State of knowledge on the effectiveness of management interventions to restore degraded eucalypt woodlands

To support the persistence of Australian eucalypt woodlands, conservation of remnant vegetation must be augmented with ecological restoration of degraded ecosystems. Certainty about the effectiveness of restoration interventions is urgently required to consistently transition degraded woodlands to reference states. The aim of this meta-analysis was to quantify the effectiveness of restoration interventions to improve plant and edaphic attributes in degraded temperate and semiarid woodlands of Australia. Our structured literature search retrieved 35 studies that were suitable for analysis, which enabled assessment of six types of restoration interventions and 11 ecosystem response metrics. Effectiveness was quantified using estimates of the probability and magnitude of responses generated from Bayesian multi-level models. We found consistent increases with varying average levels for carbon (via sugar) addition (43%) and burning (27%) on native plants, burning on cryptogams (91%), and woody debris addition on soil moisture (35%) and carbon (21%). Native plants had a low probability of benefitting from slashing (0.33) or herbicide application (0.09). Slashing had a high probability of increasing introduced plants (0.83). Planting almost always failed to achieve reference levels for native plant communities, introduced plants, or soil phosphorus. A very high level of uncertainty was evident for the outcomes of herbicide and sugar addition on introduced plants. Overall, we found a paucity of adequate studies, including insufficient quantitative information on combinations of interventions, and a lack of effectiveness in common interventions. Our results indicate an urgent need for experiments to be embedded in restoration programs to improve certainty in restoration effectiveness.