Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 30

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
1

The ecology of Lobelia dortmanna L.I. The plasticity of individuals within a constant depth interval in oligotrophic lakes

100%
Szmeja J.
Ekologia Polska
|
1987
|
tom 35
|
nr 3-4
2

The ecology of Lobelia dortmanna L.III. The plasticity of individuals along a gradient of increasing depth in oligothropic lakes

100%
Szmeja J.
Ekologia Polska
|
1987
|
tom 35
|
nr 3-4
3

Flora jezior i ich obrzeży południowej części Pojezierza Kaszubskiego

100%
Szmeja J.
Zeszyty Naukowe Wydziału Biologii i Nauk o Ziemi. Uniwersytet Gdański. Biologia
|
1980
|
nr 02
4

Rejestr polskich jezior lobeliowych

100%
Szmeja J.
Fragmenta Floristica et Geobotanica. Series:Polonica
|
1996
|
tom 03
347-367
5
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Changes in the aquatic moss Sphagnum denticulatum Brid. population abundance in a softwater lake over a period of three years

100%
Szmeja J.
Acta Societatis Botanicorum Poloniae
|
2010
|
tom 79
|
nr 2
167-173
Changes in population abundance of submerged Sphagnum denticulatum Brid. were studied in an acidic and oligotrophic lake in NW Poland over three years. Individuals were counted in a moss carpet at a depth of 2.5 m on 4 experimental plots, 1 × 1 m each, every 30 days for 36 months using the SCUBA method. PAR intensity was seasonally variable (in winter higher than in summer). Changes in water pH, conductivity, HCO3- concentration, hydration and sediment pH were statistically insignificant (p > 0.05). In the summer of the second study year the moss carpet disappeared almost completely due to a massive bloom of filamentous green algae. Periods of growth, regression and regeneration were observed in the population. The stabilisation of population size took 24 months and followed the pattern: slight fluctuations, then rapid growth and repetition of slight fluctuations. The first stage lasted nine, the second four and the third nine months. These stages took place irrespective of seasons, temperature or PAR intensity. Each rapid increase in abundance lasted about 30 days, at PAR intensity >20% and water temperature ranging from 11 to 16oC (in winter, spring or autumn). The regression stage brought about by the algal bloom started in the second year (in summer) and lasted six months (until the end of January in the third year). The population regeneration began in winter (in February, water temperature 3.0oC, PAR about 20%, ice cover 0.15 m) and finished with the end of spring. The population of S. denticulatum shows a repetitive pattern of abundance variations, which is seriously disturbed in summer, especially after a warm spring, by a massive bloom of filamentous green algae.
6

The ecology of Lobelia dortmanna L.II. Population structure and dynamics within a constant depth interval in oligothropic lakes

100%
Szmeja J.
Ekologia Polska
|
1987
|
tom 35
|
nr 3-4
7

Evolution and conservation of lobelia lakes in Poland

100%
Szmeja J.
Fragmenta Floristica et Geobotanica
|
1997
|
tom 42
|
nr 1
8

Tendencies of changes in the flora and vegetation structure of Pomeranian lakes under the influence of humic substances

100%
Szmeja J.
Publications of the Department of Plant Taxonomy of the Adam Mickiewicz University in Poznan
|
2000
|
tom 10
9

III międzynarodowa konferencja poświecona środowiskom podmokłym ( Rennes, Francja, 19-23 IX 1988 r.)

88%
Szmeja J.
Wiadomości Ekologiczne
|
1989
|
tom 35
|
nr 2
10

Zagrozenie i ochrona jezior lobeliowych w Polsce

75%
Szmeja J.
Parki Narodowe
|
1994
|
nr 4
11-16
11

Współczesny etap w przemianach roślinności jeziora Druźno

63%
Kluszczynska K., Szmeja J.
Zeszyty Naukowe Wydziału Biologii i Nauk o Ziemi. Uniwersytet Gdański. Biologia
|
1979
|
nr 01
12

Distribution, abundance and environmental conditions of the clonal aquatic fern Salvinia natans (L.) All. in the Vistula Delta (Baltic Sea Region)

63%
Galka A., Szmeja J.
Biodiversity: Research and Conservation
|
2012
|
tom 28
13

Changes in the vegetation of softwater lakes under the influence of humic substances

63%
Bociag K., Szmeja J.
Polish Journal of Ecology
|
2001
|
tom 49
|
nr 4
14
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

