Mangrove restoration in Costa Rica

No information

A pilot mangrove restoration project in Costa Rica demonstrating how mangrove planting can benefit habitat and species conservation, whilst boosting the local economy. About 40% of Costa Rica’s mangroves were deforested following the collapse of the country’s banana boom in the 1980s. A vigorous fern species has taken over much of the deforested area, preventing the mangroves from re-establishing. A pilot restoration project of 30 ha of mangrove in a protected wetland was implemented, involving clearance of the ubiquitous fern, planting of saplings, and continued fern removal for a few years to prevent it from out-competing the mangrove trees. This pilot successfully enabled the mangroves to re-establish, and was found to be economically viable – a community could receive up to $1500/ha restored, and could restore over 100 ha/year.

No information

This project has proven to be successful both in terms of conservation and livelihood benefits, so has great potential for up-scaling across the 2000+ ha of fern-dominated waters in the protected wetland. One barrier to overcome is developing a framework for funding restoration on public land, since previous successful payments for ecosystem services schemes in Costa Rica have been restricted to private land. A framework could be developed to fund the restoration through the blue-carbon market (water-based carbon credits). If done successfully, this could provide employment for at least three communities for two to three decades. 

Mangrove restoration also benefited a locally-important mollusc species – mud cockles known as piangua. These cockles have served as the main source of income for several Costa Rican communities for decades. However, due to over-harvesting and loss of mangrove habitat, the population and size of individual cockles has been plummeting. Mangrove restoration not only creates more habitat for this species but it also gives local people an alternative source of income, meaning cockle harvesting can be reduced. Together with controls on the number and size of cockles that can be harvested, this is expected to permit the recovery of the cockle population and allow people to benefit from this income source for years to come.

Both pianguas and mangroves became especially valuable to rural coastal communities following the collapse of Costa Rica’s banana boom in the 1980’s. In the decades that followed, Costa Rica lost more than 25,000 hectares of mangroves – about 40% of the country’s total – as the timber was a main income source for local communities. The piangua depends on the mangroves, especially red mangroves of the genus Rhizophora. The tree’s stilt roots in the muddy banks and its tolerance to salinity and high tides make for the perfect piangua home. But the mollusc population is not quickly replenished. 

The fern (Acrostichum aureum) has a pan-tropical distribution and can be found naturally within mangrove ecosystems throughout the tropics. Typically, the ferns’ dominance is kept in check by the mangroves and only small pockets exist between the trees and narrow channels. But when the mangroves were cleared 30 to 40 years ago, the sun-loving fern established aggressively and gave no chance for young mangrove trees to regrow.

Over 2,000 hectares of this huge, 20,000-hectare wetland is dominated by the fern — areas that were cleared for firewood, posts, and tannins. Our goal — if we can develop the right techniques — is to see the rich carbon stores of mangrove trees restored and brimming with life.

The project is starting small - so far 30 hectares have been restored as part of the pilot-project. But the goal is to deliver clear results to government agencies, and the private sector, outlining the most efficient ways to simultaneously restore mangroves and stimulate local economies. Success would mean a win for the environment, and a win for the communities.

They are developing a tool so that their techniques can be used to restore mangrove ecosystems throughout this wetland, the country’s wetlands, and if they get this right, throughout Central America.

Now more than ever, the piangueros need alternatives to unsustainable economic returns from bananas, logging, and – if an over-intensive harvest continues – a locally extinct bivalve.

The only other opportunities in the region for those not suited to eco-tourism (that itself is fragile as we have seen in the global tourism collapse related to Covid-19) is working in the pesticide-intense monocultures of pineapple or palm oil. Not only damaging to nature but also dangerous to the workers’ health.

So far,  the pilot mangrove restoration scheme benefits both nature and people. Instead of communities within the region degrading biodiversity, the protected area’s managers have community neighbours that are encouraged to improve the overall health of the ecosystem that they depend upon.

Investing in mangrove restoration makes sense from every angle. Communities can earn stable incomes that stimulate the economy. Mangrove restoration efforts are far more affordable than other marine coastal restoration projects, and their carbon sequestration potential is unparalleled throughout the tropics. Plus, the flood protection provided by  mangroves can more than pay for itself.

Osa Conservation

Association of Piangueros

The National University

Andrew Whitworth PhD is an Affiliate Researcher at the Institute of Biodiversity, Animal Health & Comparative Medicine, The University of Glasgow, Scotland, and Executive Director of Osa Conservation, Costa Rica and Washington D.C. Follow him on Twitter for updates via @andyrainforest.