Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Australie → 2015 → Avian diversity in arid Australia : patterns in species richness and composition across varied assemblages and environments

Australian National University (2015)

Avian diversity in arid Australia : patterns in species richness and composition across varied assemblages and environments

Reid, Julian Robert Wishart

Titre : Avian diversity in arid Australia : patterns in species richness and composition across varied assemblages and environments

Auteur : Reid, Julian Robert Wishart

Université de soutenance : Australian National University

Grade : Doctor of Philosophy (PhD) 2015

Description partielle
I studied avian diversity in three regions of arid Australia, namely Cooper Creek (northern South Australia), and the MacDonnell Ranges and Lake Mackay in the southern Northern Territory. The primary objectives of the study were to document the major correlates of bird species richness and compositional turnover, as measures of alpha and beta diversity, and to see if gradients in both covaried. I tested the hypotheses that primary productivity has ultimate control on bird diversity and vegetation proximate control. Cooper Creek flows intermittently and because of large transmission losses, a naturally steep gradient of declining annual discharge occurs longitudinally, with predictable consequences for the structure and composition of riparian vegetation. A dominant riparian tree, river red gum, and at least eight species of birds reach the limits of their distribution in the study area in response to the main hydrological gradient. Bird species richness declined laterally, from riparian to outer floodplain, and longitudinally downstream, and the main trends in compositional turnover followed these gradients. The distribution and abundance of red gums and coolibah were found to be the major determinants of avian diversity on the floodplain. Bird species richness decreased, and assemblage composition changed, from upstream riparian areas to outer parts of the floodplain and lower riparian reaches. The decrease in the stature and cover of riparian vegetation with distance downstream resulted in downstream bird assemblages forming significantly nested subsets of rich upstream assemblages. Steep topographic gradients in the MacDonnell Ranges allowed bird diversity responses to be examined at small spatial scales. Bird species richness was highest in the riparian zones of major streams and lowest on the upper slopes and tops of mountains dominated by spinifex.

Présentation

Version intégrale (64 Mb)

Page publiée le 28 janvier 2021