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1
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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
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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.
2

Impact of humic substances on Sphagnum denticulatum habitats

100%
Banas K.
Acta Societatis Botanicorum Poloniae
|
2002
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tom 71
|
nr 1
3

The effect of the ploidy level and genetic background of Sphagnum denticulatum on its morphology and ecological requirements

84%
Melosik I.
Oceanological and Hydrobiological Studies
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2009
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tom 38
|
nr 4
153-164
4

Role of humic substances in the determination of Sphagnum denticulatum Brid. and Myriophyllum spicatum L. habitat conditions

84%
Szmeja J., Bazydlo E., Uruska A.
Polish Journal of Ecology
|
2001
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tom 49
|
nr 2
5
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The disintegration of populations of underwater plants in soft water lakes enriched with acidic organic matter

84%
Szmeja J., Bociag K.
Acta Societatis Botanicorum Poloniae
|
2004
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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).
6
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Distribution and habitat conditions of the phytocoenoses of Sphagnum denticulatum Bridel and Warnstorfia exannulata [B.,S. and G.] Loeske in Polish Lobelia lakes

84%
Szankowski M., Klosowski S.
Acta Societatis Botanicorum Poloniae
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2004
|
tom 73
|
nr 3
Phytosociological and habitat studies of Sphagnum denticulatum and Warnstorfia exannulata phytocoenoses from Polish Lobelia lakes have been conducted. The present results were compared with data on Isoetes lacustris community. It is demonstrated that both communities of mosses are distinct with respect to their floristic composition. Moreover, they differ significantly from the patches of I. lacustris with regard to many properties of water and substrates. The phytocoenoses of S. denticulatum are associated with softer waters, poorer in Ca2+, Na+, NH4+ and dissolved organic matter, but richer in total Fe than those of I. lacustris. They are also distinguished by lower values of electrolytic conductivity. The substrates they inhabit are more strongly hydrated and richer in organic matter, total N, dissolved SiO2, Ca2+ and Na+, but poorer in PO43-. The W. exannulata phytocoenoses are also confined to softer waters with lower Ca2+, NH4+ and dissolved organic matter contents than those of I. lacustris. Their substrates are more strongly hydrated and have higher contents of organic matter, total N and Na+ but lower amounts of PO43-. In addition the waters of W. exannulata phytocoenoses are characterized by higher pH values and lower concentration of dissolved SiO2. The substrates are less acidic and richer in NO3-, but poorer in total Fe. The differences between the habitats of the S. denticulatum and W. exannulata phytocoenoses are also distinct. The former inhabit more acidic waters, richer in dissolved SiO2 and total Fe, but with lower values of electrolytic conductivity and concentration of Na+. Their substrates are distinguished by higher contents of organic matter and Ca2+, as well as by lower amount of NO3-. In view of the fact that the above phytocoenoses of mosses are distinct with respect to their floristic composition and are associated with specific habitats in which they form dense mats close to the bottom of the lake, they should be classified as distinct associations (Sphagnetum denticulati and Warnstorfietum exannulatae) in the system of aquatic communities (Class: Utricularietea intermedio-minoris).
7

Effect of light competition with filamentous algae on the population dynamics and development of the moss species Warnstorfia exannulata in a softwater lake

67%
Szmeja J., Bociag K., Mierdalski M.
Polish Journal of Ecology
|
2010
|
tom 58
|
nr 2
The effect of a massive bloom of filamentous algae on the long-term abundance dynamics of the moss Warnstorfia exannulata (B., S. & G.) Loeske was studied in an acidic lowproductivity lake in NW Poland. Individuals were counted on 4 experimental plots, 1 × 1 m each, at a depth of 2.5 m. The studies were conducted for 36 months, every 30 days, by SCUBA diving. Over the three years the seasonal changes in water pH, conductivity, HCO₃⁻ concentration, sediment hydration and pH were not statistically significant (P> 0.05), and light intensity was higher in winter than in summer. Over the three years 4 consecutive stages of population development were observed: regeneration, stabilisation of abundance (fluctuations), regression and repeated regeneration. These stages appeared and lasted at different temperatures and light intensity. The greatest monthly increase in abundance took place in summer and lasted until the beginning of autumn under conditions of high temperature and relatively low light intensity. Long-term abundance variations were strongly correlated with the appearance of filamentous algae, less strongly with the dynamics of the dominant species (Sphagnum denticulatum), and the least with water temperature, light intensity, water and sediment pH, conductivity and HCO₃⁻ concentration. As a result of a massive bloom of these algae, light intensity decreased in the water, Warnstorfia shed its leaves, and then the entire population disappeared. In winter that year it began to regenerate from vegetative propagules (leafless shoots), which were the remains of individuals growing before the filamentous algae appeared. In softwater lakes such massive algal blooms are a common phenomenon which limits light transmission to the substrate and as a result leads to changes in the submerged vegetation structure, especially that of bryophytes.
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