Early impacts of harvesting and burning disturbances on vegetation communities in the Warra silvicultural systems trial, Tasmania, Australia
Neyland, M and Jarman, J, Early impacts of harvesting and burning disturbances on vegetation communities in the Warra silvicultural systems trial, Tasmania, Australia, Australian Journal of Botany, 59, (8) pp. 701-712. ISSN 0067-1924 (2011) [Refereed Article]
Impacts on the understorey vegetation of a range of silvicultural alternatives to clearfelling in lowland Eucalyptus obliqua wet forest were studied over a decade in the Warra silvicultural systems trial in southern Tasmania. The treatments were clearfell with understorey islands, patchfell, stripfell, dispersed retention, aggregated retention, and single-tree/small-group selection. High intensity burning, low intensity burning and no burning were variously applied as part of these treatments. Three understorey types were studied, including one wet sclerophyll community and two rainforest communities. Wherever burning occurred across the research trial, the regenerating vegetation was floristically wet sclerophyll with an incipient composition consistent with that of the pre-harvest wet sclerophyll community. Sites previously occupied by rainforest understoreys retained occasional rainforest elements, but the regeneration was overwhelmingly sclerophyll in nature. There were no consistent differences in the floristic composition of the regenerating vegetation, after burning or harvesting disturbance, that could be attributed to the silvicultural system. However, field observations and the results of a related, subsequent study suggest that, in designing silvicultural trials similar to the present one, close attention should be paid to the size of quadrats in relation to the level at which disturbance impacts are operating. The response of the vegetation at edges created by the treatments, and in the undisturbed forest beyond, supports the finding that edge effects on the vascular flora extend for less than 10 m into the undisturbed forest.