Résumé
The upcoming BIOMASS mission will provide P-band repeat-pass PolInSAR data from space for the improved mapping of global biomass. PolInSAR technique has been widely validated with the potential to invert forest height and estimate forest aboveground biomass (AGB). However, the robustness of PolInSAR-based AGB estimation across different sites still lacks full evaluation, especially for those with a varied forest type, heterogeneity (varied growth ratio between cover and height), and topographic relief. In this study, we concentrated on backscatter decomposition and forest height inversion, and developed a robust AGB estimation method that can be applied to different sites. Two dense and closed tropical forest sites (Paracou and Nouragues) and one open and heterogeneous boreal forest site (Krycklan) were selected as the study areas, and the corresponding airborne PolInSAR, LiDAR, and ground measured AGB data were used for validation and analysis. Results show that ground backscatter has the strongest correlation with AGB in boreal forests, but this correlation cannot be transferred to the tropical forests. Only canopy volume backscatter is almost free from topographic influence, and its relationship with AGB across three sites can be formulated using one exponential equation, producing the best estimation accuracy, with R2 of 0.79 and RMSE of 61.5 tons/ha (relative RMSE of 20.0 %). Multi-baseline PolInSAR retrieved forest height with little bias in spite of the presence of temporal decorrelation. One power equation can be used to correlate PolInSAR forest height with AGB across three different sites, and LOO (leave-one-out) validation shows the R2 of 0.85 and RMSE of 51.8 tons/ha (relative RMSE of 16.9 %). However, the RVoG-inverted PolInSAR FH was found to mainly represent the top forest height for open and heterogeneous forests, which means PolInSAR FH (forest height) lacks consideration for forest horizontal structure (e.g. forest density). In contrast, volume backscatter better captured forest density, and the proposed AGB model that combines PolInSAR FH and volume backscatter further improved the AGB estimation accuracy, especially for open forests: the plot-scale validation from all three sites shows R2 was improved from 0.79 (volume backscatter) and 0.85 (PolInSAR FH) to 0.89, and RMSE decreased from 61.5 and 51.8 to 45.2 (relative RMSE of 14.7 %) tons/ha; for region-scale validation, R2 was improved from 0.77 and 0.83 to 0.89, and RMSE decreased from 64.2 (relative RMSE of 39.0 %) and 54.5 (34.5 %) to 48.1 (29.4 %) tons/ha.
Auteurs, date et publication :
Auteurs Zhanmang Liao , Binbin He , Yue Shi
Publication : International Journal of Applied Earth Observation and Geoinformation
Date : 2022
Volume : 115
Pages : 103088
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
The World Register of Marine species (WoRMS) has been established for a decade. The early history of the database involved compilation of existing global and regional species registers. This aggregation, combined with changes to data types and the changing needs of WoRMS users, has resulted in an evolution of data-entry consistency over time. With the task of aggregating the accepted species names for all marine species approaching completion, our focus has shifted to improving the consistency and quality of data held while keeping pace with the addition of > 2000 new marine species described annually. This paper defines priorities and longer-term aims that promote standardisation within and interoperability among biodiversity databases, provides editors with further information on how to input nomenclatural data in a standardised way and clarifies for users of WoRMS how and why names are represented as they are. We 1) explain the categories of names included; 2) list standard reasons used to explain why a name is considered ‘unaccepted’ or ‘uncertain’; 3) present and explain the more difficult situations encountered; 4) describe categories of sources and notes linked to a taxon; and 5) recommend how type material, type locality and environmental information should be entered.
Auteurs, date et publication :
Auteurs Tammy Horton , Serge Gofas , Andreas Kroh , Gary C. B. Poore , Geoffrey Read , Gary Rosenberg , Sabine Stöhr , Nicolas Bailly , Nicole Boury-Esnault , Simone N. Brandão , Mark J. Costello , Wim Decock , Stefanie Dekeyzer , Francisco Hernandez , Jan Mees , Gustav Paulay , Leen Vandepitte , Bart Vanhoorne , Sofie Vranken
Publication : European Journal of Taxonomy
Date : 2017
Issue : 389
Catégorie(s)
#CNRS #FORET O3HPAuteurs, date et publication :
Auteurs Fabian Jörg Fischer , Isabelle Maréchaux , Jérôme Chave
Publication : New Phytologist
Date : 2025
Volume : 223
Issue : 3
Pages : 1159-1165
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Global changes will modify future nutrient availability with implications for grassland biogeochemistry. Soil organic matter (SOM) is central to grasslands for both provision of nutrients and climate mitigation through carbon (C) storage. While we know that C and nitrogen (N) in SOM can be influenced by greater nutrient availability, we lack understanding of nutrient effects on C and N coupling and stability in soil. Different SOM fractions have different functional relevance and mean residence times, i.e., mineral-associated organic matter (MAOM) has a higher mean residence time than particulate organic matter (POM). By separating effects of nutrient supply on the different SOM fractions, we can better evaluate changes in soil C and N coupling and stability and associated mechanisms. To this end, we studied responses of C and N ratios and distributions across POM and MAOM to 6–10 years of N, phosphorus (P), potassium and micronutrients (K+µ), and combined NPK+µ additions at 11 grassland sites spanning 3 continents and globally relevant environmental gradients in climate, plant growth, soil texture, and nutrient availability. We found addition of N and NPK+µ generally reduced C:N in MAOM and POM. However, at low fertility and at warm, sandy sites, nutrient addition promoted higher MAOM and POM C:N, respectively. Addition of NPK+µ also promoted C storage in POM relative to MAOM, and this was consistent across sites. Our results suggest that addition of macro- and micronutrients consistently decrease SOM stabilization, whereas responses of soil C:N stoichiometry were contingent on SOM fraction and environmental conditions.
