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Leaves that develop on seedlings, young saplings or regenerative shoots of many eucalypt species are strikingly different in morphology from the typical leaves of more mature plants; a developmental pattern known as heteroblasty. We measured dimorphism between juvenile and adult leaves in shape and size, leaf mass per unit area, and vein frequency in a continent-wide sample of Angophora, Corymbia and Eucalyptus species. We tested whether heteroblasty in this group is an adaptation to shading by comparing the degree of juvenile–adult leaf dimorphism with the canopy closure (measured by the leaf area index) of the habitat in which species occurred. No pattern emerged for heteroblasty in leaf shape and size or leaf mass per unit area, but there was a significant relationship (accounting for phylogenetic relationships) between the degree of juvenile–adult dimorphism in vein frequency and habitat leaf area index. Juvenile leaves tended to have more widely spaced veins than adult leaves of the same species, in regions with more closed vegetative canopies. This evidence suggests that eucalypt heteroblasty is, at least in part, a hydraulic adaptation to the different conditions faced by younger and older plants in higher productivity regions with denser vegetation.

1. Faunal responses to plant invasions and their managed removal can expand our understanding of the nature of disturbance and the success of restored plant communities.2. We examined how bird communities responded to the presence and removal of the invasive understorey tree Pittosporum undulatum Vent. (sweet pittosporum) in matched woodland areas in temperate south-eastern Australia that were free of P. undulatum invasion, were invaded, or had been cleared up to 14 years prior to our sampling.3. Overall bird species richness and individual abundance were insensitive indicators, as neither were significantly affected by the presence or removal of P. undulatum.However, richness and abundance were sharply lower in and beneath the P. undulatum canopies compared to the forest overstorey, pointing to a large structural modification by the invader. Bird community composition changed in fairly consistent ways at multiple sites upon invasion by P. undulatum, changes that were partly but not completely reversed by removal of P. undulatum. The suite of functional traits of the birds present at the sites was disrupted in idiosyncratic ways at sites invaded by P. undulatum and only very weakly restored upon clearing of P. undulatum. Functional and diversity indices are dependent on the type of management implemented.4. We propose that a more nuanced approach to management such that some of the invaded forest in neighbouring areas is retained while new trees become established in the cleared areas, providing access to suitable habitat for birds during the transition phase. Such measures are challenging in terms of management and funding but are necessary to maintain avian diversity during and after restoration processes.

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