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Author |
Lang, G.; Marcon, E.; Puech, F. |
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Title |
Distance-based measures of spatial concentration: introducing a relative density function |
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Journal Article |
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Year |
2020 |
Publication |
Annals of Regional Science |
Abbreviated Journal |
Ann. Reg. Sci. |
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64 |
Issue |
2 |
Pages |
243-265 |
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Agglomeration; Aggregation; Economic geography; Point patterns; Spatial concentration; accuracy assessment; econometrics; economic activity; economic geography; industrial agglomeration; industrial location; location decision; spatial analysis; spatial distribution |
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For more than a decade, distance-based methods have been widely employed and constantly improved in spatial economics. These methods are a very useful tool for accurately evaluating the spatial distribution of economic activity. We introduce a new distance-based statistical measure for evaluating the spatial concentration of industries. The m function is the first relative density function to be proposed in economics. This tool supplements the typology of distance-based methods recently drawn up by Marcon and Puech (J Econ Geogr 3(4):409–428, 2003). By considering several simulated and real examples, we show the advantages and the limits of the m function for detecting spatial structures in economics. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature. |
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RITM, Univ. Paris-Sud, Université Paris-Saclay and CREST, Sceaux, France |
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05701864 (Issn) |
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EcoFoG @ webmaster @ |
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976 |
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Author |
Urbina, I.; Grau, O.; Sardans, J.; Ninot, J.M.; Peñuelas, J. |
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Title |
Encroachment of shrubs into subalpine grasslands in the Pyrenees changes the plant-soil stoichiometry spectrum |
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Journal Article |
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Year |
2020 |
Publication |
Plant and Soil |
Abbreviated Journal |
Plant Soil |
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Volume |
448 |
Issue |
1-2 |
Pages |
37-53 |
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Keywords |
Nutrient stocks; Plant strategy; Plant-soil stoichiometry; Shrub encroachment; Subalpine grassland succession; aboveground biomass; biogeochemical cycle; carbon sequestration; ectomycorrhiza; fungus; grass; nitrogen; nutrient uptake; shrub; soil-vegetation interaction; stoichiometry; subalpine environment; succession; Europe; Pyrenees; Fungi |
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Aims: Shrub encroachment has been reported over a large proportion of the subalpine grasslands across Europe and is expected to have an important impact on the biogeochemical cycle of these ecosystems. We investigated the stoichiometric changes in the plant-soil system along the succession (e.g. increase in encroachment from unencroached grassland to mature shrubland) at two contrasting sites in the Pyrenees. Methods: We analyzed the chemical composition (C, N,15N, P, K, Ca, Mg and Fe) in the soil and in the aboveground plant compartments (leaves, leaf-litter and stems) of the main herbaceous species and shrubs at three contrasting stages of the succession: unencroached grassland, young shrubland and mature shrubland. Results: The plant-soil stoichiometry spectrum differed between the successional stages. Shrub encroachment generally increased the concentration of C and Ca and the C:N ratio and often reduced to concentrations of N, P and K in the leaves and leaf-litter, while several soil nutrient concentrations (N, P, K Ca and Mg) decreased. The stocks of C, N, P, Ca, and Mg in the total aboveground biomass increased with encroachment. Conclusions: Shrub encroachment favored the dominance of long-lived species with low concentrations of N and P in the plant-soil compartments, high C:nutrient ratios in the aboveground biomass and increase the uptake of N through ericoid or ectomycorrhizal fungi. We highlight the role of shrubs in the sequestration of C and nutrients through the allocation to the aboveground biomass. The changes in plant-soil elemental composition and stocks suggest a slowdown of the biogeochemical cycles in the subalpine mountain areas where shrub encroachment occurred. © 2020, Springer Nature Switzerland AG. |
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Biodiversity Research Institute (IRBio) and Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Catalonia, Spain |
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0032079x (Issn) |
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EcoFoG @ webmaster @ |
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983 |
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Garcia-Davila, C.; Aldana Gomero, D.; Renno, J.-F.; Diaz Soria, R.; Hidalgo Pizango, G.; Flores Llampazo, G.; Castro-Ruiz, D.; Mejia de Loayza, E.; Angulo Chavez, C.; Mader, M.; Tysklind, N.; Paredes-Villanueva, K.; del Castillo Torres, D.; Degen, B.; Honorio Coronado, E.N. |
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Title |
Molecular evidence for three genetic species of Dipteryx in the Peruvian Amazon |
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Journal Article |
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Year |
2020 |
Publication |
Genetica |
Abbreviated Journal |
Genetica |
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Volume |
148 |
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1 |
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1-11 |
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Keywords |
