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Wyszukujesz frazę "natural species" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Vimba Vimba vimba (L.) from the Rega River - support of natural spawning in 2004-2008 and the natural population
Certa Vimba vimba (L.) z rzeki Regi - wspieranie naturalnego tarła w latach 2005-2008 a naturalna polpulacja
Autorzy:
Tanski, A.
Czerniejewski, P.
Keszka, S.
Pender, R.
Pilch, E.
Powiązania:
https://bibliotekanauki.pl/articles/85115.pdf
Data publikacji:
2011
Wydawca:
Akademia Pomorska w Słupsku
Tematy:
vimba
Vimba vimba
Rega River
natural spawning
natural population
biogeography
threatened species
stocking
restoration
spawning site
Opis:
The paper reports results of a study on the population of vimba in the Rega River aimed at localisation of the spawning sites and support of the natural reproduction by stocking. The spawning sites were localised with the help of electric catching and the coordinates were determined by GPS units. The fish caught to be used for artificial spawning (145 individuals) were measured (l.t. and l.c.) using an electronic calliper coupled with a PC unit. The sex of the fish was identified and on the basis of scale analysis the age and rate of length and mass increase were estimated. The backcalculation readings were made using the Rosa Lee method. The model of growth was established on the basis of the von Bertalanffy formula. Comparisons of groups of fish were drawn with the help of the nonparametric Mann Whitney U test. Correlations between variables were evaluated by analysis of regression, while the significance of the correlation coefficient was checked by t test. The rate of vimba mass increase was calculated using the modified von Bertalanffy formula was found to be described by Wt = 1215.103[1-e-0.133609(t+0.57322)]2.7559. The spawning sites of vimba localised in the Rega River section between Gryfice and Trzebiatow were concluded to be good sources of spawners for artificial spawning and the number of spawners caught in this section of the river ensures continuation of vimba restitution in the Rega River. The hitherto stocking measures aimed at restoration of vimba population have brought satisfactory results as evidenced by the age structure of the fish caught in the electric fishing in 2008.
Źródło:
Baltic Coastal Zone. Journal of Ecology and Protection of the Coastline; 2011, 15
1643-0115
Pojawia się w:
Baltic Coastal Zone. Journal of Ecology and Protection of the Coastline
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variation in acorn traits among natural populations of Quercus alnifolia, an endangered species in Cyprus
Autorzy:
Anagiotos, G.
Tsakaldimi, M.
Ganatsas, P.
Powiązania:
https://bibliotekanauki.pl/articles/41714.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
variation
acorn trait
natural population
Quercus alnifolia
endangered species
seed germination
desiccation
golden oak
plant morphology
population variability
Cyprus
Opis:
Quercus alnifolia is an endemic species in Cyprus, and it is rated as Vulnerable (VU) in the Red List of Oaks. Although Q. alnifolia has a great ecological importance, there are only few studies about this species. In this work we have studied the natural variability of this species by analyzing acorn dimensions, acorn mass, length of embryo, moisture content of acorns and seed germinability among the seven acorn provenances, collected in Cyprus. We also determined the seeds responses to drying. Germination trials were also carried out, and differences in seed germination among populations were examined. Rate of water loss and its effect on seed germination was also estimated by application of specific desiccation treatments. The results showed that acorn characteristics significantly differed between the populations, following a general trend to reduce their dimensions and mass with the altitude increase. Seed germination was high for all studied populations, and germination behaviour was similar for all populations. Desiccation of acorns below 35% resulted in a great reduction of seed germination capacity.
Źródło:
Dendrobiology; 2012, 68
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Does vegetation impact on the population dynamics and male function in Anemone sylvestris L. (Ranunculaceae)? A case study in three natural populations of xerothermic grasslands
Autorzy:
Denisow, B.
Wrzesien, M.
Powiązania:
https://bibliotekanauki.pl/articles/57860.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
vegetation impact
population dynamics
male
function
Anemone sylvestris
Ranunculaceae
natural population
xerothermic grassland
rare species
shrub
plant expansion
pollen mass
pollen viability
seed set
Opis:
In Poland, like in other parts of Central Europe, dry grasslands significantly contribute to the biodiversity of both fauna and flora. Anthropogenic pressure impair many species of xerothermic habitats, and several populations face an increased risk of extinction. The goal of the study was to define factors that may affect the size of wild populations of Anemone sylvestris L., a protected species in Poland, with both a short- and long-term perspective, and to examine the influence of vegetation changes on the density, the abundance of flowering and male function (pollen production, pollen viability), as well as seed set. In situ observations were performed in 2005-2006 and 2011-2012 in three populations located on the Lublin Upland, SE Poland. The reduction in population density and A. sylvestris blooming was exacerbated by the expansion of the shrubs, but not by Brachypodium pinnatum. Male characteristics of A. sylvestris, i.e. pollen amount per multi-staminate flowers or pollen viability appeared to decrease under pressure of shrub competition. Populations with limitation of male function had impaired degree of seed set. Various consequences for the functioning of populations within a metapopulation system can be expected due to substantial qualitative and quantitative disorders in pollen traits. It is crucial that successful recovery programs for A. sylvestris primary should aim to conserve and manage the habitat.
Źródło:
Acta Societatis Botanicorum Poloniae; 2015, 84, 2
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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