The disintegration of populations of underwater plants in soft water lakes enriched with acidic organic matter

63%
Szmeja J., Bociag K.
Acta Societatis Botanicorum Poloniae
|
2004
|
tom 73
|
nr 2
The characteristics of habitats, individuals and populations of four submerged macrophytes, Lobelia dortmanna L., Isoetes lacustris L., Sphagnum denticulatum Brid. and Fontinalis antipyretica Hedw., were studied in 12 soft water oligohumic lakes which had no inflow of allochtonic DOM and the DOC concentration in the water was <4.0 mg C dm-3 and 13 humic lakes enriched with allochthonous dissolved organic matter (DOM) from drained peat bogs and ranging in DOC water concentration from 4.1 to 44.0 mg C dm-3. The analyses of population disintegration were conducted basing on characteristics of individuals (size, habitat, fertility) and populations (aggregation density index, settlement index of the population area). The settlement index of the population area for Lobelia, Fontinalis, Isoetes, Sphagnum decreased from 8.4 to 6.2 g d.w. m-2, 4.6 to 0.01 g d.w. m-2, 85.4 to <0.001 g d.w. m-2 and 39.3 to 7.2 g d.w. m-2, respectively. Similar trends were observed in aggregation density. The general pattern of the disintegration of populations of these species was always similar. It was independent of the source macrophytes drew resources from or their susceptibility to environmental changes. Individuals began to be eliminated from the deep and central parts of the population area. The remainder of the populations, which persist in the shallowest, best-illuminated part of the area, are themselves endangered by disturbances caused by wavy motion. The only populations of submerged macrophytes which can survive in polyhumic lakes under such conditions are those which are resistant to disturbances common in the shallow littoral (Lobelia dortmanna, Fontinalis antipyretica).
15
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

The effect of water conditions on the phenology and age structure of Luronium natans [L.] Raf. populations

63%
Szmeja J., Bazydlo E.
Acta Societatis Botanicorum Poloniae
|
2005
|
tom 74
|
nr 3
The study presents the results of the analysis of development stages of Luronium natans (L.) Raf. depending on water conditions (pH, light, total nitrogen, total phosphorus, organic carbon) in 21 populations in north-western Poland. The fractions of seedlings, juvenile, mature and generative stems, as well as the course of phenological phenomena were determined. Seedlings are sparse and can be found from May to July. Most of them occur in waters ranging from slightly acid to neutral (pH 6.0-7.0) with TP concentrations of 10-20 µg dm-3, TN concentrations < 1.0 mg dm-3 and DOC concentrations of 3.5-5.0 mg dm-3, on a mineral (5-10% OC) and fairly well lit (31-40% PAR) substrate. The generative phase lasts from May to October. The flowering period is between August and mid-September. Only 35.2±9.4% of flowering stems produce fruits. The plant flowers abundantly in waters with total nitrogen concentrations > 1.2 mg dm-3, that is above the level of TN concentrations most favourable to seedlings and both juvenile and mature individuals. TP and DOC concentrations, and light intensity (PAR) do not influence the size of the generative stems fraction in populations. However, sediment structure is of importance in this respect: about 62.9% of stems flower and fruit on a mineral substrate (< 1% OC), whereas only 17.4% do so on an organic one. The results of this study may be useful in the conservation of this endangered European endemic species.
16
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Phenotypic responses to water flow and wave exposure in aquatic plants

63%
Szmeja J., Galka A.
Acta Societatis Botanicorum Poloniae
|
2008
|
tom 77
|
nr 1
Plastic responses of 10 aquatic plant species from 5 rivers and 5 lakes in NW Poland were examined. Chara fragilis, C. delicatula, Potamogeton pectinatus, P. perfoliatus, P. natans, Spirodela polyrhiza, Hydrocharis morsus-ranae, Salvinia natans, Nymphoides peltata and Juncus bulbosus were the subject of research. In the running water of rivers, rhizophytes were generally bigger and they allocated from 0.6% to 58.6% more biomass for anchoring in the substrate than in stagnant water (ox bow lakes). In both flow variants rhizophytes allocated a similar biomass fraction for generative reproduction. On the other hand, under the influence of water flow pleustophytes reduced the mass of an individual (Spirodela by 25%, Hydrocharis 67%, Salvinia 77%) and emergent structures (p<0.001), and the number of sporangia (p<0.001). In both flow variants the input of biomass to generative reproduction was the same (Salvinia), or it was greater in running water (Hydrocharis; an increase from 4.9±1.3% to 15.1±3.6%). Under the conditions of strong wave action, in comparison with the lack of this environmental factor, Chara delicatula was several times shorter (p<0.001). However, it was also stouter, and as a result it had similar mass. In the areas of wave action the plant allocated 88.8% of its mass for anchoring in the substrate, whereas when there were no waves, only 22.7%.
17

Effect of pH, dissolved organic carbon and total phosphorus concentrations on selected life history traits of Luronium natans [L.] Raf.

