Résumé

Background  The genus Camillea was created in 1849 from collections made in French Guiana with eight species included. Numerous species assigned to Camillea were subsequently discovered, especially in the forests of the Amazon basin, but new discoveries have not been reported from French Guiana since 1849. Recent fieldwork in French Guiana has begun to fill this gap by identifying five new species, most of which were collected in the vicinity of Saül village.
Results  Based on macro- and micromorphological study of their stromata, including SEM images of ascospore wall ornamentation, five new species were recognized, including C. cribellum, C. heterostomoides, C. nitida, C. rogersii and C. saulensis. Cultures could be obtained for C. heterostomoides and C. rogersii, and ITS and LSU sequences were obtained for all of the five new species. Camillea heterostoma and its variety microspora were shown to be conspecific. Provisional molecular phylogenetic analyses support the possible reinstatement of Hypoxylon melanaspis, currently regarded as merely an applanate form of C. leprieurii.
Conclusion  The current study is based on a relatively limited fieldwork in its duration and sampling area but was able to substantially increase the number of Camillea species known from French Guiana. This augurs an exceptional and still unknown diversity of the genus in this area and by extension in the adjacent neotropical forests.

Auteurs, date et publication :

Auteurs Jacques Fournier , Huei-Mei Hsieh , Christian Lechat , Yu-Ming Ju , Delphine Chaduli , Anne Favel

Publication : Botanical Studies

Date : 2023

Volume : 64

Issue : 1

Pages : 31

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

The previously monotypic geometrid genus Achagua (Ennominae: Nacophorini) is reviewed following the discovery of three undescribed species. New species are as follows: A. cooperae n. sp. described from Costa Rica, A. magna n. sp. described from Ecuador, Peru, and Bolivia; and Achagua velata n. sp. described from French Guiana. Available COI barcode data is briefly reviewed, and adult and genitalic illustrations are provided for each of the four known species.

Auteurs, date et publication :

Auteurs Tanner A. Matson

Publication : Zootaxa

Date : 2023

Volume : 5352

Issue : 4

Pages : 565-576

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

Increasing soil organic carbon contents contributes to global climate change mitigation. However, new plant inputs can enhance the mineralization of native soil organic carbon by the positive priming effect, which may counterbalance the sequestration of new carbon. Here we use soils from a 20 year chronosequence of inverted pasture soils (reciprocal translocation of topsoil and subsoil to >1 m) to study the dynamics of soil organic carbon in topsoils and subsoils. We evaluated the root-induced priming effect by differentiating native soil organic carbon from 13C root-derived carbon in a 6 month incubation experiment. We found that the addition of fresh root-derived carbon caused positive priming of native soil organic carbon in new topsoils (109 ± 27% additional respiration compared with controls without roots) and subsoils (331 ± 84%) after inversion. This effect was temporary for new topsoils as they accumulated soil organic carbon and adapted to high carbon inputs within a few years, leading to no priming in the long term. In contrast, buried topsoils became more sensitive to root carbon inputs over time, demonstrating how the legacy of high carbon inputs mediates the magnitude of priming (50% to 390% after 20 years of inversion). Overall, carbon losses with priming never exceeded new root-derived carbon inputs. We conclude that priming is a temporary reaction to additional carbon, which attenuates when soils adapt to high carbon inputs within a few years to decades.

Auteurs, date et publication :

Auteurs Marcus Schiedung , Axel Don , Michael H. Beare , Samuel Abiven

Publication : Nature Geoscience

Date : 2023

Volume : 16

Issue : 10

Pages : 909-914

Catégorie(s)

#CNRS #Ecotron IleDeFrance #ENS

Résumé

Earthworms are known to stimulate soil greenhouse gas (GHG) emissions, but the majority of previous studies have used simplified model systems or lacked continuous high-frequency measurements. To address this, we conducted a 2-year study using large lysimeters (5 m2 area and 1.5 m soil depth) in an ecotron facility, continuously measuring ecosystem-level CO2, N2O, and H2O fluxes. We investigated the impact of endogeic and anecic earthworms on GHG emissions and ecosystem water use efficiency (WUE) in a simulated agricultural setting. Although we observed transient stimulations of carbon fluxes in the presence of earthworms, cumulative fluxes over the study indicated no significant increase in CO2 emissions. Endogeic earthworms reduced N2O emissions during the wheat culture (− 44.6%), but this effect was not sustained throughout the experiment. No consistent effects on ecosystem evapotranspiration or WUE were found. Our study suggests that earthworms do not significantly contribute to GHG emissions over a two-year period in experimental conditions that mimic an agricultural setting. These findings highlight the need for realistic experiments and continuous GHG measurements.

