Capturing crabs and carbon in the fight against climate change in Viet Nam

by Jenty Kirsch-Wood, Senior Technical Advisor

April 24, 2019

Regenerating mangroves is muddy, complex work.  In Nam Dinh Province, twenty years ago coastal defence forests were healthy, but over the years, forests have thinned. To experience this first hand, I tied-on a pair of special cotton mangrove mud-socks and boarded a small local fisherman’s boat in Nam Dinh province and headed out into the mangrove forests.  I was part of the team working with local communities to replant and regenerate mangroves under the Government-UNDP-GCF coastal resilience project.

I was there because local foresters were not used to tracking how much carbon their mangrove forests can store as part of their daily work.  As carbon build up in the atmosphere causes global warming, the more carbon they store the more they help in the fight against climate change.

I’d been working with one of Viet Nam’s preeminent mangrove specialists, Dr. Phuong, to develop innovative ways for our new GCF funded project to track not only survival rate, but also carbon capture.  Its more complicated that it might sound, as carbon capture varies considerably based on factors like species, location and growth rate.  Working with Government experts, scientists and other stakeholders, Mr Phuong was quite confident that the carbon estimator tool he’d developed was scientifically sound and based on Viet Nam’s special mangrove conditions. He wanted to make sure the system was feasible and easy to use for our field teams. I tagged along and got a first-hand education into the local battle of goats, grass, crabs and ducks in the mangrove mud plains.

Ms Tuan, head of the locally owned mangrove planting company that had been working with the project outlined the dilemma.  Over the last twenty years, some trees fell prey to the increasingly cold nights in winter or died off in big storms.  New trees couldn’t grow back as quick growing grass species filled the gap, and goat farms moved in.  To make things worse, it turns out that new mangrove shoots are the favourite food of local crabs, so natural forests couldn’t regenerate.  Local communities weren’t happy with the loss, they knew the forest is a vital coastal defence against the impact of major typhoons, and they saw erosion increasing and that the natural balance of their fishing and aquaculture-based livelihoods was at risk.

So Ms Tuan had been working with local residents to fight back against the grass, goats and crabs and to help the local forest regenerate.  She introduced me to Mr Nguyen- until last year he’d been a fisherman and goat farmer in the mangrove canals.  Now she had trained him how to plant and maintain mangroves, and he had developed a separate side-line business in sustainable crab catching.

Ms Nguyet, Deputy Director of the UNDP local team explained how the project had been working with local foresters to develop local nurseries with diversified mangrove species more suitable to a world with more extreme temperatures and intense storms.  Trees were nurtured for the first year, so when they were planted they were hardier, and less tasty to crabs. Sites were fenced, and sustainable crab traps set at strategic locations to further protect the trees and provide carers with a bit of extra cash or a tasty dinner when they got home.  Local community members had agreed to move the goats, and earned income through tending mangroves, and keeping local bulrushes at bay (varieties in this part of Viet Nam can grow one meter per month).   UNDP was also supporting affected families with other livelihoods options.

“So far survival rates from last year are about 90%” Ms Nguyet told me “that’s far higher than some previous projects in the area where about 50% of trees could be expected to survive.”  She and the team were excited to show the progress they’d made.  After a hot morning marking GPS location, wading through high grass and deep mud to measure the old and new trees in the area, it was time to had back to the office to enter data and calculate baselines and progress.  By the end of 2019 Ms Nguyet estimates that her team will have regenerated or replanted over 800 hectares of coastal mangroves in Nam Dinh.  When she entered that estimate into the calculator tool which can consider species, ecosystems and other factors, so that it can be added to the project’s monitoring system.  But perhaps even more important, local communities would be able to count on strengthened mangrove buffer zones during the storm season and had charted a path to more sustainable, climate resilient future where they and the mangroves could thrive.