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Substrate modification for enhanced native forest restoration, Reefton



Restoration of postmining substrates to native forest is a standard requirement of resource consents for mine sites located within areas of native forest in New Zealand. Unweathered waste rock presents significant challenges for plant growth, and past research highlights the importance of replacing soil as part of restoration. However, replacing soil with its horizon structure intact or even obtaining sufficient soil for restoration can be a challenge in some situations. In this paper, we describe the results of two trials undertaken at the OceanaGold Ltd. open-cast gold mine in Reefton to explore the influence of substrate conditions on the growth of native forest seedlings. We show that beech (Nothofagus) seedlings grown on A-horizon soil grew significantly better than those grown on soil mixed with waste rock, and both grew significantly better than plants grown just on waste rock. In the second trial, we show that bark chips are not a good substitute for soil. These results confirm the importance of having the correct substrate for successful native forest restoration.