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One sixth of Amazonian tree diversity is dependent on river floodplains
No full textInternational audienceAmazonia’s floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region’s floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon’s tree diversity and its function
Toward a coordinated understanding of hydro‐biogeochemical root functions in tropical forests for application in vegetation models
No full textInternational audienceTropical forest root characteristics and resource acquisition strategies are underrepresented in vegetation and global models, hampering the prediction of forest–climate feedbacks for these carbon‐rich ecosystems. Lowland tropical forests often have globally unique combinations of high taxonomic and functional biodiversity, rainfall seasonality, and strongly weathered infertile soils, giving rise to distinct patterns in root traits and functions compared with higher latitude ecosystems. We provide a roadmap for integrating recent advances in our understanding of tropical forest belowground function into vegetation models, focusing on water and nutrient acquisition. We offer comparisons of recent advances in empirical and model understanding of root characteristics that represent important functional processes in tropical forests. We focus on: (1) fine‐root strategies for soil resource exploration, (2) coupling and trade‐offs in fine‐root water vs nutrient acquisition, and (3) aboveground–belowground linkages in plant resource acquisition and use. We suggest avenues for representing these extremely diverse plant communities in computationally manageable and ecologically meaningful groups in models for linked aboveground–belowground hydro‐nutrient functions. Tropical forests are undergoing warming, shifting rainfall regimes, and exacerbation of soil nutrient scarcity caused by elevated atmospheric CO 2 . The accurate model representation of tropical forest functions is crucial for understanding the interactions of this biome with the climate.Las características de las raíces de los bosques tropicales y las estrategias de adquisición de recursos están subrepresentadas en modelos de vegetación, lo que dificulta la predicción del efecto de cambio de clima para estos ecosistemas ricos en carbono. Los bosques tropicales a menudo tienen combinaciones únicas a nivel mundial de alta biodiversidad taxonómica y funcional, estacionalidad de precipitación, y suelos infértiles, dando lugar a patrones distintos en los rasgos y funciones de las raíces en comparación con los ecosistemas de latitudes más altas. Integramos los avances recientes en nuestra comprensión de la función subterránea de los bosques tropicales en modelos de vegetación, centrándonos en la adquisición de agua y nutrientes. Ofrecemos comparaciones de avances recientes en la comprensión empírica y de modelos de las características de las raíces que representan procesos funcionales importantes en los bosques tropicales. Nos centramos en: (1) estrategias de raíces finas para adquisición de recursos del suelo, (2) acoplamiento y compensaciones entre adquisición del agua y de nutrientes, y (3) vínculos entre funciones sobre tierra y debajo del superficie en bosques tropicales. Sugerimos vías para representar estas comunidades de plantas extremadamente diversas en grupos computacionalmente manejables y ecológicamente significativos en modelos. Los bosques tropicales se están calentando, tienen cambios en los regímenes de lluvias, y tienen una exacerbación de la escasez de nutrientes del suelo causada por el elevado CO 2 atmosférico. La representación precisa de las funciones de los bosques tropicales en modelos es crucial para comprender las interacciones de este bioma con el clima
Taxing the carbon content of consumed goods
No full textThis note is concerned by the difference between production-based taxation and consumption-based taxation of CO2 emissions. We focus on the possible discrepancy between a carbon tax paid by the producer and a tax on the carbon content of the consumed good. We want to appraise if and how incentives from consumption-based taxation are pushed down the production chain. Depending on whether the producer takes as fixed the price he receives or the price paid by the consumer (price the producer receives plus the tax on carbon content), we have two different conclusions. This raises a puzzle: which price should be considered as fixed? We show that, if producers are rational, they should take the price paid by the consumer as given, not the price received by the producer. In this case, the tax on carbon content (consumption-based taxation) is equivalent to the standard carbon tax (production-based taxation). Our analysis stresses the importance of the producer’s rationality, as well as the importance of differentiating taxation by the actual carbon content, specific to each producer
Complete sequence and genome characterization of miscanthus virus M, a new betaflexivirus from Miscanthus sp.
