Revegetation and the Significance of Timelags in Provision of Habitat Resources for Birds

In many approaches to landscape visualisation and reconstruction for biodiversity management, vegetation is represented as being either present or absent. Revegetation is assumed to be possible, and new vegetation appears ‘immediately’ in a mature state, which is likely to drastically overestimate habitat suitability in the short-term. We constructed a simple temporal model of resource provision from revegetated agricultural land to estimate habitat suitability indices for woodland birds in south-eastern Australia. We used this model to illustrate the trajectory of change in biodiversity benefits of revegetation. As vegetation matures, its suitability for a given species changes, so a time-integrated assessment of habitat value is needed. Spatial allocation strategies, such as offsets, that may provide high value habitat in the long-term but imply shorter term population bottlenecks from a paucity of key resources (e.g. tree hollows) must be avoided. Given that vegetation may not meet both foraging and breeding requirements of a given species, populations may be limited continuously — by foraging constraints at some times, and by breeding constraints at other times. Animal species differ in their resource requirements so that optimisation involves compromises among species. Temporal processes associated with revegetation and differences in resource requirements of species complicate landscape reconstruction. Nevertheless, our analyses suggest that the time-course of vegetation development must be incorporated in models for optimising landscape reconstruction and for calculating revegetation offsets.