Le Thanh Dung, deputy director of U Minh Ha National Park, said the extent of the damage had yet to be fully assessed, but significant forest degradation had already been recorded.
Field observations indicate that deterioration is most evident in low-lying areas that remain flooded for more than six months each year.
Dung said the decline was partly linked to the ageing of long-established melaleuca stands, which have become increasingly vulnerable to dieback and collapse.
He also attributed the problem to the release of reddish-coloured water from underlying peat soils. The water reduces light penetration, hindering photosynthesis and preventing natural regeneration of young melaleuca trees.
Over time, peat layers ranging from 0.5 to 1.5 metres thick have formed beneath the forest. During the dry season, the peat becomes loose and unstable, making it difficult for mature trees to remain upright.
As the native melaleuca ecosystem gradually deteriorates, it is being replaced by natural grasslands and wetland vegetation, including sedges, reeds and ferns.
The degraded area is estimated at between 200 and 300 hectares, mainly in subzones 1 and 4. If melaleuca trees fail to regenerate, the affected areas could eventually shift to other ecosystem types.
Park authorities plan to seek solutions to better regulate water levels in an effort to restore forest growth. The park is also working with national research institutions to assess the condition of both the peatland and forest ecosystems.
U Minh Ha National Park is one of three major wetland conservation sites in the Mekong Delta and forms part of the core zone of the UNESCO-recognised Ca Mau Cape Biosphere Reserve.
The park covers more than 8,500 hectares and is home to peatland melaleuca forests and a rich diversity of flora and fauna, including rare and threatened species.
