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A simple technique of random leaf collecting for biometric studies in a tree stand

The method reflects proportions in the number of leaves of different sizes and shapes, which appear in a tree stand. The study was carried out during autumn leaf fall, in about a hundred years old tree stand, dominated by beech. Leaves were collected three times, altogether with assessment of foliage density. For all gathered leaves, the width and length were measured and the data were statistically analyzed. Differences among all three samples were significant, which indicates different size of falling leaves in the following periods. Thus, only the research carried on at the end of leaves falling allows collecting a sample which represents proportions among leaves of different sizes in the tree stand.

Abstract

This paper presents the results of studies carried out on Ptelea trifoliata populations in the Wyszków Forest District in 1998 and 2013. P. trifoliata is a native species of North America (United States of America, northern part of Canada) and has a wide ecological range. However, it prefers fertile, wet soils and moderate light. In Europe, it is planted for its decorative value and is mainly found in synanthropic habitats (parks, graveyards, roadsides, fortifications) in Poland. The station of P. trifoliata is situated in the oak-hornbeam forest, Tilio-Carpinetum typicum, with a significant fraction of the stand consisting of Pinus sylvestris. Hop trees occur mainly along forest section lines and are rarely found inside the sections. In the last 15 years, an increase in the number and size of P. trifoliata clusters has been observed. The species spreads along forest section lines, which form a convenient migration route by creating favourable conditions for the germination and growth of seedlings (good access to light, fragments of bare soil). The presence of new individuals far from the pre-existing clusters indicates that the generative way of propagation dominates. Biometric measures indicate significant differences in length and width of whole leaves as well as leaflets, with leaves and leaflets of vegetative specimens significantly larger than generative ones.

As a consequence of the high rate of P. trifoliata expansion along forest section lines and occurrence of single specimens inside the forest sections, we assume this species to be potentially invasive.

Abstract

Oligomely is a type of developmental anomaly occurring in embryos of the spider Tegenaria atrica C.L. Koch under the teratogenic influence of temperature. This anomaly is of metameric origin, as it results from a disorder of metamere formation on the germ band during embryogenesis, resulting in the absence of one half or the whole metamere. In such a case, one or more appendages are missing on one or both sides of the body in a spider leaving a chorion. This anomaly induces changes both in the anatomical structure and exoskeleton of a spider (deformation of carapace and sternum). Carapace length and sternum area were measured, as well as the duration of the subsequent nymph stages of oligomelic individuals with one of the walking appendages missing (always on the right side of the body) was recorded. The consecutive nymph stages of oligomelic individuals lasted for a much shorter time compared with control specimens. This acceleration of development is probably to offset losses incurred during embryogenesis. In the early postembryogenesis, oligomelic specimens exhibited shorter carapace length and smaller surface area of the sternum compared to control individuals, which resulted from the lack of half of the metamere corresponding to the missing leg. However, in older nymph stages, a strong tendency for the faster growth of both carapace and sternum was observed, which can be defined as a compensatory growth increase making up for the losses caused by the anomaly.

Morphology of the Common Gudgeon, Gobio Gobio (L.) Sensu Lato, from the Vistula River Drainage in the Context of Recent Literature Data (Teleostei: Cyprinidae)

The common gudgeon Gobio gobio (L.) is considered to be highly variable and to show very good adaptability to local environmental conditions. The most recent studies show that the traditional notion of the G. gobio species covers a number of highly similar but distinct species that can be distinguished based on detailed analysis of morphometric characters.

This work presents the results of biometric studies on common gudgeons from two small rivers in the Vistula River drainage. The study has shown several biometric differences between the analyzed populations. Whether the two populations of the common gudgeon represent distinct species or are only evidence of intraspecific variation will be clear once the required comparative material has been gathered. Therefore, in accordance with the international trend, these populations should be treated as Gobio gobio (L.) sensu lato (= G. gobio (L.) complex).

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, Coregonus albula L, from lakes Drawsko and Pełcz - Acta Ichthyol. Piscat. 32: 53-69. Czerniejwski P., Wawrzyniak W. 2006 - Management of vedance ( Coregonus albula ) in the lakes of northwest Poland in the late twentieth and early twenty-first centuries - Arch. Pol. Fish. 14: 105-121. Filipiak J., Raczyński M. 2000 - Lakes of Polish Western Pomerania; fact sheets - Wyd. AR Szczecin , 255 p. (in Polish). Gąsowska M. 1973 - Comparative biometric study of vendace ( Coregonus albula ) from Polish lakes and some neighboring countries - Rocz. Nauk Rol. 95-H-1: 41-54 (in

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