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The spatial distribution of pine mistletoe Viscum album ssp. austriacum (Wiesb.) Volmann in a scots pine (Pinus sylvestris L.) stand in Central Poland

Kołodziejek J., Kołodziejek A.

Polish Journal of Ecology

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2013

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Vol. 61, nr 4

705--714

EN

The evergreen, semi-parasitic pine mistletoe, Viscum album ssp. austriacum (Wiesb.) Volmann, is one of the four subspecies of European mistletoe, Viscum album L. It is frequently encountered on Scots pine communities in Poland. Distribution of pine mistletoe in representative P. sylvestris stand from the central Poland was investigated. The host density and host size to the frequency of Viscum was verified. Within the studied area 46% out of 313 individuals of P. sylvestris trees were infected by mistletoe, among them 78% in low mistletoe infection, 17% in medium and 3% in high infection. Of 1171 infections recorded on pines, 97% were on branches, 4% on the host trunk. The mistletoe individuals had an aggregated pattern of spatial distribution which was mainly explained by the host size. Infected trees are larger than uninfected ones, on average, and within the infected tree population, trees with mistletoe had higher number of dead branches than trees with none infection. Parasitized trees were more prevalent in low-density stands than in high-density stands. Mistletoes occurred mainly on the outer brunches within trees crowns.

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The influence of shadow created by adjacent plants on phenotypic plasticity of endangered species Trollius europaeus L (Ranunculacae)

Kostrakiewicz K.

Polish Journal of Ecology

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2009

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Vol. 57, nr 4

625-634

EN

The assessment of phenotypic plasticity expressed as the response to abiotic and biotic site factors is important for successful conservation of endangered and threathened species. In Poland one of the strictly protected plant requiring an active conservation is globeflower Trollius europaeus L. It is the perennial forb, consisted of numerous dark green, deeply cut basal leaves and generative shoots with flowers composed of several multi-ovulate carpels. The investigations of morphological traits of Trollius europaeus i.e. number and height of generative shoots and basal leaves as well as the production of flowers, multi-follicles and follicles at stem- and cluster levels, were carried out between 2005 and 2008 on two patches of Molinietum caeruleae localized in Kraków vicinity (Southern Poland) and having different height of litter and herb layer. The study plot labelled NS - "not shaded" (2000 m2) was prevailed by perennials with delicate procumbent or erect stems, small-tussock grass or short rosetteforb species. The height of the tallest plant has not exceeded 98 cm, while the litter layer measured from 10 cm to 28 cm. The study plot named SH -"shaded" (6000 m2 ) was characterised by presence of tall perennials as well as grass and sedges forming large compact tussocks. The tallest plants attained 186 cm, whereas the layer of litter reached from 18 cm to 42 cm. In NS plot -32 clusters were observed, whereas in SH plot 39 clusters occurred. In both populations, clusters were situated in close vicinity, forming large aggregations. The number of aboveground units per cluster in both populations were similar. The longer petioles (higher petiole average length), caused by maximization of light capture were noted in SH, than in NS plot. In SH plot higher sexual shoots were also noted as well as greater number of flowers per shoot. Such phenomenon presumably makes the plant more attractive for pollinators and thus pollen receipt and donation. The similar number of flowers and multi-follicles per cluster were observed in both populations, while the greater number of follicles was observed in NS, than in SH plot. Due to morphological plasticity established clusters of T. europaeus might presumably endure among the vegetation cover or adapt to new environmental conditions. It might be considered that making the gaps in vegetation cover and litter can be an effective way for active protection of Trollius europaeus populations.

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Detecting clusters of microcalcifications in high-resolution mammograms using support vector machines

Kurdziel M., Boryczko K., Yuen D. A.

Bio-Algorithms and Med-Systems

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2007

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Vol. 3, no. 6

11--22

EN

This paper presents a new method for detecting clusters of microcalcifications in high-resolution digital mammograms. Using cluster analysis, we have designed a descriptive set of mammogram image features which enables precise recognition of microcalcifications. These features are fed into the Support Vector Machine classifier trained to discriminate between normal image occlusions and deposits of calcium in breast tissue. Initial candidates for microcalcifications, i.e. suspicious regions on a mammogram image, are selected by means of a discrete wavelet transform, image filtering and morphological operations. Once microcalcifications are detected, our algorithm assesses whether they form groups (clusters) and for each such group verifies its diagnostic significance. This verification is performed by employing another, appropriately trained, Support Vector Machine classifier. Accuracy of our system has been evaluated on the Breast Cancer Research Program (BCRP) volumes of the DDSM database. On this largest publicly available databases of mammograms our system achieved a sensitivity of 85.1% with average number of 5.0 false positive detections per image. Such an accuracy is competitive with other published results obtained on the same dataset.

PL

W artykule przedstawiono nową metodę wykrywania skupisk mikrozwapnień na cyfrowych zdjęciach mammograficznych wysokiej rozdzielczości. Zaproponowana metoda korzysta ze zbioru statystycznych cech obszarów zdjęć mammograficznych, zaprojektowanego za pomocą technik analizy skupisk. Tak skonstruowany zbiór cechy umożliwia precyzyjne rozpoznawania mikrozwapnień. Cechy statystyczne obszarów zdjęć mammografi cznych są wykorzystywane przez klasyfikator SVM (od ang. Support Vector Machine) wyuczony do rozróżniania pomiędzy normalnymi strukturami na zdjęciach, a okluzjami sugerującymi obecność mikrozwapnień. Pierwotna selekcja podejrzanych obszarów na zdjęciach mammograficznych prowadzona jest za pomocą dyskretnej transformaty falkowej, szeregu operacji fi ltrowania i morfologicznych przekształceń obrazu. Po wykryciu mikrozwapnień, algorytm ustala, czy tworzą one skupiska. Następnie każde wykryte skupisko oceniane jest pod kątem wartości diagnostycznej. Oceny tej dokonuje kolejny klasyfikator SVM. Skuteczność proponowanej metody została oszacowana na podzbiorze Breast Cancer Research Program (BCRP) bazy danych DDSM. Na tej największej publicznie dostępnej bazie danych zdjęć mammograficznych zaproponowana metoda wykazuje czułość na poziomie 85.1% przy średniej liczbie 5.0 wskazań fałszywie dodatnich na jedno zdjęcie. Wynik ten jest konkurencyjny w stosunku do innych opublikowanych rezultatów uzyskanych dla tego samego zbioru zdjęć mammograficznych.