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The effects of small-scale impoundments and bank reinforcing on fish habitat and composition in semi-natural streams

Monaghan K., Fonseca M., Domingues I., Soares A.

Polish Journal of Ecology

2008

Vol. 56, nr 4

647-657

We studied the fish assemblages of thirty one, 2nd-4th order "least-impacted" streams with a varying degree of low-level management in central Portugal, using a standardised survey to document the river habitat. Channel, banks and riparian landuse, described separately according to principal component scores, were significantly related to altitude, slope and management intervention. Species diversity was low, represented by four endemic, four pan-European and one exotic species. TWINSPAN classification distinguished 3 community types, characterised by their dominant species: trout (Salmo trutta L.), chub (Leuciscus carolitertii Doadrio) and "roach" (Squalius alburnoides Steindachner and Chondrostoma oligolepis Robalo). Community types were associated with environmental differences with PC Channel scores higher at trout sites compared to other classification groups, whilst PC Bank-1 scores, temperature and conductivity were significantly different at trout compared to "roach" sites. Ecologically important habitat features were, in turn, related to landscape (map-derived) parameters and the extent of channel and bank management. The mis-classification of sites in discriminant analysis was related to management intervention, indicating the potential difficulty in the assignment river-community types for the biological monitoring of fish communities in these stream types.

Trójkąt Osanna jako forma prezentacji danych statystycznych i legenda map tematycznych

Korycka-Skorupa J.

Polski Przegląd Kartograficzny

2007

T. 39, nr 4

340-353

W artykule przedstawiono różne możliwości zastosowania w kartografii trójkąta Osanna, zwanego również wykresem trójkątnym. Po krótkim zarysowaniu historii tego sposobu prezentacji, szczegółowo omówiono jego właściwości oraz zasady konstrukcji. Pokazano różne sposoby czytania i interpretacji trójkąta, a także kartograficzne przykłady jego zastosowania.

Osanna Triangle, also known as a triangular diagram, is a specific method of data presentation, used in statistics and socio-economic cartography to present phenomena of three-fold structure. This type of diagram presents which part of the whole is composed by particular elements, what the proportion of those elements is and how similar elements in two or more various entities compare. It is used as an independent presentation form as well as a legend of thematic maps. The term 'Osanna Triangle' comes from a name of a German mineralogist, Alfred Karl Osanna (1859-1923), who analyzed minerals according to their atomic and particle contents. The chemical classification of rocks, which he prepared, was presented on triangular diagrams. Osanna Triagle is a diagram of relations of three variables placed in a system of three coordinates. The location of each point within the triangle is determined by three coordinates, read at its sides, on heights led from its angles or on lines of the grid (fig. 2). Proper interpretation of the diagram bases on the understanding of significance of points' placement within the triangle. Often the triangle is divided into smaller units (triangles, rectangles) in order to establish areas where points with similar features occur (fig. 4). This diagram can be used to present the structure of a given statistical set and also conclusions about the whole set (fig. 5). Also, it can show the dynamics of a phenomenon through changing value of particular elements of the structure in time (fig. 6). Osanna Triangle is frequently used as an explanation, map legend, most often related to a choropleth presentation. Basing on a triangular diagram one can conclude about the distribution of phenomenon's value and determine choropleth classes. Application of an unorthodox triangular set of coordinates, to which we are not used, makes the perception of Osanna Triangle rather difficult. Perhaps this is why this method of data presentation is not commonly used.