Structuring factors of the phytobenthos community along a mountain headwater (Kalkalpen National Park, Austria)
Niedermayr, Romana; Schagerl, Michael
published: Jun 1, 2010
ArtNo. ESP141017702002, Price: 29.00 €
The phytobenthos community of a carbonate headwater and its springs were studied in the Kalkalpen National Park (Austria). The investigated rivulet Almbach is located at a traditionally farmed mountain pasture. Two springs, one of them fenced in to prevent livestock access, and two more sites from the headwater were sampled from May to October 2005. Whereas diatoms dominated the fenced spring, chlorophytes reached highest biomass at the spring with livestock access. A Discriminant Analysis revealed three functions based on nitrate, phosphorus and channel width, which classified 100 % of the sites correctly. Indicator taxa - regarded as highly indicative of a particular site when they are mainly found at that site and are present in a large number of its sample units - were mainly detected at the cattle-free sites. Both springs differed significantly from the rivulet sites and from each other concerning physico-chemical parameters, algal community structure, biomass and seasonal development. Canonical Correspondence Analysis was used to analyze the phytobenthos community pattern along environmental gradients. Phosphorus, benthic ash-free dry mass and pH had the highest influence on the first two axes, which explained 78 % of taxa-environmental variation. A negative impact of pasturing on the sensitive high mountain headwater system was detected because of reduced bank stability through trampling, decreased canopy cover and increased nitrogen input. These factors caused an atypical, chlorophyte-dominated phytobenthos community with both low algal diversity and evenness.