Effects of local environmental heterogeneity and provenance selection on two direct seeded eucalypt forest species

Abstract

Large‐scale land‐clearing has threatened Australian forest biodiversity, particularly within the South East Queensland bioregion where nearly 55% of humid‐climate eucalypt forest has been cleared. Restoration is key to the persistence of these forests but conventional reforestation techniques, including the exclusive use of locally sourced seed and nursery‐raised planting stock, are being reconsidered in terms of cost‐effectiveness and ability to create climatically resilient forests. In this study, we examined the success of a 2‐year‐old direct seeding restoration project of Corymbia citriodora and Eucalyptus tereticornis from one local and two nonlocal provenances. We established a field trial to compare germination rates of E. tereticornis seed and seed‐balls from the varying provenance sources in the field and in controlled laboratory growth chambers. We found no evidence of local provenance superiority in the field or in laboratory conditions. Periods of unseasonable rainfall and flooding may have constrained E. tereticornis germination in the field site. We conclude that direct seeding with seed‐balls may represent an effective method for establishing C. citriodora in South East Queensland, and that the approach warrants further investigation with other restoration species. Matching species with site conditions should be an initial consideration before long‐term revegetation investments are made.