Mangrove restoration is guided by lifecycle responses to climatic forcing

Abstract Due to the range of ecosystem services provided, mangrove restoration is increasing worldwide. Mangrove restoration strategies have typically focused on either passive (i.e. re-establishing tidal regimes suitable for natural mangrove recruitment), or active (planting) restoration approaches. To date, mangrove restoration projects typically consider chronic environmental pressures at a site (e.g. the tide). However, acute or extreme weather events (e.g. waves, floods, droughts, etc) are important drivers of global mangrove loss and are rarely considered in restoration projects. In this study, the mangrove lifecycle ecosystem analysis and forecasting model was used to monitor the temporal and spatial effectiveness of passive and active mangrove restoration projects when exposed to routine tides and wind waves, and extreme weather events like floods, droughts and storm conditions. Passive restoration was the most recommended strategy for mangrove survival and ecosystem services across all tested environmental conditions, except constant wind waves. These outcomes were overcome by the active planting of mangrove saplings with stems tall enough to resist overturning and/or wave breaking forces. Planting was most beneficial when restricted to bed elevations where propagules would naturally recruit and when waves were present. Propagule availability was found to be critical in re-populating sites post climatic events (e.g. storms) and was most effective in ensuring the long-term development of active restoration strategies. Mangrove planting provided immediate returns on ecosystem services post-restoration, before converging with the outputs of passive restoration. This study provides previously missing guidance regarding mangrove restoration for a range of chronic conditions and extreme weather events, highlighting the importance of aligning restoration conditions with the mangrove lifecycle for tailored restoration strategies.