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Factors affecting composition of gravel bar vegetation in middle reach of a lowland river

100%

Skornik S., Meznaric M., Kaligaric M.

Polish Journal of Ecology

2017

tom 65

nr 2

In this study, we investigated plant communities in relation to site-specific morphological properties and sediment structure on gravel bars along the middle Drava River in Slovenia. We sampled 143 plots of 5 × 5 m using species cover-abundance estimates. In addition, we considered the following habitat physical variables: elevation above the water line, texture of the substrate (silt, sand, gravel content) and bar age. Based on TWINSPAN method, we distinguished four vegetation types: (G1) xerophilic and thermophilic ruderal stage; (G2) stage with sparse and herb-rich ruderal vegetation with species of semi-dry grasslands; (G3) initial vegetation stage of frequently disturbed mesotrophic and eutrophic sites and (G4) tall-willow stage. The most important factors determining a bar's vegetation were elevation and gravel content. Our study shows that gravel bars of the middle Drava river system form a suitable habitats for species-rich plant communities. Their diversity is a function of high spatial heterogeneity coupled with the opposing forces of stress and disturbance.

In stream hydraulics, granulometry and sediment chemistry of a mountain stream within gravel bar regions

84%

Radecki-Pawlik A.

Electronic Journal of Polish Agricultural Universities. Series Environmental Development

2004

tom 07

nr 2

The paper presents the results of examination some basic granulometric and hydraulic parameters such as changes in granulometry, velocity, shear stresses, Froude number, Reynolds number and flow resistance coefficient within the region of two different gravel bars in the mountain stream. The sediment samples were taken from points situated along the bars and from the riverbed in the area where the bars have their influence on the river regime. On the top of the granulometry and hydrodynamics survey there were also the chemical properties of the sediments, including heavy metals, examined. The main conclusion of the paper is that a point bar (developed on the river band) is less stable, than an up-of the obstruction bar (an alternate bar) developed along the river bank. Also there are number of observations connected with the hydrodynamics influence on stream bars formation. The study was undertaken on the Skawica-Jałowiecki Stream in the Polish part of the Carpathian Mountains.

Ograniczanie wyników

1 Electronic Journal of Polish Agricultural Universities. Series Environmental Development

1 Polish Journal of Ecology

1 Kaligaric M.

1 Meznaric M.

1 Radecki-Pawlik A.

1 Skornik S.

1 2017

1 2004

Wyniki wyszukiwania

Factors affecting composition of gravel bar vegetation in middle reach of a lowland river

In stream hydraulics, granulometry and sediment chemistry of a mountain stream within gravel bar regions