63%
Bazydlo E., Szmeja J.
Polish Journal of Ecology
|
2004
|
tom 52
|
nr 2
A hypothesis has been put forward that low pH or high concentration of total phosphorus (TP) and dissolved organic carbon (DOC) in the lake water are the factors responsible for observed extinction of the population of Luronium natans (L.) Raf., protected macrophyte species from the group of isoetids. A study was performed on 525 generative individuals collected from 21 lakes in Pomeranian Lakeland (NW Poland) and a correlation between the biometric characteristics and environmental conditions in the lakes was tested. The following life history traits have been analysed: size of individuals, their fecundity and allocation of biomass. The greatest and most fecund individuals grow in the lake water of pH 6.1–7.0, poor in TP (10.1–20.0 µg dm⁻³) and DOC (3.5–6.0 mg C dm⁻³). The allocation of biomass of the individuals growing in the optimum conditions is as follows 46–54% in the leaves, 22–31% in the roots and 20–27% in the rhizome. In the lakes with water of pH < 5.0 or of TP > 20.1 µg dm⁻³ and DOC > 6 mg C dm³, a statistically significant decrease in the size of the individuals and unfavourable changes in the biomass allocation are found. The main environmental factor responsible for dying out of local populations of Luronium natans is a decrease of pH below < 5.0.
18
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
Content available

Mechanical strength of stems in aquatic macrophytes

51%
Bociag K., Galka A., Lazarewicz T., Szmeja J.
Acta Societatis Botanicorum Poloniae
|
2009
|
tom 78
|
nr 3
181-187
In populations of submerged macrophytes, individuals are selected in terms of resistance to the effect of hydrodynamic forces. The aim of this study was to check whether individuals growing in river water are more tensile and bending resistant than plants occurring in places not exposed to flow stress. We determined the ultimate tensile strength of stems in four macrophyte species, Potamogeton natans, P. pectinatus, Batrachium fluitans and Chara fragilis, which occur in two environmental variants: in running (current velocity of 0.1-0.6 m/s-1) and stagnant water. In addition, flexure of P. natans stems from both environmental variants was examined. What is more, the type and arrangement of strengthening structures in stems of the plants under study were determined. Potamogeton natans stems are the most resistant to stretching (15.6±4.7 N), while stems of P. pectinatus (3.3±1.0 N) and Batrachium fluitans (2.6±0.8 N) are less resistant. Chara fragilis (0.6±0.3 N) has the least resistant stems. Batrachium, Chara and P. pectinatus are more resistant to stretching if they occur in a river current, whereas P. natans, in stagnant lake water. Ultimate bending moment of P. natans stems from lakes is also much greater than of stems from a river (9.75•10-3 – 4.25•10-3 Nm as compared to 2.12•10-3 – 1.00•10-3 Nm). The resistance of stems to breaking is directly proportional to the stem and thallus cross sectional areas. On the one hand, in all the studied Cormophyta species, the more resistant stems (in P. natans from stagnant water, in the others from running water) are thicker and characterised by a higher contribution of air spaces in the overall stem cross-section. On the other hand, the stems retain their species specific structure and have a similar proportion of strengthening elements.
19

Diagnoza jezior lobeliowych w zachodniej czesci Pojezierza Pomorskiego

51%
Banas K., Bociag K., Szmeja J.
Badania Fizjograficzne nad Polską Zachodnią. Seria B
|
1997
|
tom 46
83-105
20

Roslinnosc projektowanego nadmorskiego ogrodu botanicznego w Trojmiescie

51%
Faltynowicz W., Picinska-Faltynowicz J., Szmeja J.
Zeszyty Naukowe Wydziału Biologii, Geografii i Oceanologii. Uniwersytet Gdański. Biologia
|
1985
|
nr 06
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.