D. micrantha; Dipteryx charapilla; Genetic diversity; Microsatellites; Sequencing; Shihuahuaco; microsatellite DNA; plant DNA; allele; Dipteryx; DNA sequence; genetic variation; genetics; genotype; haplotype; Peru; phylogeny; plastid; river; species difference; Alleles; Dipteryx; DNA, Plant; Genetic Variation; Genotype; Haplotypes; Microsatellite Repeats; Peru; Phylogeny; Plastids; Rivers; Sequence Analysis, DNA; Species Specificity |
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There is a high international demand for timber from the genus Dipteryx, or “shihuahuaco” as it is known in Peru. Developing tools that allow the identification and discrimination of Dipteryx species is therefore important for supporting management of natural populations and to underpin legal trade of its timber. The objective of this study was the molecular characterization of Dipteryx species in the Peruvian Amazonia. Two plastid regions (cpDNA: trnH–psbA and matK) were sequenced and 11 microsatellite markers (nDNA) were genotyped for 32 individuals identified as Dipteryx charapilla, D. micrantha morphotype 1 and D. micrantha morphotype 2. Using the concatenated sequences of the plastid genes, we identified ten haplotypes that were not shared between the species or between the D. micrantha morphotypes. Haplotypic diversity was greater in D. micrantha morphotype 2 and D. charapilla than in D. micrantha morphotype 1, which presented only one haplotype with a wide distribution in Peru. The microsatellites allowed the discrimination of the same three clades and identified diagnostic alleles for each clade. These results allowed us to demonstrate that the two morphotypes of D. micrantha are different at both the plastid and nuclear markers, which supports the existence of three genetically distinct species in Peru. This study provides information for the genetic discrimination of Dipteryx species and emphasises the importance of conserving the genetic variability of this genus in the Peruvian Amazonia. © 2019, Springer Nature Switzerland AG. |
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Carrera de Ingeniería Foresta, Laboratorio de Dendrocronología, Facultad de Ciencias Agrícolas, Universidad Autónoma Gabriel René Moreno, Km 9 carretera al Norte, El Vallecito, Santa Cruz, Bolivia |
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Springer |
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00166707 (Issn) |
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EcoFoG @ webmaster @ |
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990 |
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Author |
Céréghino, R.; Corbara, B.; Leroy, C.; Carrias, J.-F. |
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Title |
Ecological determinants of community structure across the trophic levels of freshwater food webs: a test using bromeliad phytotelmata |
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Journal Article |
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Year |
2020 |
Publication |
Hydrobiologia |
Abbreviated Journal |
Hydrobiologia |
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Volume |
847 |
Issue |
2 |
Pages |
391-402 |
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Keywords |
Environmental filtering; Functional group; Neotropical; Niche; Trophic interactions; alga; assembly rule; bacterium; community structure; ecological modeling; environmental conditions; food web; freshwater ecosystem; functional group; Neotropic Ecozone; niche; protozoan; taxonomy; trophic interaction; trophic level; algae; Invertebrata; Protozoa |
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Understanding the relative importance of habitat and biotic drivers on community assembly across food web components is an important step towards predicting the consequences of environmental changes. Because documenting entire food webs is often impractical, this question has been only partially investigated. Here, we partitioned variation in species assemblages of the major components of tank bromeliad food webs (bacteria, algae, protozoans, detritivorous and predatory invertebrates) into habitat and biotic determinants and examined the influence of habitat variables and predator or prey abundance on all taxonomic assemblages. Ecological determinism of assemblage structure ranged from weak in bacteria (< 10% of the explained variance) to strong in predatory invertebrates (90%). Habitat features and canopy openness significantly influenced species assemblages; however, prey or predator density had far and away the most significant structuring effects. If biotic forces are at least as important as the abiotic forces while the importance of stochasticity declines towards upper trophic levels, then trophic levels could respond differently to natural or anthropogenic disturbance and to shifts in species distributions. The effects of such differential responses on food web reconfiguration, however, remain to be elucidated. © 2019, Springer Nature Switzerland AG. |
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UMR EcoFoG (AgroParisTech, CIRAD, CNRS, INRA, Université de Guyane, Université des Antilles), Kourou, 97310, France |
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Springer |
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00188158 (Issn) |
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EcoFoG @ webmaster @ |
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996 |
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Author |
Mahoui,Sihem ; Moulay, Mohamed Said ; Omrane, Abdennebi |
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Title |
Finite element approach to linear parabolic pointwise control problems of incomplete data |
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Journal Article |
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Year |
2020 |
Publication |
International Journal of Systems Science |
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51 |
Issue |
14 |
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2597-2609 |
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Optimal control problem ; low-regret control ; pointwise control ; finite element method ; a priori error estimates |
