SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Les pêcheries mixtes de langoustine et de merlu du golfe de Gascogne. Description, préparation à une modélisation et à une simulation des procédures de gestion

Bacher, Cedric; Baud, Jean-pierre; Bodoy, Alain; Deslous-paoli, Jean-marc; Dreno, Jean-paul; Heral, Maurice; Maurer, Daniele; Prou, Jean.

An assessment of the reared stocks of the Pacific oyster (Crassostrea gigas ) has been recently conducted on the major French areas of molluscs culture. The methodology proposed included both estimates of densities obtained by subsampling in the field, and aerial photographs which covered the cultivated, intertidal area. The size and the number of samples were designed to reach a precision of 10% on the final assessment in each area. The field work consisted in weighing and counting the oyster in unit areas of 0.5 m2 for the bottom culture or in trays or bags, for the off bottom technique. These results give a better knowledge of the technique evolution and of the general structures in the cultivated areas.

Tipo: Text

Palavras-chave: Modeling; Estimation; Stocks; Crassostrea gigas; Oysters.

Ano: 1986

URL: http://archimer.ifremer.fr/doc/1986/acte-2864.pdf

Méthodes pour la typologie des flottilles de pêche : bilan et ouvertures

Charuau, Anatole; Ifremer.

1 - Study's goals review The management of Norway Lobster and Hake fisheries can be considered as the most important issue in the Gascogne gulf. Calculation methods used to evaluate prediction variations under various efforts and mesh constraints all pinpoint to the crucial role narrow mesh fishing plays in Hakes' Northern stock status. The involvement of Gascogne gulf Norway Lobster fisheries regarding Hakes over exploitation seems over dimensioned when comparing the size of both of these stocks. Hake stocks spread from Northern Great Britain to Northern Spain, while Norway Lobster stocks are located in the Gascogne gulf's mud flats. The biological solution is well known and consists in globally increasing mesh nets to 80mm which would bring up Hakes...

Tipo: Text

Palavras-chave: Procedures of management; Modeling; Bay of Biscay; Mixed fishery; Lobster; Hake.

Ano: 1987

URL: http://archimer.ifremer.fr/doc/1987/rapport-1763.pdf

Challenges in adaptive management of riparian and coastal ecosystems

Rochet, Marie-joelle; Ferraris, Jocelyne; Biseau, Alain; Sabatier, R.

Introduction: Twenty reports or articles concerning fishing fleet typology work have been analysed. All of them come from IFREMER, except for two articles; one was published by Danish researchers and the other by Americans. Our purpose here is to review and assess this work on a methodological standpoint in order to identify if the objectives announced and methods used are adequately in line.

Tipo: Text

Palavras-chave: Capture; Statistics; Modeling; Typology; Fishing; Fleet.

Ano: 1994

URL: http://archimer.ifremer.fr/doc/1994/rapport-1746.pdf

Walters, Carl; University of British Columbia; c.walters@fisheries.ubc.ca.

Many case studies in adaptive-management planning for riparian ecosystems have failed to produce useful models for policy comparison or good experimental management plans for resolving key uncertainties. Modeling efforts have been plagued by difficulties in representation of cross-scale effects (from rapid hydrologic change to long-term ecological response), lack of data on key processes that are difficult to study, and confounding of factor effects in validation data. Experimental policies have been seen as too costly or risky, particularly in relation to monitoring costs and risk to sensitive species. Research and management stakeholders have shown deplorable self-interest, seeing adaptive-policy development as a threat to existing research programs and...

Tipo: Peer-Reviewed Reports

Palavras-chave: Adaptive management; Coastal ecosystems; Ecosystem management; Fisheries; Institutional barriers; Management experiments; Modeling; Riparian ecosystems; Simulation.

Ano: 1997

Sugarcane leaf area index modeling under different soil water conditions

Scientia Agricola

Teruel,D.A.; Barbieri,V.; Ferraro Jr.,L.A..

The knowledge of the Leaf Area Index (LAI) variation during the whole crop cycle is essential to the modeling of the plant growth and development and, consequently, of the crop yield. Sugarcane LAI evolution models were developed for different crop cycles, by adjusting observed LAI values and growing degree-days summation data on a power-exponential function. The resultant equations simulate adequately the LAI behavior during the entire crop cycle. The effect of different water stress levels was calculated in different growth periods, upon the LAI growth The LAI growth deficit was correlated with the ratio between actual evapotranspiration and máximum evapotranspiration, and a constant named kuu was obtained hi each situation. It was noticed that the kLAI...

