Background: Plant functional traits co-vary along strategy spectra, thereby defining trade-offs for resource acquisition and utilization amongst other processes. A main objective of plant ecology is ...to quantify the correlations among traits and ask why some of them are sufficiently closely coordinated to form a single axis of functional specialization. However, due to trait co-variations in nature, it is difficult to propose a mechanistic and causal explanation for the origin of trade-offs among traits observed at both intra- and inter-specific level. Methodology/Principal Findings: Using the GEMINI individual-centered model which coordinates physiological and morphological processes, we investigated with 12 grass species the consequences of deliberately decoupling variation of leaf traits (specific leaf area, leaf lifespan) and plant stature (height and tiller number) on plant growth and phenotypic variability. For all species under both high and low N supplies, simulated trait values maximizing plant growth in monocultures matched observed trait values. Moreover, at the intraspecific level, plastic trait responses to N addition predicted by the model were in close agreement with observed trait responses. In a 4 D trait space, our modeling approach highlighted that the unique trait combination maximizing plant growth under a given environmental condition was determined by a coordination of leaf, root and whole plant processes that tended to co-, limit the acquisition and use of carbon and of nitrogen. Conclusion/Significance: Our study provides a mechanistic explanation for the origin of trade-offs between plant functional traits and further predicts plasticity in plant traits in response to environmental changes. In a multidimensional trait space, regions occupied by current plant species can therefore be viewed as adaptive corridors where trait combinations minimize allometric and physiological constraints from the organ to the whole plant levels. The regions outside this corridor are empty because of inferior plant performance.
Demonstrating the functional role of traits for plant performance: a mechanistic modeling approach Gross , Nicolas (INRA , Clermont-Ferrand (France). UR 0874 Unité de recherche sur l'Ecosystème Prairial ); Maire , Vincent(collaborateur) (INRA , Clermont-Ferrand (France). UR 0874 Unité de recherche sur l'Ecosystème Prairial ); Martin , Raphaël(collaborateur) (INRA , Clermont-Ferrand (France). UR 0874 Unité de recherche sur l'Ecosystème Prairial ) ...
2008
Conference Proceeding
La mise au point d'un modèle mécaniste permettant de simuler le fonctionnement de prairies à flore complexe est un projet ambitieux, permis par la synthèse de divers travaux de recherche en ...agronomie, zootechnie et écologie fonctionnelle. Les applications de ce type de modèle concernent la gestion des prairies, le rôle de la biodiversité pour les services écologiques des prairies et la simulation des impacts du changement climatique. Le projet DISCOVER étudie les relations entre la biodiversité et le fonctionnement de couverts prairiaux à flore complexe dans des expériences de longue durée, ce qui permet de paramétrer et d'évaluer un modèle mécaniste (GEMINI) lequel simule la dynamique des espèces végétales et ses conséquences pour la production végétale, la qualité de l'herbe et le fonctionnement du sol. Pour des plantes en compétition au sein du couvert, GEMINI calcule la capture de lumière et d'azote, ainsi que la morphologie des parties aériennes et des racines. Les effets du nombre et du type d'espèce pour la productivité de la prairie ont été simulés, en tenant compte de la plasticité de forme et de fonction des plantes. Des exemples de résultats sont donnés.
Within the framework of the 'DISCOVER' project (ANR Bio-diversity), the relationships between the bio-diversity and the functioning of pasture swards with a complex floristic composition are being studied in long-duration experiments, The data supply parameters and the means of evaluation for setting-up a mechanical model (GEMINI) that simulates the dynamics of the plant species and its consequences on the production and the quality of the herbage, and also on the workings of the soil. For the plants competing among themselves within the sward, GEMINI calculates the interception of light and of nitrogen, as well as the morphology of the above-ground parts and of the roots. The first modelling studies had borne on the simplified case of sown grass-clover associations. The present ambition of DISCOVER is to apply the model to swards with a complex floristic make-up, constituted by voluntary species, generally less well known. The effects of the number and of the type of species on the productivity of the pastures have been simulated, taking into account their plasticity of form and of function. Three examples of results are given. They concern : the role of the plasticity of leaf features in the response of grasses to nitrogen; the role of etiolation in the response of a dicotyledon to shade; and the role of the number of species and of functional groups in the productivity of the pasture. The applications of the model concern the role of bio-diversity in the ecological benefits of pastures with a complex floristic composition, and the simulation of the impacts of the climatic change.
