 %. Although the surface footprints are different, we show that there is a reasonable agreement between our airborne lidar measurements and the level 2B (TTH) and (aboveground biomass) operational products of the Global Ecosystem Dynamics Investigation (GEDI) mission on the International Space Station for data acquired between 2019 and 2022.
Auteurs, date et publication :
Auteurs Maëlie Chazette , Patrick Chazette , Ilja M. Reiter , Xiaoxia Shang , Julien Totems , Jean-Philippe Orts , Irène Xueref-Remy , Nicolas Montes
Publication : Biogeosciences
Date : 2024
Volume : 21
Issue : 14
Pages : 3289-3303
Catégorie(s)
#CNRS #FORET O3HPRésumé
Abstract Neotropical forest ecosystems harbour significant biodiversity. To develop effective insect conservation practices, it is important to understand the factors that influence the diversity and population structure of the species. Dispersal, a key determinant of population structure, is well studied in termites nesting in wood, for which it can be influenced by wood transport, or in termites living in urban environments. However, understanding the dispersal of termites whose mobility remains unaffected by wood transport remains understudied. We investigated the dispersal of Embiratermes neotenicus, a soil-feeding species with short dispersal distance, in the Neotropical region, where both intact and degraded forests exist. Using mitochondrial and nuclear data, we analysed genetic diversity, structure and factors contributing to population differentiation in Suriname and French Guiana at multiple scales for 70 colonies. The population in French Guiana is the ancestral population in the region that subsequently expanded. Significant genetic differentiation between populations was observed, with distinct patterns identified in Suriname and French Guiana. The Suriname population showed higher genetic diversity and no subpopulation differentiation, whereas the French Guiana population showed substructure into distinct genetic clusters. Analyses at the scale of all colonies suggest the influence of landscape features, such as the Maroni River, on genetic differentiation. At the local scale, genetic differentiation between colonies increases with forest alteration, even when this does not include major changes in forest cover. Our results highlight the sensitivity of soil-feeding termite populations to habitat change. We argue that multi-scale studies are needed for a comprehensive understanding of genetic patterns, especially for species with short dispersal distances.
Auteurs, date et publication :
Auteurs Damien Gergonne , Chantal Poteaux , Yoan Fourcade , Romain Fougeyrollas , Robert Hanus , David Sillam-Dussès , Virginie Roy
Publication : Insect Conservation and Diversity
Date : 2024
Volume : 17
Issue : 6
Pages : 953-967