Auteurs, date et publication :

Auteurs Oswaldo Forey , Joana Sauze , Clément Piel , Emmanuel S. Gritti , Sébastien Devidal , Abdelaziz Faez , Olivier Ravel , Johanne Nahmani , Laly Rouch , Manuel Blouin , Guénola Pérès , Yvan Capowiez , Jacques Roy , Alexandru Milcu

Publication : Scientific Reports

Date : 2023

Volume : 13

Issue : 1

Pages : 21920

Catégorie(s)

#ANR-Citation #CNRS #Ecotron de Montpellier

Résumé

Despite the potential of subsoil carbon (C) to buffer or amplify climate change impacts, how fresh C and nutrients interact to control microorganismal effects on the C balance in deep soil horizons has yet to be determined. In this study, we aimed to estimate the impact of fresh C input at different soil depths on soil microbial activity. To conduct this study, Mediterranean soils from 3 layers (0–20, 20–50 and 50–100 cm of depth) were incubated over 28 days. Carbon and nutrient fluxes were measured after the addition of an amount of C equivalent to the postharvest root litter derived-C of a barley crop (4.3 atom% 13C), with and without nitrogen and phosphorus supply. We found that the microbial mineralization was C limited in the topsoil, while C and N colimited in the subsoil. These variations in stoichiometric constraints along the soil profile induced different microbial responses to C and/or nutrient addition. A stronger priming effect was observed in the topsoil than in the subsoil, and the sole C addition induced a negative C balance. Conversely, subsoil showed a positive C balance following fresh C addition, changing to critical soil C losses when nutrients were supplied with C. Our results show that fresh C input to subsoil (e.g., through deep-rooting crops) might foster soil C sequestration, but this positive effect can be reversed if such C inputs are combined with high nutrient availability (e.g., through fertilization), alleviating microbial limitation at depth.

Auteurs, date et publication :

Auteurs Lorène Siegwart , Gabin Piton , Christophe Jourdan , Clément Piel , Joana Sauze , Soh Sugihara , Isabelle Bertrand

Publication : Geoderma

Date : 2023

Volume : 440

Pages : 116729

Catégorie(s)

#CNRS #Ecotron de Montpellier

Résumé

Peatlands are an important carbon (C) reservoir storing one-third of global soil organic carbon (SOC), but little is known about the fate of these C stocks under climate change. Here, we examine the impact of warming and elevated atmospheric CO2 concentration (eCO2) on the molecular composition of SOC to infer SOC sources (microbe-, plant- and fire-derived) and stability in a boreal peatland. We show that while warming alone decreased plant- and microbe-derived SOC due to enhanced decomposition, warming combined with eCO2 increased plant-derived SOC compounds. We further observed increasing root-derived inputs (suberin) and declining leaf/needle-derived inputs (cutin) into SOC under warming and eCO2. The decline in SOC compounds with warming and gains from new root-derived C under eCO2, suggest that warming and eCO2 may shift peatland C budget towards pools with faster turnover. Together, our results indicate that climate change may increase inputs and enhance decomposition of SOC potentially destabilising C storage in peatlands.

Auteurs, date et publication :

Auteurs Nicholas O. E. Ofiti , Michael W. I. Schmidt , Samuel Abiven , Paul J. Hanson , Colleen M. Iversen , Rachel M. Wilson , Joel E. Kostka , Guido L. B. Wiesenberg , Avni Malhotra

Publication : Nature Communications

Date : 2023

Volume : 14

Issue : 1

Pages : 7533

Catégorie(s)

#CNRS #Ecotron IleDeFrance #ENS

Auteurs, date et publication :

Auteurs Jérémie Lapèze , Carlos Lopez-Vaamonde

Publication : Faunitaxys

Date : 2025

Volume : 12

Issue : 3

Pages : 1-23

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

The biodiversity of tropical rainforest is difficult to assess. Yet, its estimation is necessary for conservation purposes, to evaluate our level of knowledge and the risks faced by the forest in relation to global change. Our contribution is to estimate the regional richness of tree species from local but widely spread inventories. We reviewed the methods available, which are nonparametric estimators based on abundance or incidence data, log-series extrapolation and the universal species-area relationship based on maximum entropy. Appropriate methods depend on the scale considered. Harte’s self-similarity model is suitable at the regional scale, while the log-series extrapolation is not. GuyaDiv is a network of forest plots installed over the whole territory of French Guiana, where trees over 10 cm DBH are identified. We used its information (1315 species censused in 68 one-hectare plots) to estimate the exponent of the species-area relationship, assuming Arrhenius’s power law. We could then extrapolate the number of species from three local, wide inventories (over 2.5 km2). We evaluated the number of tree species around 2200 over the territory.

