Woodlands in south eastern Australia are dominated by trees of contrasting functional types. Callitris glaucophylla is a slow growing, obligate-seeding conifer and Eucalyptus species are fast growing, resprouting angiosperms. The success of these functional types is likely to vary with climate and different levels and rates of disturbances along climatic gradients. I examined how climate and disturbances influenced the dynamics of these woodland dominants, by using surveys of varying scales. Regeneration failure of Callitris has led to ageing populations (mid - late 1800s) below 405 mm annual rainfall in the winter rainfall zone. Failure was associated with farms, which graze livestock and where rabbits are common. In contrast, Callitris populations are younger (since 1950s) and expanding on tenures other than farms (roadside, travelling stock routes, State Forests), where livestock grazing levels are low-moderate, and rabbits and fires are less frequent above 405 mm mean annual rainfall. Competition from canopy trees had little effect on the success of Callitris regeneration. Although regeneration under canopy trees had lower densities, were smaller and less likely to be reproducing than those in gaps, they have persisted 50 years after their establishment. In contrast, competition from regeneration had a significant effect on canopy tree resilience during drought.
|Qualification||Doctor of Philosophy|
|Award date||01 Aug 2010|
|Place of Publication||Australia|
|Publication status||Published - 2010|