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EN
The ichnogenus Grammepus, which is inferred to have been made by a winged (pterygote) insect, was differentiated from other ichnotaxa because its largest tracks were nearly continuous, forming two furrows. Otherwise, it strongly resembles the ichnogenus Lithographus. Examination of both ichnogenera indicate that the largest tracks in Lithographus can be very close together, that some specimens of Grammepus lack furrow-like tracks, and that the type specimen of the type species Grammepus erismatus has separate tracks in some places, and furrow-like ones in others. Given the lack of a feature that can consistently differentiate Lithographus and Grammepus, the latter is synonymized with the former. Experiments with the modern cricket Acheta domesticus in sediment of different saturation levels indicate that a single pterygote producer could produce both “Grammepus-” and Lithographus-like morphologies, with the former being formed in wet, soft sediment wherein the legs drag, and the latter being formed in firmer, drier sediment wherein the legs do not drag.
EN
A local population of Pyrus pyraster was studied in dry and warm habitats: xerothermic grasslands Potentillo-Stipetum capillatae and Adonido-Brachypodietum, as well as thermophilous oak forest Quercetum pubescentipetraeae in the forest-steppe Bielinek Reserve (NW Poland). Our aims were to assess: (1) the ability of this species to adapt to extremely dry sites, as a pioneer woody plant; (2) its phytosociological position; and (3) morphological variation and genetic diversity of the local population. The pear trees in Bielinek Reserve seem to reach an optimum in shrub communities of the class Rhamno-Prunetea, but tree age clearly indicates that the grasslands were colonized by wild pear trees already before the shrub communities developed. This indicates that P. pyraster can colonize very dry, eroded sites, such as steep sunny slopes covered by xerothermic grasslands. Wild pear trees form plant communities that are a seral stage followed by forest-shrub communities or thermophilous forests. The species in xerothermic shrub communities of the reserve shows a high constancy. It is also very resistant to extreme temperatures, insolation, drought, and erosion. Its tree-ring width (on average 1.1 mm per year) was strongly related to precipitation and temperature in spring and summer. High precipitation resulted in wider tree rings, while dry years (associated with high air temperature) caused a decrease in tree-ring width. Another significant factor is precipitation in winter, which had a positive influence on tree-ring width. Microsatellite markers revealed a high level of genetic diversity in this population. Our results suggest that wild pear can be recommended for afforestation of areas affected by droughts and disturbed sites in Central Europe. It can be used to increase the heterogeneity of the landscape, e.g. by creation of forest ecotones and for planting along roads and field margins, especially considering the predicted climate change.
EN
This report on Pediastrum privum (Printz) Hegewald in Lake Małe Zmarłe (Tuchola Forest) is only the second for Poland and the first to describe its morphological variability in a natural population. This study was performed using light microscopy (LM) micrographs, together with data on its ecology.
EN
This paper presents a current study on the morphology, genetic variability, and ecological requirements of the gametophytically diploid S. denticulatum (Bryophyta, Sphagnaceae). Its broad variations in morphology and physiology, coupled with its low genetic variability, may be explained by epigenetic remodeling in response to environmental heterogeneity. Phenotypes initiated via a plastic response can be canalized in the stable and predictable conditions on the bottom of Lobelia lakes. The problem of the different development of these isolated populations is a matter for further taxonomic studies and discussion. Taking into account the great physiological tolerance and massive development of S. denticulatum, predominantly in man-made and man-modified habitats, the question arises: how far should we go to protect this species? This is particularly important at sites where it threatens the survival of other protected plants.
EN
The morphological variation of Chara rudis A. Braun oospores was examined in a local population in a deep (43 m), hardwater (34 mg Ca dm[^-3]) and mesotrophic (P[tot] 0.095 mg P dm[^-3], SD 8 m) lake (NW Poland). Two variants of population density and three variants of depth were taken into account. Oospores are 712.8 [plus or minus] 37.6 (600-817) [mi]m long and 452.6 [plus or minus] 34.2 (350-516) [mi]m wide. They have 8-13 ridges. The outer membrane is slightly granulated. The isopolarity index (length/width x 100) is 158.4 [plus or minus] 9.9 (140-190). The variation coefficient varies from 5% for oospore length to around 10% for fossa width. It was shown that the differences between oospores coming from individual depth and density variants are statistically significant. The biggest (733.21 [plus or minus] 33.3 [mi]m) oospores occurred on individuals growing at a depth of 3 m, while the smallest ones (673.3 [plus or minus] 43.4 [mi]m) at 5 m. The oospores from highly dense aggregations (> 50 individuals x 0.1 m[^-2]) were much longer and wider than oospores from scattered (<10 individuals x 0.1 m[^-2]) individuals. The observed intrapopulation variation of oospores can be regarded as a response to environmental changes along the depth gradient.
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