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ANÁLISE ESPACIAL DOS PRINCIPAIS DETERMINANTES DA RENDA PER CAPITA DOS MUNICÍPIOS BRASILEIROS AgEcon
Lazzarotto, Joelsio Jose; Lima, Joao Eustaquio de.
Como no Brasil existem grandes heterogeneidades com relação à renda per capita, buscou-se estudar importantes aspectos determinantes da formação dessa renda nos diversos municípios. Com base em dados de 5.425 municípios, foram empregadas técnicas de análise exploratória de dados espaciais e de estimação de modelos econométricos espaciais. Dentre os resultados obtidos, pode-se destacar três: 1) existem grandes disparidades municipais relacionadas com os rendimentos individuais; 2) a análise exploratória de dados espaciais indicou a existência de dependência espacial envolvendo a renda per capita média dos municípios; e 3) os modelos econométricos estimados evidenciaram que, variações relacionadas com escolaridade, nível de emprego, desempenho dos setores...
Tipo: Conference Paper or Presentation Palavras-chave: Dependência espacial; Heterogeneidade espacial; Clusters municipais; Spatial dependence; Spatial heterogeneity; Municipal clusters; Financial Economics.
Ano: 2008 URL: http://purl.umn.edu/103145
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Assessing the influence of neighborhood effects on the adoption of improved agricultural technologies in developing agriculture AgEcon
Langyintuo, Augustine S.; Mekuria, Mulugetta.
Researchers generally assume spatial homogeneity when assessing the factors that influence farmers to adopt improved agricultural technologies. However, the potential for spatial heterogeneity is high due to, for example, neighborhood effects such as farmers sharing information about new technology. Ignoring spatial heterogeneity can result in biased or inefficient regression estimates and make inferences based on t and F statistics misleading. Using data collected from 300 randomly selected farmers in three districts of Mozambique during the 2003/04 crop season, a spatial Tobit model was specified to estimate which factors determined the adoption of improved maize varieties, after an initial diagnostic test rejected the null hypothesis of spatial...
Tipo: Journal Article Palavras-chave: Spatial Tobit model; Spatial heterogeneity; Spatial autocorrelation; Neighborhood effects; Maize farmers; Mozambique; Research and Development/Tech Change/Emerging Technologies.
Ano: 2008 URL: http://purl.umn.edu/56960
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Changes in the taxonomic structure of periphytic algae on a free-floating macrophyte (Utricularia foliosa L.) in relation to macrophyte richness over seasons Acta Botanica
Santos,Thiago Rodrigues dos; Ferragut,Carla.
ABSTRACT Periphyton has a strong relationship with aquatic macrophytes, which are key components of spatial heterogeneity in the littoral zone. We evaluated the relationship between the community structure of periphytic algae on Utricularia foliosa and macrophyte richness and coverage and limnological variables in a shallow reservoir. Water sampling for physical, chemical and biological analyses was performed at sites with contrasting macrophyte coverage and richness in each of the four main seasons of the year. Periphytic algae were evaluated for density and species composition. High densities of diatoms and filamentous cyanobacteria in the periphyton were observed at sites with high macrophyte coverage and richness, while high abundances of flagellates...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Epiphytic algae; Limnological variables; Macrophyte structure; Spatial heterogeneity; Species composition.
Ano: 2018 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062018000400595
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Co-occurring morphologically distinct algae support a diverse associated fauna in the intertidal zone of Araçá Bay, Brazil Biota Neotropica
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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Distribution quantitative de la macrofaune benthique du peuplement des cailloutis dans le détroit du Pas de Calais (Manche orientale, France) ArchiMer
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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Impacts of Agricultural Practices and Policies on Potential Nitrate Water Pollution in the Midwest and Northern Plains of the United States AgEcon
Wu, JunJie; Lakshminarayan, P.G.; Babcock, Bruce A..
An empirical model is developed to estimate the effects of alternative farming practices on potential nitrogen runoff and leaching in 128,591 National Resources Inventory sites across the Midwest and the Northern Plains of the United States. This model integrates the effects of soils, climate, crops, and management practices on nitrogen loss. The model is applied to evaluation of two policy scenarios. The first scenario reduces N fertilizer application rates by 25 percent through the soil N test. The second replaces continuous cropping practices with crop rotations. The results show that policy effects vary widely across the study region. This analysis emphasizes the importance of conducting policy analysis on a disaggregated scale.
Tipo: Working or Discussion Paper Palavras-chave: Farming practices; Nitrogen runoff and leaching; Spatial heterogeneity; Disaggregated policy analysis; Environmental Economics and Policy.
Ano: 1996 URL: http://purl.umn.edu/18386
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Investigating distance effects on environmental values: a choice modelling approach AgEcon
Concu, Giovanni B..
Analysis of the relationship between distance and willingness to pay (WTP) is important for estimation and transfer of environmental benefits. Several contingent valuation (CV) studies have investigated this topic, but results are mixed. This paper describes a choice modelling (CM) application that estimates distance effects on parameters of three environmental attributes. Combinations of these attributes create different management policies for native vegetation. The CM study is based on a sampling procedure that provides a geographically balanced sample and statistical tests to choose the best specification of the distance–WTP relationship. Welfare analysis shows that disregarding distance causes under-estimation of individual and aggregated benefits and...
Tipo: Journal Article Palavras-chave: Choice modelling; Geographical distance; Spatial heterogeneity; Stratified sample; Environmental Economics and Policy; Resource /Energy Economics and Policy.