No full textInternational audienceA novel betaflexivirus, tentatively named "miscanthus virus M" (MiVM), was isolated from Miscanthus sp. The complete genome of MiVM is 7,388 nt in length (excluding the poly(A) tail). It contains five open reading frames and has a genome organization similar to those of members of the families Alphaflexiviridae and Betaflexiviridae (subfamily Quinvirinae). The amino acid sequences of both the replicase and coat protein shared less than 45% identity with the corresponding sequences of members of either family. Phylogenetic analysis confirmed that MiVM belongs to the family Betaflexiviridae and subfamily Quinvirinae but it was too distantly related to be included in any currently recognized genus in this family. We therefore propose that miscanthus virus M represents a new species and a new genus in the family Betaflexiviridae
Biochar as Soil Amendment in Climate-Smart Agriculture: Opportunities, Future Prospects, and Challenges
No full textInternational audienceThere appears to be an increasing demand for quality food and fodder to ensure environmental safety. Although chemical fertilizers and pesticides are widely used to increase crop yield and plant protection, the unauthorized and injudicious use of chemicals negatively affects native flora and fauna and depletes natural soil fertility, culminating in quality loss, climate crisis, and global warming. Recently, there has been a lot of focus on using biochar to improve soil health, mitigate soil degradation, and control soil and water pollution because biochar restores ecosystems and enhances soil quality. Biochar is a solid, carbon-rich material with a high surface area and improved nutrient content that exhibits slow nutrient release properties obtained through the pyrolysis of various biochar-based environmental materials. Sustainable biochar release in the soil can improve plant growth through nutrient use efficiencies, enhancing beneficial plant-microbe interactions, and plant protection. The current review summarizes the properties and cost-effective production technologies of quality biochar, sustainable application, action mechanisms for improving soil properties, and prominent plant-microbe interactions for enhanced plant growth and survival under climate-smart agriculture. Biochar's agronomic potential in the soil is affected by physical and chemical properties, such as surface area, particle density, and pore size distribution, as well as pH, electrical conductivity, total and plant-available concentrations of carbon, nitrogen, potassium, and phosphorus, cation exchange capacity, and certain minor nutrients. Additionally, the essential requirements of healthy soil and associated attributes of good agricultural practices are addressed, along with the key benefits, limitations, and opportunities of biochar application for enhancing sustainability in agriculture
Ce que les comportements sur le terrain nous disent des chercheurs : une expérimentation réflexive menée en Cévennes
No full textInternational audienceLa crise écologique bouscule les savoirs scientifiques établis, elle requiert à ce titre une plusgrande réflexivité de la part des chercheurs pour ce qui est de leur rapport distancié au terrain.La question se pose de savoir comment favoriser une interconnexion qui leur permettrait de serendre attentif aux singularités des territoires. Souhaitant contribuer à ce mouvement, nousavons organisé une « sortie de terrain » avec des hydrologues pour analyser leur posture et leurspratiques. Nos résultats montrent que, s’il existe plusieurs rapports au terrain, ceux-ci ne sontjamais tout à fait dénués d’engagement sensible, corporel et esthétique, quand bien même cesengagements sont habituellement tus. Nous questionnons les postures épistémiques deschercheurs embarqués dans notre expérimentation et discutons des possibilités nouvelles quis’offrent pour le dialogue interdisciplinaire.The ecological crisis is shaking up established scientific knowledge, and as such requires greaterreflexivity on the part of researchers in terms of their distanced relationship with the field. Thequestion is how to encourage an interconnection that will enable us to be attentive to thesingularities of the territories. With a view to contributing to this movement, we organised a'field trip' with hydrologists to analyse their attitudes and practices. Our results show that, whilethere are many different relationships to the field, these are never entirely devoid of sensitive,physical and aesthetic engagement, even if these commitments are usually kept quiet. Wequestion the epistemic cultures of the researchers involved in our experiment and discuss thenew possibilities for interdisciplinary dialogu
Biological valorization of urban solid biowaste: A study among circular bioeconomy start-ups in France
No full textInternational audienc
Functional–Structural Plant Model “GreenLab”: A State-of-the-Art Review
No full textInternational audienceIt is crucial to assess the impact of climate change on crop productivity and sustainability for the development of effective adaptation measures. Crop models are essential for quantifying this impact on crop yields. To better express crops’ intrinsic growth and development patterns and their plasticity under different environmental conditions, the functional–structural plant model (FSPM) “GreenLab” has been developed. GreenLab is an organ-level model that can describe the intrinsic growth and development patterns of plants based on mathematical expressions without considering the influence of environmental factors, and then simulate the growth and development of plants in expressing plant plasticity under different environmental conditions. Moreover, the distinctive feature of GreenLab lies in its ability to compute model source–sink parameters affecting biomass production and allocation based on measured plant data. Over the past two decades, the GreenLab model has undergone continuous development, incorporating novel modeling methods and techniques, including the dual-scale automaton, substructure methods, the inverse of source–sink parameters, crown analysis, organic series, potential structure, and parameter optimization techniques. This paper reviews the development history, the basic concepts, main theories, characteristics, and applications of the GreenLab model. Additionally, we introduce the software tools that implement the GreenLab model. Last, we discuss the perspectives and directions for the GreenLab model’s future development
Radiometric landscape: a new conceptual framework and operational approach for landscape characterisation and mapping
No full textInternational audienc
A Late Pleistocene coastal ecosystem in French Guiana was hyperdiverse relative to today
No full textInternational audienceWarmer temperatures and higher sea level than today characterized the Last Interglacial, interval [Pleistocene, 128 to 116 thousand years ago (ka)]. This period is a remarkable deep-time analog for temperature and sea-level conditions as projected for 2100 AD, yet there has been no evidence of fossil assemblages in the equatorial Atlantic. Here, we report foraminifer, metazoan (mollusks, bony fish, bryozoans, decapods, and sharks among others), and plant communities of coastal tropical marine and mangrove affinities, dating precisely from a ca. 130 to 115 ka time interval near the Equator, at Kourou, in French Guiana. These communities include ca. 230 recent species, some being endangered today and/or first recorded as fossils. The hyperdiverse Kourou mollusk assemblage suggests stronger affinities between Guianese and Caribbean coastal waters by the Last Interglacial than today, questioning the structuring role of the Amazon Plume on tropical Western Atlantic communities at the time. Grassland-dominated pollen, phytoliths, and charcoals from younger deposits in the same sections attest to a marine retreat and dryer conditions during the onset of the last glacial (ca. 110 to 50 ka), with a savanna-dominated landscape and episodes of fire. Charcoals from the last millennia suggest human presence in a mosaic of modern-like continental habitats. Our results provide key information about the ecology and biogeography of pristine Pleistocene tropical coastal ecosystems, especially relevant regarding the—widely anthropogenic— ongoing global warming