Vadose zone measurement and modeling

Palavras-chave: Leaf Area Index; Sugarcane; Growing degree-days; Water stress; Modeling.

Ano: 1997

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90161997000300008

Scientia Agricola

Hopmans,J. W.; Clausnitzer,V.; Kosugi,K.I.; Nielsen,D.R.; Somma,F..

The following treatise is a summary of some of the ongoing research activities in the soil physics program at the University of California in Davis. Each of the four listed areas win be presented at the Workshop on special topics on soil physics and crop modeling in Piracicaba at the University of Sao Paulo. We limited ourselves to a general overview of each area, but will present a more thorough discussion with examples at the Workshop.

Determination of a long-term optimal irrigation strategy for dry beans in Parana State, Brazil

Palavras-chave: Unsaturated zone; Water flow; Transport processes; Modeling.

Ano: 1997

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90161997000300004

Scientia Agricola

Faria,R.T. de; Folegatti,M.V.; Frizzone,J.A.; Saad,A.M..

The economical benefits of different irrigation strategies were assessed by long term simulation (20 years) for dry beans in Paraná, Brazil. The model BEANGRO was used to simulate crop yield and irrigation requirements assuming eight levels of irrigation threshold (20 to 90% of the remaining soil available water in steps of 10%), in addition to a level considering no irrigation. Net return was the objective function to select the optimum irrigation management strategy, assuming fixed and stochastic distributions of historical product price. The results showed that yield was significantly increased by irrigation despite a high variability for all the simulation strategies, due to variations on growth conditions over the years. Although the net return was...

Adaptive Analysis of Locally Complex Systems in a Globally Complex World

Palavras-chave: Irrigation; Modeling; Economical analysis.

Ano: 1997

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90161997000300018

Lynam, Timothy; Tropical Resource Ecology Program, University of Zimbabwe; tlynam@science.uz.ac.zw.

Zambezi Valley agro-ecosystems are environmentally, economically, and institutionally variable. This variability means that it is not possible to measure everything necessary to develop a predictive understanding of them. In particular, because people and their environments are constantly changing, what was measured yesterday may change by tomorrow. Here, I describe elements of the approach that I have developed to address this problem. Called DAAWN, for Detail as and When Needed, the approach advocates an iterative and multiscaled methodology in which we first capture as broad an understanding of the system as possible and then use awareness developed at this scale to identify where to focus subsequent, more detailed, investigations. Because we cannot...

Tipo: Peer-Reviewed Reports

Palavras-chave: Comples adaptive systems; Household and resource economics; Livelihood strategies; Modeling; Multi-agent simulation models; Natural resource use; Participatory systems analysis; Southern Africa; Spidergrams.

Ano: 1999

On Nature, Models, and Simplicity

Baumann, Michael; University of British Columbia and ananature.com Scientific Services; baumann@interchange.ubc.ca.

Tipo: Peer-Reviewed Reports

Palavras-chave: Complexity; Epistemology; Modeling; Simplicity.

Ano: 2000

Global-Scale Patterns of Forest Fragmentation

Riitters, Kurt; U.S. Forest Service; kriitters@fs.fed.us; Wickham, James D; U.S. Environmental Protection Agency, National Exposure Research Laboratory; wickham.james@epa.gov; O'Neill, Robert; ; eoneill@attglobal.net; Jones, K. Bruce; U.S. Environmental Protection Agency, National Exposure Research Laboratory; jones.bruce@epa.gov; Smith, Elizabeth; U.S. Environmental Protection Agency, National Exposure Research Laboratory; smith.betsy@epa.gov.

We report an analysis of forest fragmentation based on 1-km resolution land-cover maps for the globe. Measurements in analysis windows from 81 km 2 (9 x 9 pixels, “small” scale) to 59,049 km 2 (243 x 243 pixels, “large” scale) were used to characterize the fragmentation around each forested pixel. We identified six categories of fragmentation (interior, perforated, edge, transitional, patch, and undetermined) from the amount of forest and its occurrence as adjacent forest pixels. Interior forest exists only at relatively small scales; at larger scales, forests are dominated by edge and patch conditions. At the smallest scale, there were significant differences in fragmentation among continents; within continents,...

Tipo: Peer-Reviewed Reports

Palavras-chave: Biogeography; Edge effect; Forest fragmentation; Geographic information systems; Global patterns; Land-cover map; Landscape ecology; Modeling; Perforated forest; Remote sensing; Satellite imagery; Spatial pattern.

Ano: 2000

Simulation of a coastal jet retention process using a barotropic model

Penven, Pierrick; Roy, Claude; Colin De Verdiere, Alain; Largier, John.

