In 2007 Wetlands International, in partnership with Mangrove Action Project(MAP), applied for and received support from Asia-Pacific Forum for Environment and Development (APFED) to produce a demonstration site that showcased Ecological Mangrove Restoration techniques, in the Krabi River Estuary Ramsar site, southwest Thailand. Due to issues concerning site control there was a delay to the start of the work and a move from the intended village of Ban Talin Chan to the adjacent village of Ban Lang Da, both about 30km from Krabi town.
The site chosen was a typical former aquaculture pond, abandoned for seven years before the project started and due to erosion of the mud walls, tidally flushed for three years. Despite this flushing and plenty of mangrove propagules available, the pond was not naturally regenerating. Having surveyed the site with a builder’s level, it appeared that the pond substrate was too low for mangrove growth – effectively mudflat. Thus the team planned and executed a programme to improve the topography and hydrology of the site to facilitate nature to regenerate itself.
This pond restoration project was initiated as mangrove clearance for aquaculture and subsequent pond abandonment is a very common problem around southeast Asia. To form a pond mangroves are normally felled and burnt before the mud is bulldozed to the sides to form the pond walls. The effect of this regarding and soil compaction is to lower the level of the substrate to a point that when under tidal influence again, the mud is too low and therefore saturated (anoxic) for mangrove growth. This is often accompanied by issues related to acid sulphate soils. Ponds have frequently been run at intensive and unsustainable levels of shrimp stocking, producing huge profits for a few years before succumbing to production problems including disease outbreaks, rising debts, requirements of expensive inputs and production of social issues and pollution.
This opportunity allowed the WI-MAP team to test and refine low cost methods to implement mangrove restoration in the way prescribed by the scientific community, including writers like Field and Lewis. Their guidance proposes improving the hydrology and topography to mimic natural mangrove as far as possible. But how is this actually done, without the aid of mechanical equipment (as this is technically illegal in Thailand and expensive)?
Thus slowly over time, channels were hand-dug, hills produced with the spoil, and mangrove seedlings inserted into the mud of random hills. Mangrove propagules were also dibbled into the unaltered substrate as a comparison. Further, seven control plots were marked out at various heights to monitor unaltered pond substrate.
Sadly the project was less participative that was planned due to certain WI management issues. However the project met with the village each time they worked at the site, keeping villagers abreast of developments and they and the local children were frequent visitors to the pond. Further, expectations were very carefully controlled at the outset to avoid disappointment.
Thailand Environment Institute (TEI) was employed by APFED to oversee the project. During their final visit, with the APFED donors, WI and MAP staff talked the visitors through the species that were now happily growing onsite, successes and things that had worked less well, the huge amount that had been learnt by the project team, and how other people and visitors had already benefited from the project including a sister-project in Ban Talay Nok, Phang Nga province.
Note : Further details can be found in an in-depth final report or PowerPoint presentation.