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Doctorat
Australie
2001
The impact of grazing and exotic invasion on the persistence of native grassland
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.
Page publiée le 29 janvier 2021