In the southern Benguela, sardine and anchovy spawn on the Western Agulhas Bank. Eggs and larvae are transported to the West coast nursery ground by a! coastal current. Once the larvae reach the West coast, retention within the favorable coastal domain is key to larvae survival and recruitment. The Cape Columbine-St Helena Bay area is the main nursery ground along the West Coast. In this area, the interaction between upwelling and topography results in the formation of an upwelling plume. The plume, and the associated circulation patterns, is thought to be the mechanism providing retention within the coastal domain. The dynamics of the plume are studied using a set of:numerical experiments. It is shown that an equatorward wind forcing produces a cyclonic...

Tipo: Text

Palavras-chave: Benguela; Effets de cap; Modélisation; Rétention; Recrutement; Benguela; Cape effects; Modeling; Retention; Recruitment.

Ano: 2000

URL: http://archimer.ifremer.fr/doc/00323/43385/42826.pdf

Evaluation of EPIC for Three Minnesota Cropping Systems

AgEcon

Chung, S.W.; Gassman, Philip W.; Huggins, David R.; Randall, G.W..

The Erosion Productivity Impact Calculator (EPIC) model was tested using four years of field data collected at a site near Lamberton, Minnesota, under three different crop rotations: continuous corn (Zea mays L.) or CC, soybean (Glycine max L.)-corn (SC), continuous alfalfa (Medicago sativa L.) or CA. The model was evaluated by comparing measured versus predicted subsurface drainage flow (tile flow), nitrate-nitrogen (NO3-N) loss in tile flow, residual NO3-N in the soil profile, crop N uptake, and yield. Initially, EPIC was run using standard Soil Conservation Service (SCS) runoff curve numbers (CN2) suggested for the soil type at the site. Two different SC runs were performed with a nitrogen fixation parameter denoted as parm(7) set at either 1.0 or 0.3,...

Tipo: Working or Discussion Paper

Palavras-chave: Modeling; Water quality; Crop rotation; Tile drainage; Nitrate leaching; Fertilizer; Crop Production/Industries.

Ano: 2000

URL: http://purl.umn.edu/18479

Modeling gallic acid production rate by empirical and statistical analysis

BABT

Kar,Bratati; Banerjee,Rintu; Bhattacharyya,Bimal Chandra.

For predicting the rate of enzymatic reaction empirical correlation based on the experimental results obtained under various operating conditions have been developed. Models represent both the activation as well as deactivation conditions of enzymatic hydrolysis and the results have been analyzed by analysis of variance (ANOVA). The tannase activity was found maximum at incubation time 5 min, reaction temperature 40ºC, pH 4.0, initial enzyme concentration 0.12 v/v, initial substrate concentration 0.42 mg/ml, ionic strength 0.2 M and under these optimal conditions, the maximum rate of gallic acid production was 33.49 mumoles/ml/min.

Assessing the Performance of Natural Resource Systems

Palavras-chave: Gallic acid; Modeling; Tannase; Caesalpinia digyna.

Ano: 2000

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132000000500010

Campbell, Bruce; Center for International Forestry Research (CIFOR); b.campbell@cgiar.org; Sayer, Jeffrey A; WWF (World Wildlife Fund); jsayer@wwfint.org; Frost, Peter; Institute of Environmental Studies; pfrost@compcentre.uz.ac.zw; Vermeulen, Sonja; International Institute for Environment and Development; sonja.vermeulen@iied.org; Cunningham, Tony; World Wildlife Fund/UNESCO/Kew People and Plants Initiative; peopleplants@bigpond.com; Prabhu, Ravi; CIFOR Regional Office; r.prabhu@cgiar.org.

Assessing the performance of management is central to natural resource management, in terms of improving the efficiency of interventions in an adaptive-learning cycle. This is not simple, given that such systems generally have multiple scales of interaction and response; high frequency of nonlinearity, uncertainty, and time lags; multiple stakeholders with contrasting objectives; and a high degree of context specificity. The importance of bounding the problem and preparing a conceptual model of the system is highlighted. We suggest that the capital assets approach to livelihoods may be an appropriate organizing principle for the selection of indicators of system performance. In this approach, five capital assets are recognized: physical, financial, social,...

Tipo: Peer-Reviewed Reports

Palavras-chave: Capital assets; Conceptual models; Decision support; Livelihoods; Modeling; Multivariate statistics; Natural resource systems; Performance; Zimbabwe.

