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Macadamia tetraphylla is a subtropical rain forest tree from fragmented lowlands in eastern Australia. Owing to habitat loss and fragmentation, this commercially important species is vulnerable to extinction. Breeding system and fecundity were investigated in nine populations incorporating three habitat types (moderately disturbed, highly disturbed, and intact) to determine if seed set, seed weight, and genetic diversity are compromised by disturbance. Breeding success was also tested using pollen donors from distant (30–100 km), local (2–3 km), neighbor (10–20 m), and near‐neighbor (< 10 m) sources. Macadamia tetraphylla is weakly self‐compatible but incapable of automatic self‐pollination. Across populations, seed to flower ratios were always < 0.1 percent in open‐pollinated trees and trees from moderately disturbed habitats had the highest fruit production. Outcross pollen produced more seed per raceme than open‐pollinated or self‐pollination treatments. Seed set and seed weights were positively influenced by pollen source with local pollen and distant pollen effecting more or heavier seeds. Germination rates and genetic diversity did not vary significantly in seedlings from different pollen sources. Results suggest a pollen source from at least a 2 km distance is an optimal outbreeding distance; however, many wild populations do not have conspecifics at optimal distances owing to habitat fragmentation. Highly disturbed populations are producing seed but the longevity of these sites is threatened by weed invasions. We conclude that small populations in degraded habitats that are at risk of being overlooked should not be ignored but should be a focus for restoration efforts as they are a valuable asset for the conservation of M. tetraphylla.

In a seminal paper, Crowley (1994a) attributed the decline of Casuarinaceae in Australia during the period of European contact to soil salinization, itself the product of vegetation clearance and raised groundwater levels. However, the post-contact Casuarinaceae decline in the New England area of northeast New South Wales was not associated with salinization. Instead, there is strong evidence that the decline was caused by the preferential use and clearance of these trees by European settlers. Direct human impact must therefore be added to the list of causes of the late-Holocene diminution of Casuarinaceae in Australia.

The Lake Eyre Basin, one of the world's last unregulated wild river basins, covers almost one sixth of the Australian continent, with large areas of connected wetlands (73 903 km 2 ), including floodplains, lakes, waterholes and river channels. Few data existed and so we used literature and government biotic and abiotic data and anthropogenic impacts to assess the conservation risk of the ecosystem as Least Concern (IUCN Red List criteria for ecosystems, version 2.0). This was based on limited distributional change and low levels of degradation or anthropogenic threatening processes. The approach could be applied to ecosystem assessments of other large river basins around the world, given the Lake Eyre Basin occupies one extreme (unmodified) while the Aral Sea (collapsed), previously assessed, occupies the other extreme (highly modified). River flow analysis with available biotic data is critical for risk assessment as well as identification and tracking of long-term threats. Assessment was possible at this large basin scale and appropriate, given the critical importance of connectivity but could also occur at finer spatial scale. Increased diversions for irrigation, mining impacts on floodplains and projected increased temperatures threaten the current status (Least Concern) of the connected wetlands of the Lake Eyre Basin ecosystem.