Auteurs, date et publication :

Auteurs Eric Marcon , Ariane Mirabel , Jean-François Molino , Daniel Sabatier

Publication : Journal of Tropical Ecology

Date : 2025

Volume : 40

Pages : e11

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

The genus Tamphana Schaus, 1892 is revised. The transfer of Tamphana from Bombycidae to Apatelodidae is confirmed. The study, based on examination of habitus, genitalia, and barcoding, leads to the separation of the various species currently placed within Tamphana into two distinct genera. Examination of genitalia of specimens supposedly belonging to the species T. marmorea Schaus, 1892 revealed strikingly different characters leading to description of nine new species: T. awa n. sp. from Maranhão, Brazil, T. ampliata n. sp. from Costa Rica, Panama, Venezuela and Ecuador, T. picobonitensis n. sp. from Honduras and Costa Rica, T. furtadoi n. sp. from Mato Grosso, Brazil, T. lauriei n. sp. from Belize, T. lucifer n. sp. from French Guiana, T. paranensis n. sp. from Brazil (Minas Gerais and Paraná), T. tikuna n. sp. from Colombia, Peru and Brazil (Amazonas), T. tripertita n. sp. from French Guiana. The adults and genitalia of all the new species are figured. A lectotype for Tamphana marmorea is here designated and figured. In the genus Tuyvae Orlandin, Piovesan & Carneiro, 2024, recently published, to the two already described species: Tuyvae maoma (Schaus, 1920) and Tuyvae orion (Dognin, 1916), two additional new species are described: Tuyvae douglasboyesi n. sp. from Colombia and Tuyvae carabaya n. sp. from Peru. A lectotype for Tuyvae orion is here designated and figured.

Auteurs, date et publication :

Auteurs Daniel Herbin , Alessandro Giusti , Carlos G. C. Mielke

Publication : Faunitaxys

Date : 2025

Volume : 12

Issue : 61

Pages : 1-31

Catégorie(s)

#CNRS #FORET Nouragues

Résumé

Cleistes rosea and 10 other taxa comprise a complex widely distributed in various open vegetation types from eastern South America to Panama. The taxonomic identity of most of these taxa is unclear and their relationships with C. rosea have never been satisfactorily discussed or tested. Here, we employ molecular phylogenetics, morphometrics and morphological, ecological and geographic distribution data to investigate the relationships and taxonomy of Cleistes rosea and related species. Our results confirm that Cleistes rosea and Cleistes castaneoides are sister species and although highly similar in general floral morphology, they differ in vegetative characters, distribution, habitat, floral scent, and lip characters. Both species show local variations regarding floral characters, particularly the flower colour, and such differences were used here to delimit infraspecific taxa within the C. rosea/C. castaneoides clade. While C. rosea var. guianensis var. nov. is restricted to French Guiana, and C. rosea var. buenaventurae stat. & comb. nov. is restricted to low altitudes on the western side of the Cordillera Occidental in the Choco region of Colombia, C. castaneoides var. castaneoides and C. castaneoides var. augusta comb. nov. are sympatric throughout their distribution. Cleistes abdita, formerly known as C. rosea f. pallida, is similar to C. castaneoides but distinguished by the smaller flowers and restricted distribution to Amazonian savannas. Cleistes rosea is distributed throughout the north of the Andes and northern South America. In turn, C. castaneoides occurs mainly in South-eastern and Central-western Brazil. Still, the distribution of these three species overlaps in the Guiana Shield, where the differentiation between them is less evident. Our results provide evidence of the plasticity of the floral morphology of Cleistes, especially the lip, and highlight that hitherto neglected characters, such as vegetative morphology, habitat, and floral scent, are particularly informative for the characterization of species and taxonomy of the genus.

Auteurs, date et publication :

Auteurs João Aguiar Nogueira Batista , Cristian Castro , Aurélien Sambin , Gabriela Cruz-Lustre , Emerson Ricardo Pansarin

Publication : Systematics and Biodiversity

Date : 2023

Volume : 21

Issue : 1

Pages : 2207575

Catégorie(s)

#CNRS #FORET Nouragues