Ano: 2001

Spéciation des contaminants métalliques en milieu estuarien : Intérêt de la modélisation et application au cadmium

Gonzalez, Jean-louis; Dange, Catherine; Thouvenin, Benedicte.

In estuarine environment, cadmium has a nonconservative behavior. It can be present under various species: dissolved (mineral and organic complexes), colloidal and particulate forms (adsorbed, precipitated), or integrated by various mechanisms in the organisms. This distribution is the result of processes (physical, chemical and biological) which are controlled by many factors (salinity, pH, Eh, nature and concentration of suspended matter, primary production). Geochemical modeling is a very useful approach to understand the dynamics of this type of contaminant, especially in the complex systems which are the estuaries. A speciation model was used to simulate the measurements taken (dissolved and particulate Cd) during various cruises carried out in the...

Tipo: Text

Palavras-chave: Cadmium; Estuary; Speciation; Modeling; Surface complexation; Cadmium; Estuaire; Spéciation; Modélisation; Complexation de surface.

Ano: 2001

URL: https://archimer.ifremer.fr/doc/00480/59120/61749.pdf

Modellierung von Betriebsentwicklung und Nachhaltigkeitszielen

AgEcon

Zeddies, Jurgen.

In his numerous textbooks WILHELM BRANDES has laid the foundation for theoretically appropriate modeling of farm firms, which has recently been expanded to modeling sustainability goals. The published research results belong to the fields of economic, ecological, and social sustainability. Standard method for the analysis of economic sustainability is the gross margin calculation, for the given purpose extended by associated opportunity costs and/or by appropriately adding further associable branch specific costs. At an on-farm-basis the system has been developed to a management information system under sustainability goals which has been further developed to the new forms of precision agriculture by incorporating yield and soil nutrient mapping,...

Tipo: Journal Article

Palavras-chave: Farm planning; Modeling; Sustainability goals; International competitiveness; Transform processes; Agro-environmental policy; Environmental Economics and Policy; Farm Management.

Ano: 2001

URL: http://purl.umn.edu/99003

Modelo de balanço de nitrogênio para a cana-de-açúcar fase II - construção de modelo software STELLA.

Infoteca-e

BERGAMASCO, A. F.; SILVA, F. C. da; RODRIGUES, L. H. A.; TRIVELIN, P. C. O..

A cultura da cana-de-açúcar vem sofrendo mudanças, de âmbitos tecnológicos e sociais, profundas nesta década, procurando se adaptar às demandas de produção com alta produtividade, competitividade e respeito ao meio ambiente. Apesar de o Brasil ser o maior produtor mundial de cana-de-açúcar, ainda pratica a queima da palha do canavial para facilitar a colheita, o que gera prejuízos econômicos, sociais e ambientais. Sem essa queima (Decreto n.° 42056 do Estado de SP), a cobertura do solo pela palhada irá provocar significativas mudanças no manejo da cultura e na dinâmica do nitrogênio. Dada a complexibilidade do ciclo de nitrogênio no solo, seus vários caminhos de transformação, e as variações climáticas, é difícil a determinação do melhor manejo do...

Tipo: Boletim de Pesquisa e Desenvolvimento (INFOTECA-E)

Palavras-chave: Cana-de-açucar; Adubação nitrogenda; Software ESTELLA; Modelagem matemática; Modeling; Sugar cane.; Modelo Matemático..

Ano: 2002

URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/8690

Bias in the paleoceanographic time series: Tests with a numerical model of U, C-org, and Al burial

Etude du comportement des éléments traces en milieu estuarien : approche expérimentale et modélisation : Application à l'étude de la spéciation de Cd, Co et Cs dans les estuaires majeurs français (Seine, Loire, Gironde, Rhône)

Donnadieu, Y; Lecroart, P; Anschutz, P; Bertrand, P.

We have constructed a nonsteady state numerical model of organic carbon, aluminum, and uranium burial to examine the dynamic response of sediments to variations on thousand years scale. The three components are defined by distinct behaviors in the sedimentary system. The aluminum is a conservative component, the organic carbon is a nonconservative component degraded in superficial sediment, and the uranium is a component affected by redox conditions. By introducing a simultaneous variation of incoming fluxes of C-org and Al, geochemical profiles of Al, Corg, and U clearly show separate distributions after burial. Each component record the synchronous variation of the incoming fluxes, but the position in the sedimentary pile of the recording differs from a...

Tipo: Text

Palavras-chave: Time lag; Sedimentary system; High-resolution record; Modeling; Bioturbation.

Ano: 2002

URL: https://archimer.ifremer.fr/doc/00223/33390/31872.pdf