Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Polish Journal of Ecology

2 2004

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: Luronium natans

Sortuj według:

Ogranicz wyniki do:

Effect of pH, dissolved organic carbon and total phosphorus concentrations on selected life history traits of Luronium natans (L.) RAF.

Bazydło E., Szmeja J.

Polish Journal of Ecology

2004

Vol. 52, nr 2

191-200

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 [mi]g 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 TP3 > 20.1 [mi]g dm^-3 and DOC > 6 mg C dm^3, 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 local populations of Luronium natans is a decrease of pH below < 5.0.

Effect of environmental conditions on the populations of Luronium natans (L.) RAF

Bazydło E.

Polish Journal of Ecology

2004

Vol. 52, nr 2

181-189

The structure (aggregations distribution, density, age structure) of Luronium natans L. (Raf.) populations has been studied in 21 lakes in the Pomeranian Lakeland (NW Poland), where the highest population density of this species is found in slightly acid (pH 6-7) waters, poor in DOC (<6.0 mg C dm^-3) and phosphorus (<30.0 [mi]g TP dm^-3). Luronium natans reproduces mainly vegetatively and prefers shallow (1-2 m), mineral-organic (5.1-10% C) substrates. Seedlings represent about 10% of a population. High levels of pH (pH>8.0), concentration of carbon (>6.0 mg C dm^-3) and phosphorus (>30.0 [mi]g TP dm^-3) impede the population growth. Under such conditions population densitymay be lower by as much as 80-90%, aggregation size smaller, and the proportion of generative stems higher. Luronium natans aggregation size depends on the depth: the deeper the location - the larger and denser the aggregation, the shallower the location - the larger the fraction of generative individuals (up to 98% of the population).