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In this paper we give a priori error estimates for finite element approximations of linear parabolicproblems with pointwise control and incomplete data. We discretise the optimal control problemby using piecewise linear and continuous finite elements for the space discretisation of the state,and we use the backward Euler scheme for time discretisation. We prove a priori error estimates forthe state, the adjoint-state as well as for the low-regret pointwise optimal control. |
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TAYLOR & FRANCIS LTD |
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EcoFoG @ webmaster @ |
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935 |
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Shepard, W.D.; Clavier, S.; Cerdan, A. |
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A generic key to the known larval elmidae (Insecta: Coleoptera) of French Guiana |
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Journal Article |
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2020 |
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Papeis Avulsos de Zoologia |
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Pap. Avulsos Zool. |
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60 |
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Special |
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e202060 |
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Keywords |
Biodiversity; Identification; Immatures; Neotropical; Survey |
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An identification key is provided for 21 larval types of Elmidae (riffle beetles) known to occur in French Guiana. Not all elmid genera known to occur in French Guiana are known in the larval stage. Nor are all the known larval types assigned to known elmid genera. © 2020, Universidade de Sao Paulo. All rights reserved. |
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CNRS, UMR EcoFog (AgroParisTech, CIRAD, INRA, Université des Antilles, Université de Guyane), Kourou Cedex, France |
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Universidade de Sao Paulo |
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00311049 (Issn) |
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EcoFoG @ webmaster @ |
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980 |
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Vleminckx, J.; Bauman, D.; Demanet, M.; Hardy, O.J.; Doucet, J.-L.; Drouet, T. |
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Past human disturbances and soil fertility both influence the distribution of light-demanding tree species in a Central African tropical forest |
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Journal Article |
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2020 |
Publication |
Journal of Vegetation Science |
Abbreviated Journal |
J. Veg. Sci. |
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31 |
Issue |
3 |
Pages |
440-453 |
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Keywords |
light-demanding species; moist tropical forests; past human disturbances; shade-bearer species; soil charcoal abundance; soil properties; tree community assemblages; wood-specific gravity; anthropogenic effect; forest canopy; forest ecosystem; shifting cultivation; soil fertility; soil property; tree; tropical forest; Cameroon |
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Questions: In vast areas of Central African forests, the upper canopy is presently dominated by light-demanding tree species. Here, we confront three hypotheses to explain this dominance: (a) these species have expanded their distribution because of widespread past slash-and-burn activities, as suggested by important charcoal amounts recorded in the soils of the region; (b) their abundance is rather explained by soil properties, as this guild establishes preferentially on favourable physico-chemical conditions for rapid growth; (c) soil properties have been substantially influenced by past human disturbances and those two effects cannot be disentangled. Location: Pallisco-CIFM logging concession, southeastern Cameroon (300,000 ha). Methods: We quantified soil charcoal abundance and measured ten soil variables at the basis of 60 target trees that belonged to a list of three long-living pioneer light-demanding (LLP) and four shade-bearer (SB) species. We identified all stems with a diameter at breast height (DBH) ≥ 20 cm within a distance of 15 m around each target tree. Species were characterised by their wood-specific gravity (WSG), which reflected their light requirement. Multiple regression models were used to quantify and test the relative effects of charcoal abundance and soil variables on the mean WSG of the 60 tree communities, as well as the abundance of three guilds: LLP, SB, and non-pioneer light demanders (NPLD). Results: The mean WSG was the only response variable significantly explained by soil variables and charcoal abundance combined. It was significantly negatively associated with soil calcium and Mg content and with charcoal abundance, with soil and charcoal influencing the mean WSG independently. Conclusion: Our study provides evidence that past human disturbances and soil fertility have independently promoted the establishment of light-demanding species in western Central African forests, thereby shedding light on tree community assembly rules in these ecosystems which remain considerably understudied compared to the tropical forests of other continents. © 2020 International Association for Vegetation Science |
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Forest is life, TERRA Teaching and Research Centre, Université de Liège – Gembloux Agro-Bio Tech, Gembloux, Belgium |
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Wiley-Blackwell |
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11009233 (Issn) |
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EcoFoG @ webmaster @ |
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970 |
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