Abstract: Based on Google satellite map,the combined methods of transect walks and typical sample survey were used of make the germplasm resources investigation of the natural Cerbera Manghas population distributed in the coastal zone of 5 cities and counties of Haikou,Wenchang,Qionghai,Chengmai and Lingao in the Qiongbei region of Hainan Island.The results showed that small patches of Cerbera Manghas populatin were found only in Haikou and Wenchang out of 5 cities and counties,but the distribution areas were very limited.The fragmentation was serious,so the average distribution density of Cerbera Manghas(root diameter≥2.5cm)was just 95.59 trees/hm².Because of the interference and destruction of reclaimed farmlands and building artificial windbreaks,the limited population of Cerbera Manghas only remained in the edge of casuarina equisetifolia plantation,the edge of farm field and field bunds or in secondary forest.The age structure of Cerbera Manghas population in Haikou belongs to young aged forest,but the one in wenchang belongs to mature forest,the seed yield of Cerbera Manghas population in Wenchang was significantly greater than that in Haikou,with 58 seeds/tree and 6 seeds/tree,respectively.The natural regeneration ability of Cerbera Manghas was stronger,and the average densities of saplings and seedlings were 2 600 trees/hm².

Key words: Cerbera Manghas, investigation of germplasm resources, coastal zone, Hainan Island