Assessing rehabilitation success 30 years on. The case of hydroelectric developments in Tasmania, Australia

Construction of two hydroelectric power developments between 1974 and 1983 in Tasmania, Australia were the first in the state to use active and progressive rehabilitation during construction. The rehabilitation treatments included stockpiling of peat stripped from construction areas and future inundation areas. Following the completion of construction work at a site, peat was re-spread and the area fertilised and seeded with local provenance native species whom anecdotal evidence showed to be colonising species in adjacent undisturbed plant communities. Today, many of these rehabilitated sites are difficult to visually distinguish from the surrounding vegetation; a factor that has been taken as a measure of rehabilitation success. However, the success of the rehabilitation works had not been quantitatively assessed. This study assessed the success, or otherwise of the rehabilitation and compared sites which received the peat spreading treatment to those that did not. The rehabilitated sites assessed showed good recovery in terms of species richness, biomass accumulation and erosion protection after 30 years. Species richness was higher on the disturbed sites when compared with the undisturbed scrub sites. The disturbed and rehabilitated sites showed a wide range of ground cover floristics that also varied according to whether they had received peat treatment. Sites that had been treated with peat had a wider range of species across sites and higher mean species richness at sites compared with those left untreated. All rehabilitated sites, either peat treated or not, showed good erosion protection from vegetation cover, bryophytes, lichen and concomitant low bare ground.