(AP) - KUALA LUMPUR, Malaysia-Mangroves that bore the brunt of last year's tsunami in Indonesia and other places have been replaced with hurriedly and improperly planted trees that may wither soon and leave coastal communities vulnerable, experts warned Tuesday.

Saplings were planted in areas where their survival is precarious because species have been wrongly matched to the soil and their positions were prone to erosion, environmentalists told a U.N.-backed meeting on managing coastal ecosystems to mitigate tsunamis.

"There are some false starts, since people have been rushing as a response to the tsunami," said Faizal Parish, director of the Malaysian-based Global Environment Center. "Long-term efforts to maintain these forests will be hindered if the mangroves have a low survival rate."

The improper replanting has occurred mainly in Indonesia's hardest-hit Aceh province on Sumatra island, but observations show similar problems in other nations like India and Sri Lanka, where mangrove swamps were battered by last December's tsunami, Parish said.

Ecologists have said anecdotal evidence and satellite photography showed mangrove forests and other wetland vegetation functioned as a natural barrier against the tsunami, helping to curtail the loss of lives and property in coastal villages.

Some 25,000 hectares (61,800 acres) of mangroves in Sumatra were devastated by the waves. Forests elsewhere have long been threatened by commercial exploitation, which has reduced mangroves in tsunami-affected countries by more than 25 percent since the 1980s.

Governments in Indonesia, India, Malaysia, Sri Lanka and Thailand will need to spend a total of more than US$30 million (€24.5 million) to plant mangroves and other beach vegetation such as casuarina trees on 1,300 kilometers (800 miles) of their coastlines, Parish said.

Other delegates at the one-day conference, co-organized by the U.N. Development Program, the International Society of Mangrove Ecosystems and other groups, urged international donors to help some of the developing countries foot the bill for the rehabilitation.

"It would be impossible for Indonesia to cope alone with the cost and damage, though we have now started replanting for the next few years," said Aprilani Soegiarto, the Indonesian-based chairman of Plant Resources of Southeast Asia.

Researchers said planting mangroves is nevertheless cheaper than building seawalls, and such forests serve other ecological functions such as helping to preserve biological diversity.