Quantifying the trends expected in developing ecosystems

Mageau, Michael T.; Costanza, Robert; Ulanowicz, Robert E.

doi:10.1016/s0304-3800(98)00092-1

Cited by 71 publications

(28 citation statements)

References 30 publications

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“…The diversity in network connections is not necessarily used to its full extent. Mageau et al (1998) defined the AMI as: ''… a measure of the information we have regarding the exchange of material within the system. If material from any compartment had the equal chance of flowing into any other compartment, then we have no information regarding the flow in the network.…”

Section: Indicators To Assess Diversitymentioning

confidence: 99%

Analysing integration and diversity in agro-ecosystems by using indicators of network analysis

Rufino

Hengsdijk

Verhagen

2009

Nutr Cycl Agroecosyst

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Diversity of farming activities may increase income stability and reduce risks to resourcepoor households, while integration-using the outputs of one activity as input in another activity-may reduce dependency on external resources. In practice, diversity and integration are poorly defined, and there is no method to characterise them, hampering the exploration of their benefits. We introduce a method based on network analysis (NA) to assess the diversity and integration in farm household systems by using the Finn cycling index to characterise integration of farming activities, and the average mutual information, and the statistical uncertainty (H R ) to characterise diversity of flows. We used nitrogen (N) flows in an application of NA to crop-livestock systems of the highlands of Northern Ethiopia. N recycling was low (FCI \ 3%) in these systems independently of the farm type. Even with improved N management FCI was lower than 10%. Since large amounts of N are withdrawn from the system with the harvests, there are relatively few opportunities for recycling. The diversity in N flows increased from the poor to the wealthier farm households, but differences were small. The wealthier farm households did not recycle more N than the relatively less diverse and poorer farm household. The definition of the system and compartments boundaries must be made explicit in any application of the method as these strongly affect the results. NA appears useful to assess the effects of farm management practices on system performance and to support discussions on diversity and integration of agro-ecosystems.

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Section: Indicators To Assess Diversitymentioning

confidence: 99%

Analysing integration and diversity in agro-ecosystems by using indicators of network analysis

Rufino

Hengsdijk

Verhagen

2009

Nutr Cycl Agroecosyst

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“…A i quantifies the level of system activity and the degree of its organization and development (Ulanowicz, 2000) and it is sensitive to environmental changes (Mageau, Costanza & Ulanowicz, 1998). A i is calculated by Ulanowicz and Norden (1990) as follows:…”

Section: Indicators Of Organization and Degree Of Ordermentioning

confidence: 99%

Untitled

Hernández‐Padilla

Ruiz-Barreiro

Salcedo-Bojórquez

et al. 2017

Turk. J. Fish. Aquat. Sci.

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Opisthonema libertate (Pacific thread herring) and Cetengraulis mysticetus (Pacific anchovy) are the two most important herring stocks exploited in the south-eastern Gulf of California (SGC). The certification of these stocks is currently planned for achieving sustainable fisheries. This study analysed the role of these two species in the structure, organization and functioning of the ecosystem in this region. Twenty-four indicators of the ecosystem's structure and its organization were obtained based on the output of an Ecopath model of the SGC. The relationships of the functional groups with the ecosystem's indicators were identified using multivariate statistical techniques, and the results indicated similar roles for the Pacific thread herring and the Pacific anchovy in the ecosystem of the SGC. Both species make large contributions to the maintenance of the ecosystem's order (i.e., its structure and organization). These results are directly related to one of the criteria that are evaluated by the Marine Stewardship Council's certification process. Defining the remaining biomass level at sea after fishing would guarantee the sustainability of fisheries in the ecosystem.

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“…According to this concept, a mature type ecosystem is more protected and has stability and quality. Trophic network analysis can be used to quantify the health, integrity and maturity of ecosystems (Christensen, 1995;Christensen and Pauly, 1998;Ulanowicz, 2000) and also help to evaluate the magnitude of stress imposed on an ecosystem by fisheries and global changes (Mageau et al, 1998). Research efforts using trophic network analyses in ecology have produced methodological, theoretical and empirical advances and development of software packages for ecological trophic analysis.…”

Section: Introductionmentioning

confidence: 99%

Preliminary trophic network analysis of subalpine Lake Annecy (France) using an Ecopath model

Janjua¹,

Gerdeau×²

2009

Knowl. Managt. Aquatic Ecosyst.

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Lake Annecy is the second largest natural lake in France, with intensive commercial and recreational fisheries. However, there is limited knowledge of its trophic interaction. A preliminary Ecopath model was fitted to study the trophic interaction in the lake using the available data on most of the ecosystem compartments. Fourteen functional groups were used in the present analysis. Most of the consumers have ecotrophic efficiency from 0.3 to 0.6. The results show that flow from detritus is as important as flow from primary producers. The overall transfer efficiency of the system is 9.6. The primary production/respiration (P p /R) ratio, which is 3.253, shows that Lake Annecy's ecosystem is comparatively mature. The gross efficiency of fisheries is 0.001173. Catch trophic level and percentage of primary productivity required for catch show that fishery in Lake Annecy is stable. The values of ascendancy (31.2) and overhead (68.8) show the stability of the ecosystem. Mixed trophic analysis indicates that zoobenthos have a positive effect on most of the fish functional groups. This preliminary model can be helpful to pinpoint the gaps in the present knowledge about Lake Annecy. RÉSUMÉAnalyse préliminaire du réseau trophique du lac d'Annecy avec le modèle Ecopath Le lac d'Annecy est le second plus grand lac naturel de France avec une importante pêcherie commerciale et amateur. Toutefois les connaissances sur les interactions trophiques sont limitées. Le modèle Ecopath a été ajusté pour étudier les interactions trophiques dans le lac en utilisant les données disponibles sur la plupart des compartiments de l'écosystème. Quatorze groupes fonctionnels ont été utilisés dans cette analyse. La plupart des consommateurs ont une efficience écologique qui varie de 0,3 à 0,6. Les résultats montrent que le flux de détritus est aussi important que le flux des producteurs primaires. L'efficience globale du système est de 9,6. Le rapport production primaire/respiration (P p /R) de 3,253 montre que le lac d'Annecy est relativement mature. L'efficience brute de la pêcherie est de 0,001173. Le niveau trophique des captures et le pourcentage de la production primaire requis par ces captures montrent que la pêcherie au lac d'Annecy est stable. Les valeurs de l'« ascendancy » (31,2) et de l'« overhead » (68,8) montrent la stabilité du système. L'analyse trophique montre que le zoobenthos a un effet positif sur la plupart des groupes fonctionnels de poissons. Ce modèle préliminaire peut être utile pour mettre le doigt sur les lacunes dans les connaissances actuelles sur le lac d'Annecy.

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Quantifying the trends expected in developing ecosystems

Cited by 71 publications

References 30 publications

Analysing integration and diversity in agro-ecosystems by using indicators of network analysis

Analysing integration and diversity in agro-ecosystems by using indicators of network analysis

Untitled

Preliminary trophic network analysis of subalpine Lake Annecy (France) using an Ecopath model

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