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Accueil du site → Doctorat → Allemagne → 2007 → Avian species richness and assemblages in relation to vegetation and water availability in arid central-eastern Australia

Carl von Ossietzky University Oldenburg (2007)

Avian species richness and assemblages in relation to vegetation and water availability in arid central-eastern Australia

Schneider Nicole Anja

Titre : Avian species richness and assemblages in relation to vegetation and water availability in arid central-eastern Australia

Auteur : Nicole Anja Schneider

Université de soutenance : Carl von Ossietzky University Oldenburg

Grade : Diploma-Thesis 2007

Résumé
Riparian zones are recognised for their contributions to local and regional biodiversity and their importance for avian diversity has been demonstrated within a range of vegetation types. In semi-arid and arid environments, where there is a marked contrast between the riparian and the adjacent landscape matrix, riparian zones are landscape elements of relative resource stability. Although many studies have investigated how vegetation and surrounding land-use influences avian species richness, abundance, and assemblage composition, relatively few have assessed how avian species richness is affected by water and changes in its availability within arid regions. Water related variables (e.g. precipitation, water-energy variables) have been identified as the drivers of large-scale species diversity patterns and within arid environments water will especially gain of importance in the light of climatic changes.
I investigated the effect of accessible surface water and precipitation, as well as vegetation composition on bird species richness and assemblage composition at riparian and adjacent habitats in north-western New South Wales, Australia. Vegetation differed distinctly between riparian and non-riparian sites, but not within riparian habitats. Avian species richness depended on the availability and size of surface water but was not affected by precipitation patterns. Species richness declined with distance from open water, not only in the desert but also within the riparian environment. Structural vegetation complexity of riparian woodlands was also a strong determinant of bird species richness. A canonical correspondence analysis confirmed that bird assemblages were influenced strongly by water and vegetation structure. The distribution and abundance of bird species changed with distance from water, such that more moisture dependent species were present in the vicinity of water while only a few species increased in number at greater distances.
The differentiation between avian species richness and assemblages at riparian water sites and the surrounding arid landscape reveals the marked ecological value of these habitats in contributing to local and regional biodiversity. Water is a critical resource in determining regional avian diversity, although the compositional structure of bird communities has been affected by pastoral grazing regimes and water provision.

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Page publiée le 3 janvier 2012, mise à jour le 12 mai 2019