Ano: 2007 URL: http://purl.umn.edu/118326
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Long-term Trend in Pre-grazing Horizontal Distribution of Herbage Mass in Bahiagrass Pasture (Paspalum notatum Flügge) JARTS
Maćešić, Dubravko; Hirata, Masahiko.
Grazing by cattle plays a main role in development of spatial heterogeneity in pasture and through it, as well, in stability of particular grazing system. In this study the first five years (1995-1999) of a long-term trial in pre-grazing distribution of herbage mass in bahiagrass pasture, utilised under the same repeated grazing management are shown. Herbage mass was non-destructively estimated with an electronic capacitance probe at 182, 50 by 50 cm locations along 2 permanent line transects. The changes in pre-grazing horizontal distribution of herbage mass during five grazing seasons were measured always on the same position on two transects just before the beginning of each grazing period (27 occasions). The pre-grazing herbage mass shows spatially...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Agronomy and Crop Science bahiagrass; Paspalum notatum; Grazing; Herbage mass; Spatial heterogeneity.
Ano: 2004 URL: http://www.jarts.info/index.php/jarts/article/view/49
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Modelling the spatial heterogeneity of ecological processes in an intertidal estuarine bay: dynamic interactions between bivalves and phytoplankton ArchiMer
Grangere, Karine; Lefebvre, Sebastien; Bacher, Cedric; Cugier, Philippe; Menesguen, Alain.
Spatial patterns in ecological communities result from a combination of physical and biological factors. In an estuarine intertidal bay, spatial differences have been found in the structure of phytoplanktonic communities and in the biological performance of cultivated oysters. It has been hypothesised that trophic heterogeneity exists, although the mechanisms controlling it remain undefined. Spatial and temporal interactions in the structure of phytoplanktonic biomass and in the biological performance of cultivated oysters were highlighted in this estuarine intertidal bay using a 2-dimensional hydrodynamic model coupled to a nutrient-phytoplankton-zooplankton bivalve food web model. The coupled models allowed a reproduction in space and time of variations...
Tipo: Text Palavras-chave: Spatial heterogeneity; Hydrodynamics; Ecosystem model; Food supply; Bivalves; Dynamic energy budget model; Physiological status; Baie des Veys.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00017/12854/9819.pdf
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Seed predation in a Mediterranean pasture: can ants modify the floristic composition of soil seed banks? RChHN
ESPIGARES,TÍSCAR; LÓPEZ-PINTOR,ANTONIO.
Ants may play an important role on vegetation dynamics, especially in arid and semiarid environments, where they can consume a high proportion of the produced seeds. Although some works have analysed the influence of seed predation by ants on the density of vegetation in Mediterranean pastures, there are no studies on the influence of ant activity upon the floristic composition of the vegetation and the soil seed banks in this kind of ecosystem. We have studied the effect of ant exclusion on the floristic composition of the vegetation and the soil seed bank in a Mediterranean pasture of central Spain. We sampled the floristic composition of the pasture during 2002 and 2003 springs and also we collected soil seed bank samples in autumn 2002. Floristic...
Tipo: Journal article Palavras-chave: Annual pasture; Ant exclusion; Predation; Soil seed bank; Spatial heterogeneity.
Ano: 2005 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2005000400002
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Spatial and temporal variation in the canopy cover in a tropical semi-deciduous forest BABT
Bianchini,Edmilson; Pimenta,José A.; Santos,Flavio A. M. dos.
This study was developed in the Mata dos Godoy State Park (23° 27’S, 51° 15’W) South Brazil which present great environmental heterogeneity when its north portion (ridge) is compared with the southern portion (valley), where there are some flooded areas. The forest formation is classified as tropical semi-deciduous forest. Spatial and temporal variations in the degree of the canopy cover were compared at flooded and unflooded sites. The measures were taken seasonally in 100m² plots using a spherical densiometer from spring 1995 to winter 1996. The flooded area was more open and lighter and had a greater spatial and temporal variation in the canopy cover than the unflooded areas. The greater heterogeneity in the flooded area could be due to structural...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Canopy; Flooding; Seasonality; Spatial heterogeneity; Tropical forest.
Ano: 2001 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132001000300008
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Spatial heterogeneity in the distribution of plants and benthic invertebrates in the lagoon of Orbetello (Italy) ArchiMer
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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Spatial heterogeneity of the Tucuruí Reservoir (State of Pará, Amazonia, Brazil) and the distribution of zooplanktonic species BJB
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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State-space analysis of soil data: an approach based on space-varying regression models Scientia Agricola
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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Toward a Normative Theory of Crop Yield Skewness AgEcon
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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Two Dimensions of the Spatial Distribution of Housing: Dependency and Heterogeneity across Tennessee’s Six Metropolitan Statistical Areas AgEcon
Cho, Seong-Hoon; Clark, Christopher D.; Park, William M..
A two-stage multinomial logit selection model is used to model the relationship between demographic characteristics and housing density across Tennessee’s six metropolitan statistical areas. The study finds that there is both spatial correlation and heterogeneity in the most densely populated area, has the least amount of spatial correlation among housing density at the neighborhood level, while Johnson City, which has the lowest overall housing density, has the highest degree of spatial correlation.
Tipo: Journal Article Palavras-chave: Community; Housing density; Spatial dependency; Spatial heterogeneity; Community/Rural/Urban Development; C31; R21.
Ano: 2006 URL: http://purl.umn.edu/43763
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What is the importance of open habitat in a predominantly closed forest area to the dung beetle (Coleoptera, Scarabaeinae) assemblage? Rev. Bras. entomol.
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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