Assessing mangrove clearance methods to minimise adverse impacts and maximise the potential to achieve restoration objectives

Abstract

Management strategies in response to mangrove expansion in New Zealand include clearance, with the objective to restore the ecological and social values associated with sandflat habitats. However, it is unclear whether restoration of sandflats is achievable following mangrove clearance, or which methodologies minimise adverse impacts and maximise the potential to achieve restoration objectives. Four clearance sites were assessed for sediment characteristics and macrofaunal communities over 36 months following mangrove clearance to compare clearance methodology (hand or mechanically cleared), site characteristics (sheltered or exposed), size and shape. Hand clearances and sites exposed to greater hydrodynamic forces showed greatest transition to adjacent sandflat. However, our results suggest that transition to sandflat is unlikely within the first five years following mangrove clearance. This study fills gaps in science that are required to inform future mangrove clearance operations and monitoring, expectations of clearance outcomes and future management approaches.

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