Mangrove restoration gives hope to Indonesia’s sinking shores
Aquaculture, fisheries and coastal agriculture
Coastal wetland conservation
On World Wetlands Day, we look at how communities in Indonesia are turning to mangroves to buffer themselves against rising seas and more intense storms.
This feature story was originally published by UNEP
In a village on the Indonesian island of Java, eight men are wielding saws and machetes with practiced precision, preparing long bamboo poles that they will use to defend their embattled community.
The men are fighting back against the erosion and rising sea levels that have swallowed up vast areas of land along Java’s north coast, including in their home district of Demak. Key to their strategy is restoring a protective belt of mangroves.
“To do this, we create traps for sediment from local bamboo and nets,” explained Ahmad Busro, a community leader, as the poles piled up behind him. “The hope is that when enough sediment accumulates, seeds that naturally drop off the mangrove can settle and grow.”
This innovative approach to mangrove restoration is part of a multipronged effort pioneered by Wetlands International to harness the power of nature to benefit both people and nature.
In December, the UN Decade on Ecosystem Restoration selected the “Building With Nature” programme in Demak among its first 10 UN World Restoration Flagships to inspire the growing global movement to revive the natural world.
Inger Andersen, Executive Director of the United Nations Environment Programme (UNEP), described the programme as “a stellar example of smart and forward-looking adaptation work in action.
“It’s a model worth replicating for how countries can use nature to ward off the severe impacts of climate change while simultaneously creating new economic opportunities for people,” Andersen said as the flagships were announced.There is growing momentum behind the UN Decade’s mission to conserve and regenerate ecosystems on land and sea to address the triple planetary crisis of climate change, biodiversity loss and pollution. Humans have significantly altered three-quarters of the Earth’s dry land and impacted two-thirds of its oceans.
Fishing communities in Indonesia’s Demak regency have struggled in recent years amid rising sea levels. Photo Credit: UNEP/Nathanial Brown
In December 2022, nations agreed a new Global Biodiversity Framework that includes ambitious restoration targets. Under the framework, countries promised to restore at least 30 percent of degraded land and water areas.
Rising water, sinking land
Demak’s fisherfolk and shrimp farmers ply the coastline and waterways in boats painted in red, green and sky blue. But the cheerful vessels chug past grim reminders of the threat they face: abandoned fields and shrimp ponds, flooded homesteads, half-submerged tombstones.
The causes are multiple: global warming is driving up sea levels, raising the risk of flooding; waves and currents have strengthened, intensifying erosion; much of the protective belt of mangrove forest was cut to create more fish ponds; and the land is sinking because of excessive groundwater extraction.
“Demak’s coastlines have moved way back, so much so that a big chunk of its coastal land has gotten submerged,” said Muhammad Yusuf, Director of Coastal and Small Island Management at the Indonesian Ministry of Marine Affairs. “Hundreds of thousands of hectares of land are disappearing.”
Off Demak’s coast, global warming is driving up sea levels, waves and currents have strengthened, and a protective belt of mangrove forest has been cut back, leaving the area prone to flooding. Photo Credit: UNEP/Nathanial Brown
Past attempts to reinforce the coast have involved concrete sea walls and mangrove replanting schemes. But the heavy walls sank into the soft mud and the water was too deep and turbulent for the mangrove saplings.
This time, the community in Demak has found a more natural solution. Villagers and contractors have erected some 3.4 km of wave-calming structures in the shallows along a 20 km stretch of the coast. Instead of washing away precious soil, the tides deposit part of their sediment load, creating good conditions for mangroves to re-grow.
“When a mangrove forest is rehabilitated and is in good condition, the balance in the ecosystem provides a range of benefits to the community,” said Apri Susanto Astra, programme coordinator at Wetlands International Indonesia. “A good mangrove forest will act as a habitat for marine life, including fish and shrimp.”
Farmers have also agreed to let mangroves grow on part of their land after learning about how the trees not only protect against erosion but also improve conditions in their ponds. Nearly 300 farmers have been schooled in sustainable techniques such as the production and use of organic fertilizer that have boosted their returns – sometimes spectacularly.
Fishers have found that mangroves can be a haven for shrimp and that planting the trees can boost their catch. Photo Credit: UNEP/Nathanial Brown
Astra said this environmentally friendly approach eliminated the use of artificial fertilizer and improved the survival rates of both farmed fish and shrimp.
“I used to only harvest 10 kilos of shrimp, but now it is more than 50 kilos,” said Nur Hayati, a local fisher who attended the training. She said the extra income meant that she could afford to put her children through college.
Wetlands International, a partner of the UN Decade on Ecosystem Restoration, implemented the programme in Demak along with the Indonesian government, technical experts, partner organizations and local people, supported by Dutch funding. Since 2015, about 120 hectares of mangroves have been restored and more than 300 ha of aquaculture ponds are being managed with sustainable techniques. Some 70,000 people stand to benefit from increased resilience to climate change.
Another bonus of natural regeneration is the richness of the mangrove forest. While replanting schemes tend to use seedlings of only a few species, a dozen mangrove species have taken root around Demak, a diversity that makes the forest more resilient to climate change and other stressors.
Wetlands International says a key element of the flagship was how it brought engineers and other specialists together with non-government organizations and communities to tailor solutions to local conditions.
Pieter van Eijk, head of Wetlands International’s deltas and coasts programme, said the experience in Demak helped “create a formula that can be used in other locations.” In Indonesia, 13 districts have copied the approach and “we will now use these lessons to take Building with Nature projects to other parts of Asia,” van Eijk said.
About the UN Decade on Ecosystem Restoration
The United Nations General Assembly has declared the years 2021 through 2030 the UN Decade on Ecosystem Restoration. Led by the UN Environment Programme and the Food and Agriculture Organization of the UN, together with the support of partners, it is designed to prevent, halt, and reverse the loss and degradation of ecosystems worldwide. It aims at reviving billions of hectares, covering terrestrial as well as aquatic ecosystems. A global call to action, the UN Decade draws together political support, scientific research, and financial muscle to massively scale up restoration.
About Building with Nature in Indonesia
This World Restoration Flagship is coordinated by the Indonesian Ministry of Marine Affairs and Fisheries and the Indonesian Ministry of Public Work and Housing, Wetlands International and Ecoshape with support from Witteveen + Bos, Deltares, TU Delft, Wageningen University & Research, UNESCO-IHE, Blue Forests, Kota Kita, Von Lieberman, the Diponegoro University, and local communities. The initiative is financially supported by: The Dutch Sustainable Water Fund on behalf of the Dutch Ministry of Foreign Affairs, The German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) as part of the International Climate Initiative (IKI), the Dutch Postcode Lottery.