Conserving biodiversity is usually an important motivation for replanting and restoring native vegetation. It is assumed biodiversity increases will follow owing to 'passive wildlife re-colonisation': animals will flow down a density gradient from surrounding habitat into restored sites. However, restoration projects are frequently opportunistic and biodiversity goals are seldom clearly specified. Consequently, the strategic planning necessary to facilitate passive re-colonisation is often missing, critical processes are not considered, and restoration fails to achieve the desired biodiversity benefits. How can we create landscapes that will be colonised by wildlife? Where should restoration efforts be concentrated? What type of landscape enhancements will be most effective?

I contend this will depend not only on restoration objectives but also on whether restoration simply increases the population size of species already in the landscape or whether it can re-establish previously extirpated species through passive re-colonisation. This distinction is important because restoration actions should reflect the relevant processes. For example, increasing extant populations relates to re-colonisation from within the landscape: important processes include source-sink habitats, metapopulation dynamics and local dispersal events. Re-introducing species from 'external' sources invokes regional dynamics, and thus, different impediments to successful re-colonisation. After neutralising the specific agents that previously caused local extinction, relevant processes include population dynamics elsewhere in the species range, long-distance movements, and biogeographic distributions.

I also speculate that remnant and 'restored' (replanted or regenerated) vegetation may have different roles in wildlife recovery under different restoration scenarios. For example, revegetation may provide an environmental cue for prospecting individuals even though settlement occurs in remnant vegetation: that is, there is effectively a 'spatial lag' whereby the 'effect' of revegetation is evident not in the restored sites themselves but in remnant vegetation. New research exploring the concepts of 'within-landscape re-colonisation', 'external re-introductions' and spatial lags is commencing in partnership with the Glenelg-Hopkins CMA in south-west Victoria.