Summary

The aim of this paper was to describe the genetic structure of populations of Austrodanthonia (Wallaby grass) and their relationship with their environment. This will not only have implications for revegetation success and seed sourcing issues but also for the management of native plant communities.

Up to four species were found to co-occur. As most populations consisted of at least four Austrodanthonia species, wildland seed harvesting will most likely contain a composite of species. Variation in flowering and growth characteristics for all species occurred amongst populations and were related to environment suggesting local adaptation. No differences between populations for water-use efficiency were found. Flowering was more protracted in spring compared to autumn which had a high degree of flowering synchrony. More flowers were produced in autumn, a season that may provide less risky conditions for seedling establishment. All species showed considerable overlap in flowering time and may provide a possible mechanism to facilitate hybridisation between species. This suggests that the reintroduction of southern populations into northern locations may result in less fit individuals and vice versa. Reproductive effort may not, however, be compromised with translocation as flowering may occur at any time for most species. Across the collection area, A. caespitosa was associated with higher rainfall localities. However, within these localities individual plants tended to occupy the least shaded, more exposed or drier sites.

This research clearly demonstrates that different traits can be expressed at different geographic scales so suggesting that local seed sources as the best site adapted material is problematic because local may not be easily defined. The formulation of broad recommendations for souring seed is therefore difficult. Decision making tools that balance the benefits of different seed sources against ecological risks and economic costs may provide general guidance.