Mangrove rehabilitation: a review focusing on ecological and institutional issues

Abstract

Interest in mangrove rehabilitation has increased rapidly since 2003, as has awareness of the damaging effects of natural and anthropogenic pressures that contribute to mangrove loss, which is estimated at 1-2% per annum. The major pressures are from urbanization and other development in all areas and forestry and fisheries especially where communities depend on mangroves for their livelihood. However rehabilitation success has been uncertain, reflecting gaps in integration between human and ecological components of the rehabilitation system. In particular there are government level issues of gaps and inconsistency in policy and failure in application. Some rehabilitation efforts have had limited success for several reasons including: having insufficient information, using inappropriate methods, not involving local communities, or not following all the steps in the processes that have been identified in the literature. A multidisciplinary and integrated approach is needed to assist future planning and this needs capacity from a variety of areas in government, research and community. The review concludes with hope for a future where governments work with communities to develop policies and strategies for rehabilitating mangrove for resilience to changing environments.

Determining hydrological flow paths to enhance restoration in impaired mangrove wetlands

“…The topographic elevation recorded at sites 1 and 4 was 0.004 and 0.031 masl, respectively, which suggests that the soil collapsed between 0.10 and 0.16 m. The collapse of the soil, in turn, increased the level and duration of flooding to values similar to those of the fringe mangrove (on the edges of the Laguna de Términos), which explains why individuals of R. mangle colonized these sites after the hydrological rehabilitation. These results confirm the postulate that, while the restoration of the mangroves serves to rehabilitate the sites, recovery of the original biological community remains a challenge [40,62].…”

Ecoengineering with Ecohydrology: Successes and failures in estuarine restoration

“…Such attempts have also failed from a variety of other causes, including excessive periods of immersion drowning seedlings, colonising oysters growing on the stem and toppling the seedlings, floating marine debris and macroalgae toppling or defoliating the seedlings, waves uprooting the seedlings, substratum erosion by waves, and seedling burial by migrating mud waves. There is also soil acidification by excavating shrimp ponds in mangrove soils, and people and livestock directly destroying the newly created mangrove forest without the community involvement needed to protect the restored mangroves (Wolanski et al, 2009;Primavera et al, 2011;Dale et al, 2014;Samson and Rollon, 2014;Wolanski and Elliott 2015;Gensac et al, 2015). Much of this mangrove restoration has been conducted without documenting the methodologies and the real costs of the work, and without adequate site assessment and remediation measures (e.g., to restore or generate suitable tidal hydraulics).…”

Planning Development to Reduce Mosquito Hazard in Coastal Peri-Urban Areas: Case Studies in NSW, Australia

“…However loss of coastal wetlands is a major concern globally (Irving et al 2011 ) with urbanisation and development identifi ed as the most common cause of mangrove loss (Dale et al 2014 ). Losses in New South Wales (NSW) Australia have been estimated at 60 % for the period from European settlement (1788) to 1970 (Goodrick 1970 ) with losses continuing to occur (Pressey and Middleton 1982 ).…”

“…Key to rehabilitation success is a thorough understanding of the issues and options followed by restoration of the appropriate hydrologic conditions (Lewis 2005 ;Turner and Lewis 1996 ;Dale et al 2014 ). In practice, this can become complicated where unintended/unforeseen outcomes can occur.…”