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| Registros recuperados: 17 | |
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| De Biasi, Am; Benedetti-cecchi, L; Pacciardi, L; Maggi, E; Vaselli, S; Bertocci, I. |
| Many studies in marine coastal lagoons have focused on the marine-to-terrestrial gradient as a main source of variation for the structure of assemblages. In this paper, the magnitude of differences among locations arranged along the marine-to-terrestrial gradient of the western lagoon of Orbetello (Grosseto, Italy) was contrasted with the amount of spatial variability occurring among sets of locations that were not positioned along this axis. We propose that if the most important processes influencing assemblages were those associated with the external-internal gradient of the lagoon, as usually supposed, then assemblages should differ more among these locations than among any other locations. To test the above proposition, four locations arranged along... |
| Tipo: Text |
Palavras-chave: Hétérogénéité spatiale; Phyto- et zoo-benthos; Lagune côtière; Méditerranée occidentale; Spatial heterogeneity; Phytozoobenthos; Coastal lagoon; Western Mediterranean. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00322/43283/43018.pdf |
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| Migne, A; Davoult, D. |
| Because of strong tidal currents, the bottom of the Dover Strait consists of coarse sediment which is colonized by a pebble community. A quantitative study, based on 0.1 m(2) quadrat samples taken by divers, was conducted on this community to establish the richness of benthic macrofauna (in terms of biomass and diversity) and to provide conclusive data on global community structure (spatial and temporal heterogeneity, trophic structure). Eight samples were taken between June 1992 and June 1993, eight replicates being taken on each sampling visit. One hundred and one species were identified, in 10 zoological groups, and a mean biomass of 281 g.m(-2) (ash free dry weight) was calculated. The Shannon diversity index was low (H' = 1.24) because of the strong... |
| Tipo: Text |
Palavras-chave: Macrobenthos; Biomass; Trophic structure; Diversity; Spatial heterogeneity. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20409/18076.pdf |
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| De Montaudouin, X.; Lanceleur, L.. |
| We studied the spatial heterogeneity of infection of the marine bivalve Cerastoderma edule (cockle) by trematode parasites at 5 different scales in Banc d'Arguin, France. At the km-scale, the communities of trematodes differed among stations in terms of species composition and specific abundance. Infection heterogeneity was likely due to the occurrence of the definitive host and the conditions of transmission (water parameters). At the 100 m scale, trematode species richness was similar among stations, but specific trematode abundances differed. The most significant variable in terms of explaining trematode infection heterogeneity was the presence of the first intermediate host. At the 10 m scale, the distance at which parasite abundance diminished varied... |
| Tipo: Text |
Palavras-chave: Spatial heterogeneity; Aggregation pattern; Parasitism; Cerastoderma edule; Sampling scale. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00375/48647/49047.pdf |
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| Hennessy, David A.. |
| While the preponderance of empirical studies point to negative crop yield skewness in a wide variety of contexts, the literature provides few clear insights on why this is so. The purpose of this paper is to make three points on the matter. We show formally that statistical laws on aggregates do not suggest a normal yield distribution. We explain that whenever the weather-conditioned mean yield has diminishing marginal product, then there is a disposition toward negative skewness in aggregate yields. This is because a high marginal product in bad weather states stretches out the left tail of the yield distribution relative to that of the weather distribution. Turning to disaggregated yields, we decompose unconditional skewness into weather-conditioned... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Conditional distribution; Crop insurance; Negative skewness; Spatial heterogeneity; Statistical laws.. |
| Ano: 2008 |
URL: http://purl.umn.edu/37548 |
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| Costa,Fábio C.; Pessoa,Karen K. T.; Liberal,Carolina N.; Filgueiras,Bruno K. C.; Salomão,Renato P.; Iannuzzi,Luciana. |
| What is the importance of open habitat in a predominantly closed forest to the dung beetle assemblage? The Atlantic Forest in Brazil is one of the most highly disturbed ecosystems and is mainly represented by fragmented areas. However, in places where human disturbances have ceased, certain areas are showing a natural regeneration pattern. The aim of the present study was to determine how the dung beetle assemblage responds to distinct habitat structures in a fragment of Atlantic Forest. For such, open and closed forest areas were sampled in a fragment of the Atlantic Forest in the northeastern region of Brazil. Pitfall traps baited with excrement and carrion were used to collect the beetles. A total of 7,267 individuals belonging to 35 species were... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: CIMNC; Distribution patterns; Insecta; Spatial heterogeneity. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0085-56262013000300012 |
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| Timm,Luís Carlos; Barbosa,Emanuel Pimentel; Souza,Manoel Dornelas de; Dynia,José Flávio; Reichardt,Klaus. |
| The assessment of the relationship among soil properties (such as total nitrogen and organic carbon) taken along lines called transects is a subject of great interest in agricultural experimentation. This question has been usually approached through standard state-space methods by some authors in the soil science literature. Important limitations of the mentioned procedures used in practice are pointed out and discussed in this paper, specially those related to the model parameters, meaning and practical interpretation. In the standard state-space approach, based on an autoregressive structure, it does not present any parameters that express the variables relationship at the same point in space, but only at lagged points. Also, its model parameters (in the... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Dynamic regression; Soil properties; Spatial heterogeneity; Kalman filter. |
| Ano: 2003 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162003000200023 |
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| Vieira,Edson A.; Filgueiras,Heloísa Romeu; Bueno,Marília; Leite,Fosca Pedini Pereira; Dias,Gustavo Muniz. |
| Abstract Species diversity is regulated by historical, neutral and niche processes, with species tolerance, dispersal and productivity guiding diversity at larger scales, while habitat heterogeneity and biotic interactions acts in smaller scales. In rocky shores, several organisms provide secondary substrates for mobile fauna, with macroalgae being the most abundant and diverse ones. The patchiness promoted by different macroalgae hosts enhances small-scale heterogeneity and may increase and maintain the diversity of the mobile organisms, since there is a close relationship between the associated fauna and its hosts. In this study we selected three morphologically different macroalgae that coexist in the same rocky shore height in the Araçá Bay, an area... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Rocky shore; Phytal; Peracarids; Structural complexity; Spatial heterogeneity. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032018000100207 |
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| ESPÍNDOLA,E. L. G.; MATSUMURA-TUNDISI,T.; RIETZLER,A. C.; TUNDISI,J. G.. |
| With the purpose of analyzing the horizontal distribution of the zooplankton community of the Tucuruí Reservoir in the State of Pará, Brazil, collections were made at 16 stations during August 1988. The stations cover the regions called Caraipé (C), Araçagi (B) and Ararão (A), and represent the different compartments of this ecosystem in regard to the morphometry and the presence or absence of "flooded forest". Our findings showed the existence of three compartments with different limnological characteristics determined as a function of the system's morphometry, a factor that may have influenced the horizontal circulation of the reservoir's water and, consequently, led to physical, chemical and biological differences at each of the sampled stations. All... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Zooplankton; Horizontal distribution; Spatial heterogeneity; Reservoirs. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0034-71082000000200001 |
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| Registros recuperados: 17 | |
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