Auteurs, date et publication :
Auteurs Katherine S. Rocci , Kaydee S. Barker , Eric W. Seabloom , Elizabeth T. Borer , Sarah E. Hobbie , Jonathan D. Bakker , Andrew S. MacDougall , Rebecca L. McCulley , Joslin L. Moore , Xavier Raynaud , Carly J. Stevens , M. Francesca Cotrufo
Publication : Biogeochemistry
Date : 2022
Volume : 159
Issue : 3
Pages : 353-370
Catégorie(s)
#ANR-Citation #CEREEP #CNRS #ENSRésumé
Transparency is one of the most intuitive forms of camouflage, where predators see straight through their prey as if it were not there. Glass frogs are a classic example of animal transparency and are well known for their transparent ventral skin, through which the internal organs can be clearly seen. The efficacy of transparency on land, however, has been controversial. We found that under natural conditions these frogs are better described as translucent and that translucency acts as modifiable camouflage. Differences in the degree of translucency over the frog act to disguise the frog’s outline and highlight the potential of “edge diffusion” as a form of camouflage, making glass frog camouflage distinct from both transparency and active color change.Camouflage patterns prevent detection and/or recognition by matching the background, disrupting edges, or mimicking particular background features. In variable habitats, however, a single pattern cannot match all available sites all of the time, and efficacy may therefore be reduced. Active color change provides an alternative where coloration can be altered to match local conditions, but again efficacy may be limited by the speed of change and range of patterns available. Transparency, on the other hand, creates high-fidelity camouflage that changes instantaneously to match any substrate but is potentially compromised in terrestrial environments where image distortion may be more obvious than in water. Glass frogs are one example of terrestrial transparency and are well known for their transparent ventral skin through which their bones, intestines, and beating hearts can be seen. However, sparse dorsal pigmentation means that these frogs are better described as translucent. To investigate whether this imperfect transparency acts as camouflage, we used in situ behavioral trials, visual modeling, and laboratory psychophysics. We found that the perceived luminance of the frogs changed depending on the immediate background, lowering detectability and increasing survival when compared to opaque frogs. Moreover, this change was greatest for the legs, which surround the body at rest and create a diffuse transition from background to frog luminance rather than a sharp, highly salient edge. This passive change in luminance, without significant modification of hue, suggests a camouflage strategy, “edge diffusion,” distinct from both transparency and active color change.
Auteurs, date et publication :
Auteurs James B. Barnett , Constantine Michalis , Hannah M. Anderson , Brendan L. McEwen , Justin Yeager , Jonathan N. Pruitt , Nicholas E. Scott-Samuel , Innes C. Cuthill
Publication : Proceedings of the National Academy of Sciences
Date : 2025
Volume : 117
Issue : 23
Pages : 12885
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Baptiste Hulin , Samuel Abiven
Date : 2023
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENSRésumé
Eutrophication and climate change have increased the frequency of hypoxic conditions in the
hypolimnia of lakes and reservoirs worldwide. Hypoxia can alter zooplankton migration from
vertical to horizontal because zooplankton require oxygen for respiration, and thus may be forced
to littoral refuge during the day. Fish communities can also affect zooplankton migration as well
as zooplankton community composition and size structure. However, the interaction of fish
communities and hypoxia on zooplankton migration has not been studied. We tested the
hypothesis that zooplankton exhibit more extensive (greater magnitude) vertical and horizontal
migration when piscivores are rare than when they are abundant, and also under hypoxic vs. oxic
hypolimnetic conditions. We sampled zooplankton and other environmental variables across six
consecutive days and nights during summer 2019 in a 16-lake experimental system, as part of
AQUACOSM. Half of the artificial lakes received a fertilization treatment with N and P
(eutrophic lakes with hypolimnetic hypoxia), and lakes were manipulated in order to enrich half
of them with European Perch (potentially piscivorous), and to reduce perch individuals in the
other lakes (all lakes had planktivorous Roach). Zooplankton were sampled in the epilimnion and
hypolimnion of the open water habitat and just outside and inside of the vegetated littoral zone.
