Consulta: subjectFacets:"Shannon index"
Registros recuperados: 6
Data/hora: 10/06/2024 09:06:26

A methodological framework to predict the individual and population‐level distributions from tracking data
Provedor de dados: 5
Autores: Chambault, Philippine; Hattab, Tarek; Mouquet, Pascal; Bajjouk, Touria; Jean, Claire; Ballorain, Katia; Ciccione, Stéphane; Dalleau, Mayeul; Bourjea, Jerome.
Despite the large number of species distribution modelling (SDM) applications driven by tracking data, individual information is most of the time neglected and traditional SDM approaches commonly focus on predicting the potential distribution at the species or population‐level. By running classical SDMs (population approach) with mixed models including a random factor to account for the variability attributable to individual (individual approach), we propose an innovative five‐steps framework to predict the potential and individual‐level distributions of mobile species using GPS data collected from green turtles. Pseudo‐absences were randomly generated following an environmentally‐stratified procedure. A negative exponential dispersal kernel was...
Tipo: Text
Palavras-chave: GPS tracking; Green turtles; Indian Ocean; Pseudo-absences; Shannon index; Spatial modelling.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00682/79412/81963.pdf

Species richness and diversity in shrub savanna using ordinary kriging
Provedor de dados: 86
Autores: Batista,Anderson Pedro Bernardina; Mello,José Márcio de; Raimundo,Marcel Régis; Scolforo,Henrique Ferraço; Reis,Aliny Aparecida dos; Scolforo,José Roberto Soares.
Abstract: The objective of this work was to analyze the spatial distribution and the behavior of species richness and diversity in a shrub savanna fragment, in 2003 and 2014, using ordinary kriging, in the state of Minas Gerais, Brazil. In both evaluation years, the measurements were performed in a fragment with 236.85 hectares, in which individual trees were measured and identified across 40 plots (1,000 m2). Species richness was determined by the total number of species in each plot, and diversity by the Shannon diversity index. For the variogram study, spatial models were fitted and selected. Then, ordinary kriging was applied and the spatial distribution of the assessed variables was described. A strong spatial dependence was observed between species...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Geostatistics; Shannon index; Variogram.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2016000800958

BANK OF WEED SEEDS IN AGROSYSTEMS IN THE BRAZILIAN CERRADO
Provedor de dados: 87
Autores: CARDOSO,I.S.; SOARES,M.P.; ARAÚJO,V.T.; CABRAL,P.H.R.; JAKELAITIS,A.; MADALÃO,J.C.
ABSTRACT The seed bank is the reserve of viable seeds found in the soil and is related to diversity and abundance of species that make up the weed populations. This study aimed to determine the seed bank in four distinct environments (grazing area, area of vegetables, annual crop area and perennial crop area) in two seasons (rainy and dry season). To determine the seed bank, each environment was divided into four sub-areas of 0.2 hectares, considering that each area was a repetition, totaling 16 experimental units. Samples of 0.8 kg were taken from each area, and each sample was distributed on a plastic tray and allowed to germinate in a greenhouse. The density of the individuals was determined by observing the number of emerging seedlings in the trays,...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Rainy season; Dry season; Shannon index; Relative importance; Diversity.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582016000300443

Opportunity Costs of Providing Crop Diversity in Organic and Conventional Farming: Would Targeted Environmental Policies Make Economic Sense?
Provedor de dados: 31
Autores: Sipilainen,   Timo; Huhtala,   Anni.
Targeted environmental policies for farmlands may improve the cost-efficiency of conservation programs if one can identify the farms that produce public goods, or environmental outputs, with the least cost. We derive shadow values of producing crop diversity on conventional and organic crop farms to examine their opportunity costs of conservation. Non-parametric distance functions are estimated by applying data envelopment analysis to a sample of Finnish crop farms for the period 1994 – 2002. Our results show that there is variation in the shadow values between farms and the technologies adopted. The extent of cost heterogeneity and farms’ potential for specialization in the production of environmental outputs determine whether voluntary programs such as...
Tipo: Conference Paper or Presentation
Palavras-chave: Biodiversity; Shannon index; DEA; Distance functions; Shadow values; Crop Production/Industries; Environmental Economics and Policy; C21; D24; H41; Q12; Q24.
Ano: 2011
URL: http://purl.umn.edu/114527

EFFICIENCY IN AGRICULTURAL PRODUCTION OF BIODIVERSITY: ORGANIC VS. CONVENTIONAL PRACTICES
Provedor de dados: 31
Autores: Sipilainen,   Timo; Marklund,   Per-Olov; Huhtala,   Anni.
Promotion of environmental sustainable farming practices is an important policy goal for the whole agricultural sector. However, when the efficiency of production is measured in practice, enhancement of environmental quality such as biodiversity and other environmental amenities does not seem to be recognized as a positive output produced by agriculture. Here, we include crop diversity index as an indicator of environmental output in a comparison of efficiency of conventional and organic crop farms. Non-parametric technical efficiency scores are estimated applying data envelopment analysis on a sample of Finnish crop farms for 1994 – 2002. The results show that in a pooled data set conventional crop farms are more technically efficient than organic farms...
Tipo: Conference Paper or Presentation
Palavras-chave: Crop diversity; Shannon index; DDEA; Technical efficiency; Environmental Economics and Policy; Farm Management; Research Methods/ Statistical Methods.
Ano: 2008
URL: http://purl.umn.edu/6478

Composition, structure and diversity of a mesquite in Pesquería (Northeastern Mexico)
Provedor de dados: 97
Autores: Alanís-Rodríguez,Eduardo; Molina-Guerra,Víctor M.; Jiménez-Pérez,Javier; Rubio-Camacho,Ernesto A.; Mora-Olivo,Arturo; Collantes-Chávez-Costa,Alejandro; Marroquín-Castillo,Jonathan J.
Abstract  Background: Although the mesquite (mesquital or mezquital in Spanish) is one of the representative ecosystems of the landscapes in the north of Mexico, it is also one of the least studied. This study evaluated the structure (horizontal and vertical) and diversity of a plant community of mesquite in Northeastern Mexico. Three plots of 1,600 m2 each were established. All trees and shrubs with a basal diameter (d0.10) &amp;#8805; 0.5 cm were recorded, and total height (h) and crown diameter (dcrown) were measured.  Results: There were 8 families, 12 genera and 14 species. The genus presenting the most species was Acacia (three species). The most representative family was Fabaceae with seven species. The evaluated community presents a density of 375...
Tipo: Journal article
Palavras-chave: Importance value index; Margalef diversity index; Mesquital; Plant community; Prosopis glandulosa; Shannon index.
Ano: 2017
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2017000100201