La mise au point d'un modèle mécaniste permettant de simuler le fonctionnement de prairies à flore complexe est un projet ambitieux, permis par la synthèse de divers travaux de recherche en ...agronomie, zootechnie et écologie fonctionnelle. Les applications de ce type de modèle concernent la gestion des prairies, le rôle de la biodiversité pour les services écologiques des prairies et la simulation des impacts du changement climatique. Le projet DISCOVER étudie les relations entre la biodiversité et le fonctionnement de couverts prairiaux à flore complexe dans des expériences de longue durée, ce qui permet de paramétrer et d'évaluer un modèle mécaniste (GEMINI) lequel simule la dynamique des espèces végétales et ses conséquences pour la production végétale, la qualité de l'herbe et le fonctionnement du sol. Pour des plantes en compétition au sein du couvert, GEMINI calcule la capture de lumière et d'azote, ainsi que la morphologie des parties aériennes et des racines. Les effets du nombre et du type d'espèce pour la productivité de la prairie ont été simulés, en tenant compte de la plasticité de forme et de fonction des plantes. Des exemples de résultats sont donnés.
Within the framework of the 'DISCOVER' project (ANR Bio-diversity), the relationships between the bio-diversity and the functioning of pasture swards with a complex floristic composition are being studied in long-duration experiments, The data supply parameters and the means of evaluation for setting-up a mechanical model (GEMINI) that simulates the dynamics of the plant species and its consequences on the production and the quality of the herbage, and also on the workings of the soil. For the plants competing among themselves within the sward, GEMINI calculates the interception of light and of nitrogen, as well as the morphology of the above-ground parts and of the roots. The first modelling studies had borne on the simplified case of sown grass-clover associations. The present ambition of DISCOVER is to apply the model to swards with a complex floristic make-up, constituted by voluntary species, generally less well known. The effects of the number and of the type of species on the productivity of the pastures have been simulated, taking into account their plasticity of form and of function. Three examples of results are given. They concern : the role of the plasticity of leaf features in the response of grasses to nitrogen; the role of etiolation in the response of a dicotyledon to shade; and the role of the number of species and of functional groups in the productivity of the pasture. The applications of the model concern the role of bio-diversity in the ecological benefits of pastures with a complex floristic composition, and the simulation of the impacts of the climatic change.
Deterministic niche-based processes have been proposed to explain species relative abundance within communities but lead to different predictions: habitat filtering (HF) predicts dominant species to ...exhibit similar traits while niche differentiation (ND) requires that species have dissimilar traits to coexist. Using a multiple trait-based approach, we evaluated the relative roles of HF and ND in determining species abundances in productive grasslands. Four dimensions of the functional niche of 12 co-occurring grass species were identified using 28 plant functional traits. Using this description of the species niche, we investigated patterns of functional similarity and dissimilarity and linked them to abundance in randomly assembled six-species communities subjected to fertilization/disturbance treatments. Our results suggest that HF and ND jointly determined species abundance by acting on contrasting niche dimensions. The effect of HF decreased relative to ND with increasing disturbance and decreasing fertilization. Dominant species exhibited similar traits in communities whereas dissimilarity favored the coexistence of rare species with dominants by decreasing interspecific competition. This stabilizing effect on diversity was suggested by a negative relationship between species over-yielding and relative abundance. We discuss the importance of considering independent dimensions of functional niche to better understand species abundance and coexistence within communities.
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The authors describe a case of mucolipidosis I, the 9th reported in the world literature. The diagnosis was suspected in a 5 year old boy, from the appearance of hurler-like facial features. Lumbar ...kyphosis, dysostosis multiplex, cherry-red macular spot and foam cells in the bone marrow and it was confirmed by the characteristic oligosacchariduria (on thin layer chromatography) and excess sialic acid in cultured fibroblasts which also showed profoundly diminished activity of alpha D Neuraminidase (on two substrates - N-acetyl-Neuramin Lactose and 4 Methyl umbelliferyl N-acetyl-Neuraminide). The parents had intermediate enzyme activities, suggesting heterozygotism. After a review of the literature, the authors attempt to define the place of mucolipidosis I in the sialidoses.
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