Abstract
Floristically rich and ecologically complex, Mediterranean-type ecosystems are rapidly being cleared for urban, horticultural and industrial development. A prime example is Banksia woodland, an ecosystem restricted to the Swan Coastal Plain in Western Australia. In order to compensate for the clearing of Banksia woodland due to urbanization, land developers are required to attempt biodiversity offsets whereby topsoil from newly cleared landscapes can be moved to degraded land with the aim of restoring Banksia woodland. Yet the science and practice of restoration ecology is not sufficiently advanced to know for certain that this aim can be achieved. Assessing the efficacy of a spectrum of restoration techniques will provide new insights for the restoration of endangered plant communities, and critically, a test of the feasibility of biodiversity off setting.
The topsoil was subjected to three site-scale treatments: altering topsoil depth, ripping & herbivore exclosures. Additionally, six plot-scale treatments were applied to explore germination effect (three smoke water-related, topsoil heating) and competition effect (herbicide & artificial shade installation) on native seedlings’ emergence and survival.
Significantly fewer seedlings emerged from ripped (17.01 ±1.03 SE) than unripped plots (37.99 ±2.05 SE). Species richness was similar across all treatments with a total number of native plant species emerging from the transferred topsoil of 129 in the first year and 115 in the second year. Mean survival rates of native perennial seedlings were very low (year I = 11.1% & year II = 1.2%). The maximum average survival was recorded under artificial shade (41% ±12.2 SE).