We will report on the effects of fish communities and dissolved oxygen conditions on
zooplankton density and biomass in littoral vs. pelagic zones, and their diel vertical and
horizontal movements.
Auteurs, date et publication :
Auteurs J. P. Doubek , R. J. Chapina , S. Fiorini , S. K. Goldfarb , G. Lacroix , H. L. Wander , J. D. Stockwell
Date : 2025
Catégorie(s)
#⛔ No DOI found #CNRS #ENS #PLANAQUARésumé
Zooplankton perform daily migrations between pelagic surface waters, where they feed at night, and either deeper waters (diel vertical migration, DVM) or littoral areas (diel horizontal migration, DHM), where they avoid visual predators or damaging ultraviolet radiation during the day. Diel migration patterns can change based on environmental stressors and food web perturbations, and these behavioral changes have implications for ecological processes in lakes. We hypothesized that crustacean DVM decreases and DHM increases in ponds with hypoxic bottom waters and that DVM and DHM are more extensive with higher planktivory by fish. To address our hypotheses, we assessed crustacean and rotifer community composition and daily migration behavior across pelagic and littoral zones of 16 shallow experimental ponds with differing dissolved oxygen concentrations and planktivorous fish densities in August 2019. Community metrics were driven by habitat, with littoral samples containing a higher taxa richness and diversity of crustaceans and rotifers compared to pelagic samples. DVM and DHM behaviors varied widely based on taxonomic groups. Hypoxia and planktivory had minor effects on zooplankton community metrics and migration behaviors. Our findings contribute to the body of knowledge regarding interactive impacts of hypoxia and planktivory on zooplankton communities and behavioral dynamics in shallow ponds.
Auteurs, date et publication :
Auteurs Anna G. Schmidt , Isabel M. Anderson , Rosalie Bruel , Rosaura J. Chapina , Jonathan P. Doubek , Sarah Fiorini , Sadye K. Goldfarb , Gérard Lacroix , Heather L. Wander , Savannah Zigic , Jason D. Stockwell
Publication : Hydrobiologia
Date : 2025
Volume : 852
Issue : 10
Pages : 2687-2707
Catégorie(s)
#CNRS #ENS #PLANAQUARésumé
Under higher atmospheric CO2 concentrations, increases in soil moisture and, hence in terrestrial-aquatic carbon transfer are probable. In a coupled terrestrial-aquatic experiment we examined the direct (e.g. through changes in the CO2 water concentration) and indirect (e.g. through changes in the quality and quantity of soil leachates) effects of elevated CO2 on a lake microbial community. The incubation of soils under elevated CO2 resulted in an increase in the volume of leachates and in both chromophoric dissolved organic matter (CDOM) absorption and fluorescence in leachate. When this leachate was added to lake water during a 3-day aquatic incubation, we observed negative direct effects of elevated CO2 on photosynthetic microorganism abundance and a positive, indirect effect on heterotrophic microbial community cell abundances. We also observed a strong, indirect impact on the functional structure of the community with higher metabolic capacities under elevated CO2 along with a significant direct effect on CDOM absorption. All of these changes point to a shift towards heterotrophic processes in the aquatic compartment under higher atmospheric CO2 concentrations.
Auteurs, date et publication :
Auteurs Emma Rochelle-Newall , Audrey Niboyet , Ludwig Jardiller , Sarah Fiorini , Simon Chollet , Mathieu Llavata , Elisa de Santis , Sébastien Barot , Gérard Lacroix
Publication : Aquatic Sciences
Date : 2018
Volume : 80
Issue : 3
Pages : 27
Catégorie(s)
#ANR-Citation #CNRS #Ecotron IleDeFrance #ENSRésumé
Studies of ant biodiversity are important to understand their group better, as well as to extend our knowledge on the evolution of their associated organisms. Host-associated microbial communities, and particularly bacterial communities, are shaped by different host factors such as habitat, diet, and phylogeny. Here, we studied the structures of bacterial and microbial eukaryote communities associated with Amazonian ants collected from two habitats: the rainforest and the city. We collected 38 ant species covering a large taxonomic range, and we used 16S rRNA and 18S rRNA amplicon sequencing to study the impact of the host’s ecological and phylogenetic factors on their microbial communities. Our results show that (1) habitat does not structure ant microbial communities, (2) ant diet and nesting mode impact bacterial communities, while only nesting mode structures microbial eukaryote communities, and (3) microbial diversity is not correlated with host phylogeny, although several ant genera have conserved bacterial communities. As we continue to uncover the diversity and function of insect-associated microbes, this work explores how host ecology and evolutionary history shape ant microbial communities.
Auteurs, date et publication :
Auteurs Anaïs Chanson , Corrie S. Moreau , Christophe Duplais
Publication : Diversity
Date : 2023
Volume : 15
Issue : 2
Pages : 126