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

Titre : The impact of grazing and exotic invasion on the persistence of native grassland

Auteur :

Université de soutenance : Australian National University

Grade : Doctor of Philosophy (PhD) 2001

Résumé partiel
This thesis examines how pastoral activity has modified the native grasslands of the Monaro Tablelands, a cool-temperate region with basalt substrates in south-eastern Australia. The impacts of pastoral management, which include increased grazing, increased soil fertility, introduction of exotic plant species and ploughing, have lead to substantial changes in the composition and structure of plant communities in southeastern Australia. Open grassland and grassy woodland communities have been most affected. Many exotic weeds have established and the abundance and richness of native species have declined, with many native species now threatened with extinction. The primary aim of the thesis is to understand how grazing, disturbance and soil resources, each of which vary with topography, have affected the abundance and persistence of native plant species and invasion by exotics. A number of ecological processes and theories are relevant to understanding and predicting changes in plant community structure in relation to variation in grazing and resources. Most theories have focused on the role of small scale interactions between plants, most notably the role of grazing in competitive interactions and the regeneration niche. The outcomes of these processes should vary according to resource supply and the selectivity, intensity and timing of grazing. Other theories have highlighted the importance of regional species pools and evolutionary history in determining community responses to grazing. I applied both approaches to understanding vegetation patterns on the Monaro Tablelands.

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