Hundreds of hectares of melaleuca forest in U Minh Ha National Park face severe decline, with many trees dead and fallen across vast areas. Master Nguyen Huu Thien, an independent expert on Mekong Delta ecology, states the primary cause is the altered natural flood-dry regime of the ecosystem.

Following a major fire in 2002 that damaged approximately 4,300 hectares of melaleuca forest, management shifted to prioritizing water retention to mitigate fire risk. A grid-canal system was subsequently built for fire prevention and control. While enhancing response capabilities during forest fires, this system also altered the natural water dynamics within the peat layer.

Master Nguyen Huu Thien, an independent expert on Mekong Delta ecology. Photo: Hoang Nam

The canal networks increase water loss due to evaporation and disrupt underground flow. In the dry season, canals draw water from the peat, causing the peat layer to dry out faster and increasing fire risk. To counter this, water levels are maintained at a high level. However, uneven terrain results in prolonged flooding in many low-lying areas, leading to widespread melaleuca tree deaths.

According to Thien, the U Minh melaleuca forest naturally adapts to a cycle of approximately six months of flooding and six months of dryness each year. Melaleuca trees can survive flooded conditions but require dry periods for root recovery and nutrient absorption.

Hundreds of hectares of U Minh Ha melaleuca forest are in decline. Video: Chuc Ly

"When flooded year-round, tree roots lack oxygen, weaken, and gradually die," he stated, noting these signs were warned about many years ago. Statistics from 2007 show about 35% of the melaleuca forest area died due to prolonged waterlogging.

Furthermore, prolonged flooding degrades the peat layer, which is the foundation of the U Minh ecosystem. When tree roots die, peat water accumulates, affecting photosynthesis. The peat layer gradually loses cohesion, causing many trees to uproot and fall during the dry season.

If this situation continues, many areas of melaleuca forest could be replaced by flood-tolerant species such as ferns, reeds, and sedges.

To preserve the melaleuca forest, Thien suggests that a fundamental solution is to restore the seasonal flood-dry regime, closer to the natural conditions of the U Minh ecosystem. During the dry season, groundwater levels should not fall below 50 cm beneath the peat surface to maintain moisture and limit fire risk. At the end of the rainy season, the forest needs adequate water reserves to compensate for losses during the dry season.

Trees uprooted and fallen everywhere. Photo: Chuc Ly

Additionally, due to the uneven peat terrain, water management requires implementation in separate compartments rather than applying a single water level across the entire national park. The national park should study blocking both ends of the canals to reduce water loss, limit peat oxidation, and establish an appropriate water monitoring and regulation system.

Doctor Duong Van Ni, an expert on wetland ecology and water resource management in the Mekong Delta, shares this view, asserting that prolonged water retention, especially in stagnant areas without flow, is the main reason for widespread melaleuca tree deaths.

After the melaleuca forest declines, many clearings form and are gradually replaced by plants such as grass, sedges, reeds, and ferns. Photo: Chuc Ly

According to Ni, in areas where melaleuca trees have died extensively, the ecosystem may gradually transform into a swamp with the emergence of aquatic plants, followed by ferns and reeds. At that point, the area ceases to be a melaleuca forest. Re-establishing a woody plant community could take 50 to 70 years.

Experts emphasize that the situation in U Minh Ha illustrates that forest and wetland conservation must be based on the ecosystem's natural cycles, rather than solely focusing on fire prevention.

Chuc Ly