Restoration Tonle Sap, Cambodia

tonle sap, Flooded forest in the mekong basin

Tonle Sap Lake, located in the lower Mekong River Basin, is one of the world's largest and most productive sources of freshwater fish and directly supports the livelihoods of more than one million people.

It is listed as a UNESCO Biosphere Reserve, contains three Ramsar sites and provides habitat for approximately 300 species of fish and numerous IUCN-listed threatened birds, mammals and reptiles.

During the Asian monsoon, the Tonle Sap River, fed by sediment-rich water from the Mekong, reverses flow and the lake level rises up to eight meters, flooding a vast floodplain area. This floodplain feeds fish that provide protein for millions of people in a country where 40 percent of children suffer from malnutrition. The extensive flooded forests and scrublands of Tonle Sap are one of the most important "irretrievable carbon" sites in the world, storing an immense amount of carbon due to the flooded environment, which slows decomposition.

However, Tonle Sap is rapidly being degraded by upstream hydropower development, climate change, illegal fishing, settlement expansion, agricultural expansion, exploitation of forests for timber and fuelwood, and uncontrolled forest fires.

The people of Tonle Sap are among the poorest and most marginalized people in Cambodia. Most are landless and live in floating villages, which offer few livelihood options beyond fishing.

The vast Tonle Sap floodplain is covered by flooded forest and scrub, grassland, invasive weeds, wetlands and rice fields. The most important is the flooded gallery forest, which since 2000 has decreased by about 10%.

The gallery forest is mainly found near the permanent water's edge, harbors the tallest trees and stores the most carbon. It also provides habitat for threatened species, such as the endangered hairy-nosed otter(Lutra sumatrana), and protects the villagers' houseboats from wind and storm-driven waves.

Tonle Sap's dense flooded thickets provide complex habitat for fish when flooded, but store less carbon than gallery forest. Dry season forest fires, particularly in the warm El Niño years of 2015 and 2016, destroyed large areas of flooded forest and scrub.

These burned areas are colonized by dense thorny thickets of the invasive weed Mimosa pigra which provides hostile habitat for Tonle Sap fish. Other areas have been cleared for rice cultivation.

Source: Conservation International

While recent years have seen an increase in the illegal clearing of land from Fishing Communities for rice fields, the Government of Cambodia has strengthened its position of protecting flooded forests. Large areas of illegally deforested land have been reclaimed under the control of the State, which has decreed the restoration of deforested and degraded flooded forests and thickets since 2010.

Fishing communities are particularly interested in restoring recently deforested and returned lands, demonstrating their commitment to community management.

Source: Conservation International

The project will be coordinated by Conservation International and will be implemented through a joint work with the Fishing Communities that will apply different restoration techniques: assisted natural regeneration, replanting using nursery-grown seedlings and direct seeding. We will also work with the partner communities in areas of community education, surveillance and forest fire control to ensure that the site is protected and that regeneration continues.

The final objective of the project is to restore 500 hectares of flooded forests, which will allow the capture of some 46,000 tCO2eq over a 30-year period and will generate multiple additional environmental and socioeconomic benefits.

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We have a great opportunity to improve ecosystems and benefit future generations.

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