The earthquake and tsunami that devastated coastal area in Nanggroe Aceh Darussalam Province and North Sumatra Province,especially Nias Island on December 26,2004,caused damage to most mangrove and coastal forests in the areas.Before the 2004 tsunami,there is no report or publication about mangrove and coastal vegetation in Nias Island.The aims of this research were to describe the mangrove forests and coastal vegetation after tsunami disaster and to learn the ecological functions of mangrove forests and coastal vegetation on shore protection.Field surveys,in eastern,northern and western coast of Nias Island within 10 days of the middle weeks in March 2005 and in southern coast of Nias Island within 6 days of the first 2 weeks in November 2006 after the 2004 tsunami,were conducted.Our research results showed that dense mangrove forests and coastal vegetation had been proven to be effective on protecting coastal area from the tsunami,while heavy damage occurred in the areas that have degraded mangrove and coastal forests.Therefore,mangrove forests play an important role on shore protection,and this protection depends on the quality of the mangrove habitats.It should be noted that degraded habitats or habitats with mangrove associate species instead of true mangrove species do not provide adequate protection. The earthquake and tsunami that devastated coastal area in Nanggroe Aceh Darussalam Province and North Sumatra Province, especially Nias Island on December 26, 2004, caused damage to most mangrove and coastal forests in the areas. Before the 2004 tsunami, there is no report or publication about mangrove and coastal vegetation in Nias Island. The aims of this research were to describe the mangrove forests and coastal vegetation after tsunami disaster and to learn the ecological functions of mangrove forests and coastal vegetation on shore protection .Field surveys, in the eastern, northern and western coast of Nias Island within 10 days of the middle weeks in March 2005 and in southern coast of Nias Island within 6 days of the first 2 weeks in November 2006 after the 2004 tsunami, were conducted. Our research results showed that dense mangrove forests and coastal vegetation had been proven to be effective on protecting coastal area from the tsunami, while heavy damage occurred in the areas that have de graded mangrove and coastal forests.Therefore, mangrove forests play an important role on shore protection, and this protection depends on the quality of the mangrove habitats. It should be noted that degraded habitats or habitats with mangrove associate species instead of true mangrove species do not provide adequate protection.